Technical Report

NREL/TP-560-49129

September 2010

Learning Demonstration Interim 

Progress Report – July 2010 

K. Wipke, S. Sprik, J. Kurtz, and T. Ramsden
National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393

303-275-3000 • www.nrel.gov

NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency and Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

Contract No. DE-AC36-08-GO28308

Technical Report

NREL/ TP-560-49129

September 2010

Learning Demonstration Interim 

Progress Report – July 2010 

K. Wipke, S. Sprik, J. Kurtz, and T. Ramsden

Prepared under Task No. H270.8100
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i

Executive Summary

This report documents and discusses key results based on data through December 2009 from the 

U.S. Department of Energy’s (DOE) Controlled Hydrogen Fleet and Infrastructure Validation 

and Demonstration Project, also referred to as the National Fuel Cell Electric Vehicle (FCEV) 

Learning Demonstration. This report serves as one of many mechanisms to help transfer 

knowledge and lessons learned within various parts of DOE’s Fuel Cell Technologies program, 

as well as externally to other stakeholders. It is the fourth such report in a series, with previous 

reports being published in July 2007 [1], November 2007 [2], and April 2008 [3].

This report also marks a transition with the makeup of the industry participants who initiated the 

project in 2004. The projects started with four automotive OEM & energy partner teams. Since 

that time, DOE’s California Hydrogen Infrastructure Project began providing data, and 

additional hydrogen fueling infrastructure is being installed in California under state and local 

funding that will also soon be providing data to DOE’s National Renewable Energy Laboratory 

(NREL). We have also seen the completion of the project for two of the four original OEM and 

energy partner teams, who provided their last data by early 2010. New analytical results 

generated after this report will need to be approached differently, given the fact that there are 

only two automotive companies now providing data, and their sensitive data still needs to be

protected from competitors. Therefore, while this report is not a final report from the project, it 

is potentially the last comprehensive report to provide new commentary on the data involving all 

four original automotive OEM teams up to December 2009.

NREL has now analyzed data from almost five years of the seven-year project. During this time, 

144 vehicles were deployed, 23 project refueling stations were placed in use, and no fundamental 

safety barriers were identified. We have analyzed data from over 436,000 individual vehicle 

trips covering 2,500,000 miles traveled and over 130,000 kg hydrogen produced or dispensed. 

Key objectives of the project are to evaluate fuel cell durability, vehicle driving range, and onsite hydrogen production cost. Progress towards these objectives will be briefly highlighted. 

Fuel Cell Stack Durability: Many improvements have been made in NREL’s fuel cell 

durability analysis methodology, including using a two-segment linear fit and using a weighting 

algorithm to come up with a more robust and automatic fleet average. Now that the data 

submissions are complete on first-generation stacks (no new first-generation stack data is being 

received), we can make some final conclusions about that generation of technology. The 

maximum number of hours a first-generation stack accumulated without repair is 2,375, which is 

the longest stack durability from a light-duty vehicle FCEV in normal use published to date that 

we are aware of. On average, the slope of the initial power degradation is steeper in the first 200 

hours and becomes more gradual after that. We also found that around 1,000 hours of data were 

required to reliably determine the slope of the more gradual secondary degradation. Finally, with 

significant drops in power observed at 1,900–2,000 hours, it appears as though this is a solid 

upper bound on first-generation stack durability (characterizing 2003–2005 technology). For 

second-generation fuel cell stacks (2005–2007 technology), the range of maximum hours 

accumulated from the four teams is now approximately 800 to over 1,200 hours, with the range 

of team average hours accumulated of approximately 300 to 1,100 hours. Relative to projected 

durability, the Spring 2010 results indicate that the highest average projected team time to 10% 
ii

voltage degradation for second-generation systems was 2,521 hours, with a multi-team average 

projection of 1,062 hours. Therefore, the 2,000-hour target for durability has been validated. 

Vehicle Driving Range: In FY 2008, the driving range of the project’s FCEVs was evaluated 

based on fuel economy from dynamometer testing (EPA adjusted) and on-board hydrogen 

storage amounts and compared to the 250-mile target. The resulting second-generation vehicle 

driving range was between 196 – 254 miles from the four teams, and met the 250-mile range 

objective. In June 2009, an on-road driving range evaluation was performed in collaboration 

with Toyota and Savannah River National Laboratory. The results indicated a 431-mile on-road 

range was possible in southern California using Toyota’s FCHV-adv fuel cell vehicle [4]

. More 

recently, the significant on-road data that have been obtained from second- and first-generation 

vehicles allowed a comparison of the real-world driving ranges of all the vehicles in the project. 

The data show that there has been a 45% improvement in the median real-world driving range of 

second-generation vehicles (81 miles) as compared to first-generation (56 miles), based on actual 

distances driven between over 25,000 refueling events. Obviously the vehicles are capable of 

two to three times greater range than this, but the median distance travelled between refuelings is 

one way to measure the improvement in the vehicles’ capability and the way in which they are 

actually being driven.

On-Site Hydrogen Production Cost: Cost estimates from the Learning Demonstration energy 

company partners were used as input to an H2A analysis to project the hydrogen cost for 1,500 

kg/day early market fueling stations (H2A is DOE’s suite of hydrogen analysis tools, with the 

H2A Production model focused on calculating the costs of producing hydrogen). Results 

indicate that on-site natural gas reformation could lead to a range of $8-$10/kg and on-site 

electrolysis could lead to $10-$13/kg hydrogen cost. While these results do not achieve the 

$3/gge cost target, two external independent review panels commissioned by DOE concluded 

that distributed natural gas reformation could lead to $2.75-$3.50/kg [5] and distributed 

electrolysis could lead to $4.90-$5.70 [6]

. Therefore, this objective was met outside of the 

Learning Demonstration project.

We have summarized the previously discussed key performance numbers, along with other 

metrics of interest such as fuel economy and fuel cell efficiency, and compared them to DOE 

targets in Table 1. The table shows that this project has exceeded the expectations established in 

2003 by DOE, with all of the key targets being achieved except for on-site hydrogen production 

cost, which would have been difficult to demonstrate through this project. 

Additional data accumulated and analyzed in 2010 – 2012 will assess the latest generations of 

FCEV technology, which include improvements over the second-generation systems included in 

the results to date. Future assessments will also include data analysis from many new hydrogen 

stations being commissioned in California, all of which will have 700-bar fueling capability. All 

80 composite data products (CDPs) published to date are included in this report as well as 

directly accessible from our Hydrogen Technology Validation Web site.
iii

Table 1: Learning Demonstration key performance metrics summary

Vehicle Performance Metrics Gen 1 Vehicle Gen 2 Vehicle 2009 Target

Fuel Cell Stack Durability 2,000 hours

Max Team Projected Hours to 

10% Voltage Degradation 1,807 hours 2,521 hours

Average Fuel Cell Durability Projection 821 hours 1,062 hours

Max Hours of Operation 

by a Single FC Stack to Date 2,375 hours 1,261 hours

Driving Range 103-190 miles 196-254miles 250 miles

Fuel Economy (Window Sticker) 42 – 57 mi/kg 43 – 58 mi/kg no target

Fuel Cell Efficiency at 1⁄4 Power 51 - 58% 53 - 59% 60%

Fuel Cell Efficiency at Full Power 30 - 54% 42 - 53% 50%

Infrastructure Performance Metrics 2009 Target

H2 Cost at Station (early market)*

On-site natural gas 

reformation

$7.70 - $10.30

On-site 

Electrolysis 

$10.00 - $12.90

$3/gge

Average H2 Fueling Rate 0.77 kg/min 1.0 kg/min

*Outside of this project, DOE independent panels concluded at 500 replicate stations/year:

Distributed natural gas reformation at 1500 kg/day: $2.75-$3.50/kg (2006)

Distributed electrolysis at 1500kg/day: $4.90-$5.70 (2009)
iv

Contents

Executive Summary .......................................................................................................................i

1 Project Background and Current Status.......................................................................1

1.1 Introduction.......................................................................................................................1

1.2 Approach...........................................................................................................................3

1.3 Status.................................................................................................................................5

1.4 Key NREL Analysis Accomplishments in FY 2010 ........................................................8

2 Results.............................................................................................................................10

2.1 Vehicle Results...............................................................................................................11

2.2 Infrastructure Results......................................................................................................22

2.3 Conclusions and Future Directions.................................................................................27

2.4 Recent Publications/Presentations..................................................................................28

2.5 References.......................................................................................................................29

2.6 Composite Data Products Referenced in Previous Discussion.......................................30

Figures

Figure 1: Photographs of the industry partners providing data to NREL on hydrogen fuel cell 

electric vehicles and fueling infrastructure included in this report (Photo credit: Keith 

Wipke)..............................................................................................................................2

Figure 2: Four examples of hydrogen production and refueling facilities (Photo credit: Keith 

Wipke)..............................................................................................................................3

Figure 3: Data flow for Hydrogen Secure Data Center (HSDC) analysis and results, overlaid on 

top of quantity of data received at HSDC ........................................................................4

Figure 4: Introductory screen of NREL’s Fleet Analysis Toolkit...................................................5

Figure 5: Cumulative number of vehicles deployed, by hydrogen storage type and status............6

Figure 6: Cumulative stations commissioned with current status...................................................7

Figure 7: Type and number of hydrogen stations with current status.............................................7

Figure 8: Current location of hydrogen stations in the United States as of August 2010. ..............8

Figure 9: Thumbnail images of the 80 CDPs published in spring 2010 .........................................9

Figure 10: Screen capture from NREL's composite data product Web site..................................10

Figure 11: Approach for characterizing voltage transient cycles..................................................18

Figure 12: Fuel cell system efficiency (CDP08)...........................................................................30

Figure 13: Fuel cell system operating power (CDP46).................................................................30

Figure 14: Fuel cell system energy within power levels (CDP53)................................................31

Figure 15: Trip length (CDP47)....................................................................................................31

Figure 16: Fuel cell electric vehicle with comparison to standard drive cycles (CDP66) ............32

Figure 17: Percent idle in trip with comparison to standard drive cycles (CDP65)......................32

Figure 18: Fuel cell system energy in trips (CDP55)....................................................................33

Figure 19: Daily driving distance (CDP56) ..................................................................................33

Figure 20: Time between trips (CDP54).......................................................................................34

Figure 21: Fuel economy (CDP06) ...............................................................................................34

Figure 22: Vehicle driving range (CDP02)...................................................................................35

Figure 23: Miles between refuelings (CDP80)..............................................................................35

Figure 24: Percentage of theoretical range traveled between refuelings (CDP33).......................36

Figure 25: Effective vehicle driving range (CDP34) ....................................................................36

Figure 26: Storage weight % hydrogen (CDP10) .........................................................................37
v

Figure 27: Volumetric capacity of hydrogen storage (CDP11) ....................................................37

Figure 28: Hydrogen storage system mass and volume breakdown (CDP57)..............................38

Figure 29: Vehicle hydrogen tank cycle life (CDP12)..................................................................38

Figure 30: Fuel cell system specific power (CDP59)....................................................................39

Figure 31: Fuel cell system power density (CDP58) ....................................................................39

Figure 32: Fuel cell system specific power, including hydrogen storage (CDP04)......................40

Figure 33: Fuel cell system power density, including hydrogen storage (CDP03).......................40

Figure 34: Hours accumulated and projected hours to 10% stack voltage degradation (CDP01) 41

Figure 35: Maximum fuel cell power degradation—Gen 1 (CDP69)...........................................41

Figure 36: Maximum fuel cell power degradation—Gen 2 (CDP70)...........................................42

Figure 37: Fuel cell stack projected hours as a function of voltage drop (CDP73) ......................42

Figure 38: Power drop during fuel cell stack operating period (CDP68) .....................................43

Figure 39: Projected hours to OEM low power operation limit (CDP71) ....................................43

Figure 40: Fuel cell stack operation hours (CDP67).....................................................................44

Figure 41: Fuel cell stack trips per hour histogram (CDP16) .......................................................44

Figure 42: Statistics of trips/hour vs. operating hour (CDP17).....................................................45

Figure 43: Primary factors affecting learning demonstration fleet fuel cell degradation (CDP48)

........................................................................................................................................45

Figure 44: Primary factors affecting learning demonstration team fuel cell degradation (CDP49)

........................................................................................................................................46

Figure 45: Fuel cell voltage (CDP07) ...........................................................................................46

Figure 46: Fuel cell transient voltage and time change (CDP75) .................................................47

Figure 47: Fuel cell transient cycles by mile and by minute (CDP74) .........................................47

Figure 48: Fuel cell transient rate by cycle category (CDP76).....................................................48

Figure 49: Fuel cell transient voltage changes by cycle category (CDP77) .................................48

Figure 50: Percentage of trip time at steady state (CDP79)..........................................................49

Figure 51: Fuel cell transient cycles outside of specified voltage levels (CDP78).......................49

Figure 52: Fuel cell electric vehicle maintenance by system (CDP64) ........................................50

Figure 53: Driving start time – day (CDP44)................................................................................50

Figure 54: Driving start time – night (CDP51) .............................................................................51

Figure 55: Driving by day of week (CDP45)................................................................................51

Figure 56: Safety reports – vehicles (CDP09)...............................................................................52

Figure 57: Range of ambient temperature during vehicle operation (CDP21) .............................52

Figure 58: Fuel cell start times from sub-freezing soak conditions (CDP05)...............................53

Figure 59: Time between trips & ambient temperature (CDP19).................................................53

Figure 60: Difference between tank and ambient temperature prior to refueling (CDP72)..........54

Figure 61: Vehicle operating hours (CDP22)................................................................................54

Figure 62: Vehicles vs. miles traveled (CDP23)...........................................................................55

Figure 63: Cumulative vehicle miles traveled (CDP24) ...............................................................55

Figure 64: Onsite hydrogen production efficiency (CDP13) ........................................................56

Figure 65: Onsite hydrogen production efficiency vs. capacity utilization (CDP60)...................56

Figure 66: Learning Demonstration vehicle greenhouse gas emissions (CDP62)........................57

Figure 67: Refueling station compressor efficiency (CDP61)......................................................57

Figure 68: Hydrogen production cost vs. process (CDP15)..........................................................58

Figure 69: Hydrogen quality index (CDP27)................................................................................58

Figure 70: Hydrogen fuel constituents – all (CDP28)...................................................................59
vi

Figure 71: Hydrogen fuel constituents – sulfur (CDP28) .............................................................59

Figure 72: Hydrogen fuel constituents – total hydrocarbons (CDP28).........................................60

Figure 73: Hydrogen fuel constituents – total halogenates (CDP28)............................................60

Figure 74: Hydrogen fuel constituents – particulate concentration (CDP28)...............................61

Figure 75: Hydrogen fuel constituents – oxygen (CDP28)...........................................................61

Figure 76: Hydrogen fuel constituents – nitrogen (CDP28) .........................................................62

Figure 77: Hydrogen fuel constituents – nitrogen + helium + argon (CDP28).............................62

Figure 78: Hydrogen fuel constituents – particulate size (CDP28)...............................................63

Figure 79: Hydrogen fuel constituents – helium (CDP28)............................................................63

Figure 80: Hydrogen fuel constituents – water (CDP28)..............................................................64

Figure 81: Hydrogen fuel constituents – formic acid (CDP28) ....................................................64

Figure 82: Hydrogen fuel constituents – formaldehyde (CDP28) ................................................65

Figure 83: Hydrogen fuel constituents – CO (CDP28).................................................................65

Figure 84: Hydrogen fuel constituents – CO2 (CDP28)................................................................66

Figure 85: Hydrogen fuel constituents – total (CDP28)................................................................66

Figure 86: Hydrogen fuel constituents – argon + nitrogen (CDP28)............................................67

Figure 87: Hydrogen fuel constituents – argon (CDP28)..............................................................67

Figure 88: Hydrogen fuel constituents – ammonia (CDP28)........................................................68

Figure 89: Infrastructure maintenance (CDP30)...........................................................................68

Figure 90: Hydrogen fueling station maintenance by system (CDP63)........................................69

Figure 91: Safety reports – infrastructure (CDP20)......................................................................69

Figure 92: Primary factors of infrastructure reports (CDP37) ......................................................70

Figure 93: Average refuelings between infrastructure safety reports (CDP35)............................70

Figure 94: Type of infrastructure safety report by quarter (CDP36) ............................................71

Figure 95: Refueling times (CDP38).............................................................................................71

Figure 96: Refueling amounts (CDP39)........................................................................................72

Figure 97: Refueling rates (CDP18)..............................................................................................72

Figure 98: Fueling rates – communication and non-communication fills (CDP29).....................73

Figure 99: Fueling rates – 350 and 700 bar (CDP14) ...................................................................73

Figure 100: Refueling data by year (CDP52)................................................................................74

Figure 101: Hydrogen tank level at refueling (CDP40)................................................................74

Figure 102: Refueling tank levels – medians (CDP41).................................................................75

Figure 103: Refueling by time of day (CDP42)............................................................................75

Figure 104: Refueling by time of night (CDP50)..........................................................................76

Figure 105: Refueling by day of week (CDP43)...........................................................................76

Figure 106: Cumulative hydrogen produced or dispensed (CDP26) ............................................77
1

1 Project Background and Current Status

1.1 Introduction 

This report documents and discusses key results based on data through December 2009 from the 

U.S. Department of Energy’s (DOE’s) Controlled Hydrogen Fleet and Infrastructure Validation 

and Demonstration Project, also referred to as the National Fuel Cell Electric Vehicle (FCEV) 

Learning Demonstration. This report serves as one of many mechanisms to help transfer 

knowledge and lessons learned within various parts of DOE’s hydrogen program as well as 

externally to other stakeholders. It is the fourth such report in a series, with previous reports 

being published in July 2007 [1]

, November 2007 [2], and April 2008 [3]. Other mechanisms have 

included: briefings to FreedomCAR and Fuels technical teams, detailed data and methodology 

discussions with our industry partners, presentations at technical conferences, postings of 

individual results on the National Renewable Energy Laboratory’s (NREL’s) Web site, 

presentations at DOE’s Annual Merit Review, and participation in groups such as the California 

Hydrogen Business Council, the California Fuel Cell Partnership, and various U.S. Fuel Cell 

Council working groups.

NREL has now analyzed data from almost five years of the seven-year project. During this time, 

144 vehicles have been deployed, 23 project refueling stations were placed in use, and no 

fundamental safety barriers have been identified. We have analyzed data from over 436,000 

individual vehicle trips covering 2,500,000 miles traveled and over 130,000 kg hydrogen 

produced or dispensed. Key objectives of the project are to evaluate fuel cell durability, vehicle 

driving range, and on-site hydrogen production cost. This evaluation is performed through 

validating the use of FCEVs and hydrogen refueling infrastructure under real-world conditions 

using multiple sites, various climates, and a variety of hydrogen sources. See Figure 1 for

photographs of the first- and second-generation vehicles and structure of the industry teams 

providing NREL data and Figure 2 for examples of the four types of hydrogen refueling stations

used in the project. 

This report also marks a transition with the makeup of the industry participants who initiated the 

project in 2004. The projects started with four automotive original equipment manufacturers 

(OEM) and energy partner teams. Since that time, DOE’s California Hydrogen Infrastructure 

Project executed by Air Products began providing data, and additional hydrogen fueling 

infrastructure is being installed in California under state and local funding that will also be 

providing data to NREL. We have also seen the completion of the project for two of the four 

original OEM and energy partner teams, who provided their last data by early 2010. New 

analytical results generated after this report will need to be different, given the fact that there are 

only two automotive companies now providing data, and their sensitive data still need to be 

protected. Therefore, while this report is not a final report for the project, it is potentially the last 

comprehensive report to provide new commentary on the data involving all four automotive 

OEM teams up to December 2009.
2

Figure 1: Photographs of the industry partners providing data to NREL on hydrogen fuel 

cell electric vehicles and fueling infrastructure included in this report (Photo credit: Keith 

Wipke)

Gen 1

Gen 2

Gen 2

Gen 1

(CHIP)

Gen 1 & 2

Gen 1 Gen 2

Daimler, BP GM, Shell

Chevron, 

UTC Power,

Hyundai-Kia

Air Products

Ford, BP
3

Figure 2: Four examples of hydrogen production and refueling facilities (Photo credit: 

Keith Wipke)

The three high-level objectives of this project are to validate hydrogen FCEVs and infrastructure 

against the following targets:

• 250-mile range

• 2,000-hour fuel cell durability

• $3/gge hydrogen production cost (based on volume production). 

NREL works to provide DOE and industry with maximum value from the data produced by this 

“learning demonstration.” We seek to understand the progress toward the technical targets, and 

provide that information to the Fuel Cell Technologies (FCT) program research and development

(R&D) activities. This information will allow the program to move more quickly toward costeffective, reliable hydrogen FCEVs and the supporting fueling infrastructure.

1.2 Approach 

NREL’s approach to accomplishing the project’s objectives is structured around a highly 

collaborative relationship with each of the industry teams: Chevron/Hyundai-Kia, Daimler/BP, 

Ford/BP, GM/Shell, and Air Products. We are receiving raw technical data on both the hydrogen 

vehicles and the fueling infrastructure that allows us to perform unique and valuable analyses 

across all teams. Our primary objectives are to feed the current technical challenges and 

opportunities back into the DOE Fuel Cell Technologies Program and assess the current status 

and progress toward targets.

To protect the commercial value of these data for each company, we established the Hydrogen 

Secure Data Center (HSDC) at NREL to house the data and perform our analysis. Figure 3

shows the flow of data and results, overlaid on top of the quantity of data received at the HSDC. 

Delivered Liquid Hydrogen

Irvine, CA

Mobile Refueler

Sacramento, CA

Steam Methane Reforming

Oakland, CA

Delivered

Compressed H2

Natural Gas

Onsite Reforming Electrolysis

Delivered 

Liquid H2

Onsite Electrolysis

West Los Angeles, CA
4

To ensure value is fed back to the hydrogen community, we publish composite data products

(CDPs) twice a year at technical conferences. These data products report on the progress of the 

technology and the project, focusing on the most significant results. Additional CDPs are

conceived as additional trends and results of interest are identified. We also provide our detailed 

analytical results from each individual company’s data back to them to maximize the industry 

benefit from NREL’s analytical work and obtain feedback on our methodologies. These 

individual company results are not made available to the public.

Figure 3: Data flow for Hydrogen Secure Data Center (HSDC) analysis and results, 

overlaid on top of quantity of data received at HSDC

In order to be able to evaluate such a large data set, NREL developed an in-house tool called the 

Fleet Analysis Toolkit (NRELFAT), which helped organize and automate the various analyses 

being performed on both the vehicles and the infrastructure. Figure 4 shows a screen capture of 

the initial screen. The tool has recently undergone a major rework to allow the analysis 

functions to be applied not only to FCEVs, but also to fuel cell buses, fuel cell forklifts, 

laboratory fuel cell data, backup fuel cells, stationary fuel cells, and plug-in hybrid vehicles. The 

overall functionality of the NRELFAT has been covered in previous publications, so it will not 

98657

436315

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

# Trips

Size of Data (MB)

Cumulative On-Road Data Received for 

Fuel Cell Vehicle Learning Demonstration

MB of data

# trips

Through June 2010:

436,000 individual vehicle trips

98 GB of on-road data

Composite 

Data 

Products

Detailed 

Data 

Products

NREL

HSDC
5

be discussed in detail here. Having such a sophisticated tool in-house allowed us to rapidly 

respond to DOE’s and the Department of Defense’s needs for evaluation of early market fuel cell 

applications.

Figure 4: Introductory screen of NREL’s Fleet Analysis Toolkit.

1.3 Status

Industry teams were selected by DOE for this project in April 2004. The first data started 

flowing to NREL in September 2004 after DOE had signed cooperative agreements with the 

industry partners. Since that time, as shown in Figure 3, data has been flowing continuously to 

NREL on a monthly or quarterly basis from the teams. The project was originally scheduled to 

be completed in September 2008, but was extended through September 2009. Two of the teams, 

Ford/BP and Chevron/Hyundai-Kia, completed their projects as scheduled in September 2009, 

while two other teams led by Daimler and GM continued beyond that time with a new scheduled 

completion date of September 2011. There will be 40 vehicles evaluated in the final portion of 

this project to track performance improvements from the latest technology. By the end of the 

project, it is anticipated a cumulative total of 170 vehicles will have been evaluated.

This transition is reflected in some of the CDPs, which show the number and status of FCEVs 

(Figure 5) and hydrogen fueling stations (Figure 6 and Figure 7). As shown in Figure 5, there 

were a gradual number of vehicles retired through 2008 (approximately 20 vehicles), with a 
6 

much larger number retired by the fourth quarter of 2009, when the two teams completed their 

projects. Notice that all of the first-generation vehicles utilizing 350-bar pressurized hydrogen 

storage or liquid hydrogen have now been retired with only 700-bar storage vehicles continuing 

to operate. 

Figure 5: Cumulative number of vehicles deployed, by hydrogen storage type and status 

Figure 6 shows the cumulative number of stations deployed as 23. Of those 23, as of December 

2009, 8 have been decommissioned, 10 are continuing operation outside of the project, and 5 are 

continuing within the project. However, several of the 10 that are shown as continuing outside 

of the project are expected to be decommissioned in 2010. Figure 7 shows the type of 

production or delivery technology demonstrated by each station. The highest number of stations 

used delivered compressed hydrogen, followed by on-site electrolysis. Over half of the 

electrolysis stations have been retired, whereas only one of the five on-site natural gas 

reformation stations has been retired. 

While many of the project stations may come to the end of their useful demonstration life in the 

next few years, many new or upgraded stations are being opened in California as a result of the 

combined efforts of the California Air Resources Board, the California Energy Commission, and 

the South Coast Air Quality Management District. These new stations are helping provide a 

bridge from the early demonstration stations (from the Learning Demonstration and other 

demonstrations) to a point in the future when the number of FCEVs is large enough to create a 

market pull for private sector investment. 

83

40

17

-

20 

40 

60 

80 

100 

120 

140 

160 

Cumulative Vehicles Deployed/Retired1

Vehicle Deployment by On-Board Hydrogen Storage Type

700 bar on-road

350 bar on-road

Liquid H2 on-road

700 bar retired

350 bar retired

Liquid H2 retired

(1) Retired vehicles have left DOE fleet and are no longer providing data to NREL

Some project teams concluded in Fall/Winter 2009 Created Mar-09-2010 8:34 AM

144

NREL CDP25

17 vehicles on road

127 retired

40

83

4
7 

Figure 6: Cumulative stations commissioned with current status 

 

Figure 7: Type and number of hydrogen stations with current status 

8

10

5

0

5

10

15

20

25

Number of Stations

Reporting Period

Cumulative Stations

Existing Stations

Continuing Outside of Project

Retired Stations

NREL CDP31

Created Mar-19-10 9:05am

5

10

8

0

1

2

3

4

5

6

7

8

9

Delivered Compressed 

H2

Natural Gas On-site 

Reforming

Electrolysis Delivered Liquid H2

# of Stations

Production Technology

Infrastructure Hydrogen Production Methods 

Existing Stations

Continuing Outside of Project

Retired Stations

NREL CDP32

Created Mar-19-10 9:05am
8

In order to obtain a variety of data, the project included geographically diverse locations for 

demonstration of the vehicles and infrastructure. Initially, there were five regions of the country 

involved, including the San Francisco Bay area, the Los Angeles area, the Detroit area, Orlando, 

and a corridor from Washington, DC, to New York. In the last year, as two of the teams 

completed their portions of the project, some of the stations have been decommissioned, 

including all of the stations in Florida. The current project (and other) stations in the United 

States are shown in Figure 8.

Figure 8: Current location of hydrogen stations in the United States as of August 2010.

1.4 Key NREL Analysis Accomplishments in FY 2010

• Created and published 80 CDPs (the ninth and largest set of public results) representing 

results from analyzing almost five years of Learning Demonstration data. See Figure 9

for thumbnail images of all 80 results.

• Received and processed data from a total of 436,000 individual vehicle trips, amounting 

to over 98 GB of on-road data, since inception of the project.

• Documented and archived each quarter’s analysis results in the NRELFAT GUI.

• Executed NRELFAT to produce detailed data results and CDPs in parallel for easier 

industry and internal review.

Aug-10-2010

3

58

8

SF Bay Area

DC to New York

5

Detroit Area

Los Angeles Area

15
9 

• Presented project results publicly at the Fuel Cell Seminar, the California ZEV 

Technology Forum, the National Hydrogen Association conference, the World Hydrogen 

Energy Conference, and the 2010 DOE Fuel Cell Technologies Program Merit Review 

meeting. 

• Maintained NREL’s Web page at http://www.nrel.gov/hydrogen/cdp_topic.html to allow 

direct public access to the latest CDPs organized by topic, date, and CDP number. 

• Provided presentations of results to key stakeholders, including two FreedomCAR and 

Fuel technical teams (storage and fuel cells). 

• Leveraged NREL tools and capabilities to enable analytical results to be generated from 

fuel cell forklifts and other early-market fuel cell applications. 

Figure 9: Thumbnail images of the 80 CDPs published in spring 2010 
10 

2 Results 

The results discussed in this report came from analyzing almost five years of vehicle and 

infrastructure data (through December 2009). This resulted in a total of 80 new or updated CDPs 

that were published and could be presented publicly. To accomplish the analysis, we continued 

to improve and revise our in-house fleet analysis tool, NRELFAT. Since there are so many 

technical results from the project, they cannot all be discussed during 15-20 minute conference 

presentations. Therefore, in January 2007 NREL launched a Web page at 

http://www.nrel.gov/hydrogen/cdp_topic.html to provide the public with direct access to the 

results (see Figure 10 for a screen capture of this Web page). The Web site makes current and 

archived CDPs available to the public. Highlights from the most recent CDPs were presented 

publicly at the National Hydrogen Association conference and the DOE Annual Hydrogen 

Program Merit Review as the Spring 2010 Results. In order to focus on high-level results, 

conclusions, and trends, this report will discuss the results in bullet form, organized by technical 

topic. The last section includes all of the CDPs in the order they are referenced. 

Figure 10: Screen capture from NREL's composite data product Web site 
11

2.1 Vehicle Results 

• Fuel Cell System Efficiency: Researchers from the car companies measured fuel cell 

system efficiency from select vehicles on a vehicle chassis dynamometer at several 

steady-state points of operation. NREL worked with the data and the companies to 

ensure that appropriate balance-of-plant electrical loads were included. This ensured that 

the results were comparable to the target and based on the entire system rather than just 

the stack. DOE’s technical target for net system efficiency at quarter-power is 60%. 

Baseline data from the four Learning Demonstration teams several years ago showed a 

range of net system efficiency from 51% to 58% for first-generation systems, which was

very close to the target. As second-generation vehicles were introduced, the companies 

also performed baseline dynamometer testing that revealed an efficiency of 53% to 59%

at quarter-power, within one percentage point of the target. Since the last progress report 

was published, we have also expanded this CDP to include a comparison of the efficiency 

at full power, where DOE’s target was 50% net system efficiency (Figure 12). The data 

show first-generation systems as having 30% to 54% efficiency full power while secondgeneration systems have 42% to 53 % efficiency, exceeding the 50% target. 

Additionally, we published the ranges of efficiency data from the four teams with the two 

shaded green sections, showing that Gen 2 data are more closely clustered than Gen 1 

data. 

• Fuel Cell Operating Points: Since a fuel cell system’s peak efficiency is normally at low

powers (typically 10% to 25%), we evaluated the fuel cell system operation from a 

number of different perspectives to better understand whether the unique performance 

characteristics of the fuel cell system were being maximized. As reported in the last 

progress report [3]

, a significant amount of time is being spent at low fuel cell system 

power (Figure 13). In fact, the teams’ average amount of time spent at <5% of peak 

power was over 50%. We subsequently subdivided these bars into the time with zero 

speed (new since last progress report) to show that almost all of the time with zero speed 

is at less than 10% fuel cell system power. However, for overall vehicle fuel efficiency, 

the amount of energy spent at various power levels and the efficiency at those power 

levels are the critical metrics. We found that much of the fuel cell energy (about 40%) is 

expended at fuel cell power levels between 20% and 50% of peak power (Figure 14). 

This matches up very well with the peak fuel cell system efficiency points (at 

approximately 25% power) previously discussed. Only about 20% of the energy is 

expended at powers less than 15% of peak power, indicating that low power efficiency is 

not as important as the percentage of time spent there would imply. 

• Duty-Cycle Evaluation: In order to understand why so much time was spent at low 

power, we analyzed the lengths of all trips and compared the results to national statistics

(Figure 15). With more than 40% of the Learning Demonstration trips being less than 

one mile, it is clear that the amount of time spent at low fuel cell power is due in part to a 

large number of short trips for which the vehicle is not likely accelerated to higher 

speeds. This differs from the national driving statistics (overlaid with pink diamonds on 

this same graph), which show that only about 10% of the national average trips are less 

than one mile. If a large number of starts/hour is one of the major degradation factors, as 

has been reported at the laboratory scale, then this large number of short driving trips 

could be prematurely shortening the life of the Learning Demonstration fuel cells. 
12

Further investigation is necessary before that linkage can be made based on our analysis 

of the real-world data.

Since then we have received many questions about how the vehicles were driven; 

therefore, we created two new CDPs that compared the Learning Demonstration driving 

with well-known dynamometer drive cycles. Figure 16 compares the distribution of 

operating time to that of four dynamometer drive schedules. We can see that the large 

amount of time spent at 0–5 mph matches most closely to the Japanese 10-15 mode drive 

schedule (40% of time spent in this speed bin), and has a very low percentage of time at 

the higher speeds contained in the HWFET (highway driving) and US06 (aggressive 

acceleration/deceleration) driving schedules. This is not surprising, given that many of 

the vehicles were deployed in congested traffic regions such as New York and Los 

Angeles. We also have a portion of the 0–5 mph bar that shows the zero-speed idle time, 

shown in gray, which makes up about 28% of all Learning Demonstration vehicles’

driving time. Figure 17 compares the distribution of the trip idle time percentages within 

each trip to the same four drive cycles. The Learning Demonstration most closely 

matches the percentage idle of the UDDS (urban driving) cycle with about 12% of the 

trips matching that idle time of about 19%. 

• The Impact of Short Trips: There has been much public attention on the potential for 

plug-in electric vehicles (PEVs) to improve the United States’ oil-dependency situation. 

The Learning Demonstration vehicle data were evaluated to see how these early FCEVs 

were being driven (mostly in fleet operation) and what impact these duty cycles would 

have on plug-in vehicles and potential future plug-in versions of these FCEVs. We first 

looked at the amount of energy consumed by all Learning Demonstration vehicle trips 

(Figure 18) and found that about 35% of the trips required less than 0.5 kWh of energy to 

be produced by the fuel cell system (red FC bar in the figure). This indicates that a 

battery would not require much storage energy to handle several plug-in FCEV trips for 

the Learning Demonstration vehicles, provided that the battery could also provide the 

peak power required and survive the larger swings in state-of-charge. However, this is 

not the entire story, and if the assumption is that PEVs will primarily be recharged slowly 

during off-peak/night times, then these data need to be analyzed with both the daily miles 

traveled (Figure 19) and the amount of time between trips (Figure 20) in mind. 

What we find is that an effective 20-mile electric range would electrify about one-half of 

the Learning Demonstration fleet’s daily miles traveled. However, this would satisfy only 

about one-quarter of the national daily average miles traveled. An effective 40-mile 

electric range would electrify over two-thirds of the Learning Demonstration vehicle 

miles, and just over half of the national daily miles traveled. While the large number of 

Learning Demonstration vehicle “hot-starts” could be beneficial for fuel efficiency of a 

FCEV (about 60% of trips occur within one hour of the previous trip), this also indicates 

that there may be limited opportunities for daytime opportunity charging (almost 60% of 

the trips are separated by less than one hour, and half of those are separated by less than 

10 minutes). Having an engine [internal combustion engine (ICE) or fuel cell] on-board 

increases the ability to electrify the maximum number of miles and discharge the battery 

without being forced to recharge during the day for fear of running out of charge before 

evening. The bottom line is that a thorough analysis of actual target-market duty cycles 

must occur for the benefits of PEVs to be understood, preferably through using actual 
13

PEV fleets and recharging behavior. Such an evaluation has been initiated by DOE’s 

Vehicle Technologies Program. 

• Vehicle Fuel Economy: Vehicle fuel economy was measured using city and highway 

drive-cycle tests (Figure 21) on a chassis dynamometer using draft SAE J2572 (left two 

bars, representing the range of four points, one from each OEM). These raw test results 

were then adjusted according to U.S. Environmental Protection Agency (EPA) methods

to create the “window-sticker” fuel economy that consumers see when purchasing the 

vehicles (0.78 x Hwy, 0.9 x City) (center two bars). This resulted in an adjusted fueleconomy range of 42 to 57 miles/kg hydrogen for the four teams for first-generation 

vehicles, as compared to 43 to 58 miles/kg for second-generation vehicles. As with all 

vehicles sold today, including gasoline hybrids, actual on-road fuel economy is slightly 

lower than this rated fuel economy (right two bars). The on-road fuel economy spans the 

range of 31 miles/kg hydrogen to 45 miles/kg hydrogen for Gen 1 and 36 to 52 miles/kg 

hydrogen for Gen 2. This last comparison shows an important finding, which is that Gen 

2 vehicles have been made quite a bit more robust to allow higher fuel economy (relative 

to Gen 1) to be obtained even when driven under all different kinds of conditions. 

Note that the EPA has adjusted its testing and reporting methodology, beginning with 

model-year 2008 vehicles, to try to make the window-sticker fuel economy better reflect 

on-road driving performance, but this project is using the EPA adjustment that was in 

place when the vehicles were introduced to avoid performing retests or applying the new 

corrections that have not been validated for application to hydrogen FCEVs.

• Vehicle Driving Range: Vehicle driving range was calculated using the fuel economy 

results discussed above and multiplying them by the usable hydrogen stored onboard 

each vehicle (Figure 22). Using the EPA-adjusted fuel economy resulted in a firstgeneration vehicle range in FY 2008 from just over 100 miles up to 190 miles from the 

four teams. The second-generation vehicles subsequently pushed this range higher, to 

196 to 254 miles using 700-bar storage and met the DOE 250-mile range objective

established for this project. In June 2009, an on-road driving range evaluation was 

performed in collaboration with Toyota and Savannah River National Laboratory. The 

results indicated a 431-mile on-road range was possible in southern California using 

Toyota’s FCHV-adv FCEV [4]

. More recently, the significant on-road data obtained from 

second- and first-generation vehicles allowed a comparison of the real-world driving 

ranges of all the vehicles in the project (Figure 23). The data show that there has been a 

45% improvement in the median real-world driving range of second-generation vehicles 

(81 miles) as compared to first-generation (56 miles), based on actual distances driven 

between over 25,000 refueling events. Obviously, the vehicles are capable of two to three 

times greater range than this, but the median distance travelled between refuelings is one 

way to measure the improvement in the vehicles’ capability and the way in which they 

are actually being driven. 

Two other CDPs relating to range were also generated and previously reported on. 

Figure 24 shows a histogram of the distance vehicles actually traveled between fuelings 

as a percentage of each vehicle’s dynamometer range. This shows that the majority of 

the vehicles (75%) travel less than 50% of the dynamometer range between fuelings. 

This is due to several factors, but the dominant ones are limited hydrogen infrastructure, 

fear of running out of fuel, and actual on-road fuel economy being lower than the 
14

dynamometer fuel economy, as has already been discussed. Figure 25 shows the on-road 

range of the four teams (green bars) as a percentage of their dynamometer range. The 

spread of this on-road range has decreased significantly for Gen 2 (light green) compared 

to Gen 1 (dark green), showing this robustness to driving styles relative to vehicle fuel 

economy and subsequent range even more clearly that in the fuel economy CDP. 

• On-Board Hydrogen Energy Storage System Status: Storage data were reported to NREL 

using a hydrogen storage system spreadsheet. This spreadsheet includes the breakdown 

of the mass and volume due to the hydrogen itself, the pressure vessel, and the balanceof-plant. The balance-of-plant category includes:

o Controls and measurement (hydrogen storage-specific electronics)

o Fuel delivery to power plant (plumbing)

o Hazard mitigation components [hydrogen sensors, pressure release devices 

(PRDs)], venting)

o Fueling equipment (filters, nozzle receptacle, piping, communications, grounding)

o Mounting brackets, auxiliary equipment (thermal management, etc.). 

Figure 26 shows the difference in the ranges of mass (as a percentage of the total mass) 

stored in the teams’ 350-bar and 700-bar systems. We can see the potential for the 

percentage of system mass to increase in the second-generation systems, but we need to 

realize that the second-generation (700-bar) systems also typically have the benefit of 

economies of scale because they will have a larger total mass of hydrogen stored to meet 

customer range expectations. 

Figure 27 shows the same type of 350-bar vs. 700-bar comparison but for the volumetric 

capacity (how much hydrogen can be stored per storage system volume). This is where 

the advantage of going to a higher pressure really shines, showing the potential for a 

significant increase in the mass of hydrogen stored per liter, making the packaging of the 

system on a vehicle more attractive. 

Finally, the percentage breakdown by each of these categories was averaged across the 

four teams so that pie-charts of the differences between 350 bar and 700 bar could be 

examined for the mass and volumetric characteristics (Figure 28). The comparison 

shows that while the average hydrogen weight percentages are similar for 350 and 700 

bar (within 1%), and the pressure vessel and balance-of-plant for 700 bar take up a larger 

percentage of the system volume, the 700-bar systems ultimately allow for a more 

compact package and extended range. Figure 29 shows the tank cycle life, which now 

includes second-generation data and shows some improvement in tank cycle life, still far 

exceeding DOE’s cycling goals set for advanced materials-based technologies.

• Fuel Cell System Power Density and Specific Power: DOE’s target for fuel cell system 

power density in 2010 and 2015 is 650 W/L and for fuel cell system specific power is 

650 W/kg. System level data were gathered from the fuel cell teams and aggregated into 

ranges for first- and second-generation systems separately. First-generation fuel cell 

systems had a specific power of 183 to 323 W/kg, while second-generation systems 

improved to the range of 306 to 406 W/kg (Figure 30). Fuel cell system power density

(Figure 31), on the other hand, stayed the same or dropped slightly (staying in the range 

of 300 to 400 W/L), perhaps because the Gen 2 systems had more balance of plant in 

order to support the freeze tolerance required.
15

Because of the attention that plug-in hybrid vehicles were getting, we were asked to 

generate fuel cell system power density and specific power results that also included the 

hydrogen storage, and then compare to the FreedomCAR targets. We found that while 

Gen 1 to Gen 2 showed significant progress (Figure 32), the 178 to 261 W/kg was still 

shy of the 325 W/kg FreedomCAR research goal when the hydrogen storage system was 

included. The fuel cell system power density (Figure 33), when the hydrogen storage 

was included, came extremely close (with both Gen 1 and Gen 2) to satisfying the 2010 

and 2015 FreedomCAR research goal of 220 W/L (Gen 1 was 152 to 214 W/L, and Gen 

2 was 127 to 213 W/L). This indicates that fuel cell systems are a relatively compact 

means of storing both energy and power relative to batteries.

• Fuel Cell Durability: Fuel cell stacks will need roughly a 5,000-hour life to enter the 

market for light-duty vehicles. For this demonstration project, targets were set by DOE at 

1,000 hours in 2006 and 2,000 hours in 2009. Results were first published in the fall of 

2006. These results were relatively preliminary because most stacks at that time only had 

a few hundred hours of operation or less accumulated on-road. Since DOE’s target for 

2006 was 1,000 hours, NREL developed a methodology for projecting the gradual 

degradation of the voltage based on the data received to date. This involved creating 

periodic fuel cell polarization curve fits from the on-road stack voltage and current data 

and calculating the voltage under high current. This enabled us to track the gradual 

degradation of the stacks with time and do a linear fit through each team’s data. We then 

compared these results to the first-generation target of 1,000 hours for 2006. 

Since those initial evaluations, many improvements have been made in NREL’s fuel cell 

durability analysis methodology, including using a two-segment linear fit and using a 

weighting algorithm to come up with a more robust and automatic fleet average. Now 

that the data submissions are complete on first-generation stacks (no new first-generation 

stack data is being received), we can make some final conclusions about that generation 

of technology. The maximum number of hours a first-generation stack has accumulated 

without repair is 2,375, which is the longest stack durability from a light-duty vehicle 

FCEV in normal use published to date (see left blue bar in Figure 34). As shown in 

Figure 35, on average, the slope of the initial power degradation is steeper in the first 200 

hours and becomes more gradual after that. We also found that around 1,000 hours of 

data were required to reliably determine the slope of the more gradual secondary 

degradation. Finally, with significant drops in power observed at 1,900–2,000 hours, it 

appears as though this is a solid upper bound on first-generation stack durability

(characterizing 2003-2005 technology). 

For second-generation fuel cell stacks (2005-2007 technology), the range of maximum 

hours accumulated from the four teams is now approximately 800 to over 1,200 hours

(Figure 34), with the range of team average hours accumulated of approximately 300 to 

1,100 hours. Relative to projected durability, the Spring 2010 results indicate that the 

highest average projected team time to 10% voltage degradation for second-generation 

systems was 2,521 hours, with a multi-team average projection of 1,062 hours. Therefore, 

the 2,000-hour target for durability has been validated. Figure 36 shows that less data 

have been gathered on second-generation stacks (approximately 1,100 hours at most),

and so the 10% durability projections are less certain for Gen 2 stacks than Gen 1 stacks. 

The continuation of the project into 2011 will allow more durability data to be gathered.
16

Note that the 10% criterion, which is used for assessing progress toward DOE targets, 

may differ from the OEM’s end-of-life criterion and does not address “catastrophic” 

failures such as membrane failure. We received many questions about the 10% voltage 

degradation value (some people felt it might be too aggressive), and so we varied the 

voltage drop allowed out to 30% to show the sensitivity to this value. As you can see in 

Figure 37, the diamond values on the left are the same as the average projections from 

Figure 34. The projected hours then increase as the voltage drop constraint is 

successively relaxed. The primary reason why the Gen 2 curve does not rise as fast as the 

Gen 1 curve is due to the fact that less data have been received for Gen 2, and so we have 

some limitations on the projection that are based on the quantity of data received to limit 

the extent of the extrapolations. For Gen 1, which has more data and fewer 

extrapolations, increasing the percentage from 10% to 30% roughly doubles the projected 

time to that voltage drop.

In addition to analyzing voltage drop, we examined the stack power drop since that is 

what is ultimately converted into propulsion through the electric motor. Figure 38 shows 

histograms for Gen 1 and Gen 2 percentage power drop for each stack, and the stacks’ 

status. One thing you can see for Gen 1 is that many stacks had a power drop of over 

40% before being retired, and some of those stacks continue to be operational. Both of 

the Gen 2 stacks that have been retired exhibited a high power drop (greater than 40%), 

with a lot of the Gen 2 stacks ranging between 10% and 20% power drop. Since we 

calculated each stack’s power drop, we were asked to examine the time to OEMacceptable power drops where each OEM provided an acceptable percentage for its 

vehicles. Figure 39 shows these results, with an additional distinction of separating out 

the projections that were made from stacks with less than 200 hours from those with 

more than 200 hours. In general, many of the low projections are based on stacks with 

low operating hours for both Gen 1 and Gen 2. Comparing to the 2009 2,000-hour target, 

27% of Gen 1 stacks exceeded that projection, and 17% of Gen 2 stacks exceeded it. As 

previously mentioned, more Gen 2 data are required to fully assess the durability of the 

second-generation systems, as can be seen in the stack-hour histogram shown in Figure 

40, which also shows that only two Gen 2 stacks have been removed for low 

performance. The blue bars indicate the stacks that are no longer accumulating hours, but 

were not removed due to low performance. Most of these stacks that stopped 

accumulating data were due to the project teams that concluded at the end of 2009 or 

whose host vehicles were retired for a variety of reasons.

• Factors Affecting Fuel Cell Durability: In addition to evaluating the projected durability 

of the fuel cell stacks in this project, a significant amount of effort was expended in 

characterizing the factors that might be having a strong effect on the durability.

The first area of focus was on startup and shutdown of the fuel cell. While some vehicles 

may shut off the stack during idle or coast-down, all systems are shut off when the 

vehicle is turned off. In the laboratory, this has been shown to be one of the degradation 

mechanisms, and, given the large number of short trips discussed earlier, we wanted to 

quantify how frequently the field data showed startups and shutdowns. Therefore, we 

quantified the number of trips (meaning a key-on to key-off) per hour (Figure 41) and 

found a relatively normal distribution around three to four trips per hour. This data was 

requested by researchers in order to calibrate their accelerated testing against what was 
17

being seen in the field. We also wanted to see if the stacks that were demonstrating long 

life had more or fewer starts than those that had not yet achieved long life. Figure 42

shows the same trip/hour data as a function of stack operating hours (binned into 250-

hour operating hour groups). These results show that the stacks that have accumulated up 

to 2,000 hours did have fewer trips per hour (about half), but this correlation alone does 

not establish a causal relationship between fewer trips per hour and long life.

We embarked upon a multivariate study in 2007 to determine the dominant factors that 

are affecting the rates of degradation. We started out by creating a database of all of the 

Learning Demonstration stacks and various performance attributes. Each individual 

stack was examined for the hours of data accumulated to date and the confidence in the 

fit of the degradation slope. We then manually removed about one-third of the stacks 

from the degradation factors analysis to try to have as clean a data set as possible for the 

analysis. The database included the following key factors for each stack:

o Average voltage degradation rate (key dependent variable)

o Ambient temperature

o Time at various voltages

o Time at various currents

o Number of cold and hot starts (based on time between trips)

o Idle time

o Trip length

o Average number of stack starts/hour.

After trying many techniques, we focused on partial least squares regression (PLS) 

analysis because it was the most direct way of measuring how much of the variance in 

voltage degradation could be explained by specific groups of factors. We first performed 

the PLS on the stack data from all four teams to see if there were any overall trends that 

covered all of the technology involved (Figure 43). The trends across all four teams were 

not strong, which we soon discovered was because the trends among the companies were 

often different. 

Next we looked at each team’s data individually and performed the same PLS analysis

(Figure 44). The connection between voltage degradation rate and the variables 

improved, and we were able to pull out groupings of factors that appeared to cause either 

higher or lower than average decay rates within each team. Note that the teams’ PLS 

models have a high percentage of explained decay rate variance, but the models are not 

very robust and results are scattered. We found that while there were some common 

factors among several teams’ results, there were also normally contradictory trends from 

one of the teams (an example of this conflicting trend is for high voltage time and low 

current time for team four vs. team two). The multivariate effort was put on hold for 

about a year, but we hope to include some of the new voltage cycling information 

(described next) and rerun the multivariate analysis. This work was done in close 

collaboration with each of our industry partners, who have also had challenges extracting 

dominant factors from the field data. If NREL is able to identify some of the dominant 

factors from the field data, we will see if there are opportunities to feed this back into the 

companies’ research as well as into DOE’s R&D program.

In discussions with fuel cell researchers, the voltage cycling of the stack was identified as 

something that would be worth the team investigating further. Prior to this, only the 
18 

amount of time spent at different voltages was evaluated (Figure 45), and not the rate of 

change of the voltage or the number of times the voltage changed. Figure 11 shows the 

overall approach we used to 1) define a voltage transient cycle, 2) find voltage transient 

cycles in the on-road stack data, and 3) categorize and collect voltage transient cycle 

details. 

Figure 11: Approach for characterizing voltage transient cycles 

 

Looking at the data graphically (Figure 46), we see a relatively symmetric distribution of 

the magnitude of voltage change about 0, with most of the changes lasting less than 15 

seconds. Once we had the voltage cycles characterized, the first thing we noticed was 

that the number of cycles per trip mile (and per trip minute) was drastically reduced 

between Gen 1 and Gen 2 for at least one team by a factor of 4 (Figure 47). We found 

that the dominant transient cycle category was the “SlowDown” category (Figure 48), 

which was a slow voltage drop followed by a fast voltage rise. This could come from a 

gradual acceleration of the FCEV, followed by taking the foot off the accelerator pedal 

due to traffic at a stop sign or light. The frequency of each of these five cycle categories 

is now available to us as a new input to our multivariate analysis. Figure 49 shows the 

same characterization, but includes the relative magnitude change in voltage rather than 

the rate of voltage change. Using this same data analysis technique, we took the subset of 

“steady-state” transients, which had a drop in voltage followed by a period of relative 

steady-state voltage, and evaluated the amount of trip time the stacks spent in this 

condition of steady state (Figure 50). The results showed that the most common bin was 

the 10–15% of time being held at steady state, but with some trips getting up to as high as 

50% of the time at steady state. Finally, we also examined the number of the voltage 

1) Define a voltage transient cycle

dV1

dV2

dT dTss

dVss

time

voltage

Cycle Definition:

dV >= 10% Nom Stack V

dTss >= 10 sec

dVss <= 5% Nom Stack V

2) Find voltage transient cycles

0 500 1000 1500 2000 2500 440

460

480

500

520

540

560

580

600

620

data pt

voltage

EcoCars Trip Fuel Cell Voltage

FC Volt

Transient Pt

Created: Mar-01-10 3:33 PM

50 100 150 200 250

460

480

500

520

540

560

580

600

dt t

g

EcoCars Trip Fuel Cell Voltage

FC Voltage in Trip

FC Voltage in Trip

(a) (b) (c) (d) (e)

voltage

time

3) Categorize and collect voltage 

transient cycle details

Cycle Categories
19

cycles that were outside of a threshold between 70 and 90% of maximum stack voltage 

(Figure 51). We found that these more extreme voltage transients occurred on average 

less than twice per mile (accounting for about one-quarter of all voltage transients), with 

the drop below 70% maximum stack voltage occurring more times per mile than the rise 

above 90% maximum stack voltage.

• Fuel Cell System Maintenance: New since the last progress report is an evaluation of the 

fuel cell maintenance by system (Figure 52). We can see that only one-third of the FCEV 

maintenance events were due to the fuel cell system, while one-half of the labor hours 

were attributed to repairing the fuel cell system. Breaking down the maintenance events 

related to the fuel cell system, we find that 39% were associated with the thermal 

management, 23% with the air system, 13% with controls/electronics/sensors, 12% with 

the fuel system, and only 10% with the fuel cell stack itself. This indicates that the 

balance-of-plant needs some attention as the vehicles get closer to being a product for the 

marketplace if they are to meet customer expectations for reliability.

• Time of Day Vehicles Are Driven: Some questions were asked early in the project about 

whether the Learning Demonstration vehicles are being driven like conventional vehicles 

or whether their usage is being too “controlled” to match typical driving behavior. To 

investigate this, we looked at the time of day people initiated their trips and which day of 

the week the trips were occurring on. Figure 53 shows a clock-face radial histogram, 

with the green data representing the time of day when people initiated their trips. 

Overlaid on top of that, we have placed pink diamonds to show the national statistics 

based on the 2001 National Household Travel Survey (NHTS) data. What we find is that 

the Learning Demonstration vehicles are driven at similar times of day to the national 

statistics, with the exception of the late afternoon between 4 and 6 p.m. when the average 

person (nationally) is likely either picking up children from school, driving home from 

work, or running errands. Since the first-generation Learning Demonstration vehicles are 

primarily used for professional or fleet activities, it is not surprising that there would be a 

difference. The percentage of trips taken between 6 a.m. and 6 p.m. corresponds 

relatively closely to the national statistics (85.3% vs. 81.5%). The nighttime driving 

behavior trend is also similar to the national statistics (Figure 54), although there are 

overall more evening trips driven nationally (18.4%) than within the Learning 

Demonstration (14.7%). 

• Day of Week Vehicles Are Driven: We examined the days of the week that people drove 

the Learning Demonstration FCEVs and compared this with the national statistics. 

Figure 55 shows a bar for each day of the week, beginning with Sunday, and overlays a 

diamond symbol for the national statistics. We can easily see that nationally the trips are 

relatively uniform on weekdays, with a slight dip on the weekends, but that the Learning 

Demonstration vehicles are rarely driven on the weekends. Additionally, Learning 

Demonstration vehicles have significantly more trips Tuesday through Thursday as 

compared to Monday and Friday, which does not reflect typical national behavior. While 

the day of the week does not matter to the car’s performance, it might be an indication 

that some of the weekend types of trips (for example: long trips to mountains or lots of 

short trips to the hardware store) are not being captured in this Learning Demonstration 

data set.
20

• Vehicle Safety: The Learning Demonstration has had a very strong safety record to date. 

Figure 56 shows the number and type of vehicle safety reports by quarter. Within the last 

2 years, there have only been two vehicle safety reports, both involving minor hydrogen 

leaks detected during fueling. Prior to this there were four traffic accidents in which

there was no hydrogen released and only minor injuries due to the two-vehicle impact

(not hydrogen related). For the case identified as “tank scratch,” the team determined 

that the tanks had been scratched during service of a nearby system and that the scratches 

could be easily repaired without affecting the safety of the tanks. 

• Vehicle Climate Compatibility: Figure 57 shows the range of ambient temperature during 

vehicle operation spanning –5.8°F to 140°F. Since the last progress report in 2008, this 

CDP has been updated to include a distribution and some statistics. The data show that 

28.2% of the trips were in temperatures hotter than 28°C and only 1.4% of the trips were

in temperatures below 0°C. Clearly, the vehicles are capable of operating in extreme 

temperature conditions. Special tests were performed in cold chambers to determine the

ability of second-generation vehicles to start in sub-freezing temperatures. Figure 58

shows the fuel cell system start times in sub-freezing conditions, with the left two bars 

showing time to drive away, and the right two showing the time to maximum fuel cell 

power. It appears as though at one team has the time to drive away sufficiently short 

(approximately 15 seconds) while one team has some more improvements required (at 

just less than 5 minutes). All of the teams could probably improve their time to 

maximum power, with the fastest team being about a minute and a half and the slowest 

being around 9 minutes. 

We also analyzed the time between trips and classified them by the ambient temperature 

range (Figure 59). This result shows a relative equal spread of the extreme temperatures 

between the different soak times, indicating that vehicles need to be designed for any 

duration of soak at any temperature; however, this data could be used to understand the 

probability of the vehicle being left for various times between trips when optimizing the 

system for energy efficiency. For example, it is 3 times more likely that the vehicle will 

be driven again in less than10 minutes as it is that it will be driven again in 30 to 60 

minutes.

Another climate consideration relates the temperature rise of the tank during fueling, with 

the constraint that the temperature of the tank should never exceed 85°C. We were 

approached by the SAE J2601 committee, which was drafting the standard for filling 

hydrogen vehicles. They had made some assumptions about what the tank temperature 

would be when it arrived at a station to receive fuel, and wanted some real-life data from

this project in order to calibrate their model inputs. Therefore, we created the two graphs 

in Figure 60 to provide them with publicly available data to use. The left graph shows 

that the mean temperature at which the tanks arrive for fueling is –3.8°C below ambient 

temperature, with a standard deviation of 6.1°C. The graph on the right shows a 

frequency surface plot of each of the tank/ambient temperature pairs.

• Other Vehicle Metrics: There are several other vehicle-related CDPs that will be briefly 

mentioned here as they do not logically fall into one of the other categories. Figure 61

shows the distribution of vehicle operating hours, showing a total of over 100,000 hours 

with a median of about 600 hours. The introduction of second-generation vehicles (with 

low hours initially) kept this median from rising much. Similarly, with vehicle miles 
21

traveled (shown in Figure 62), the peak number of vehicles occurs at 10,000 to 15,000

miles. Both of these graphs are now color-coded to indicate the vehicles that are still in 

operation (solid blue) as compared to the vehicles that have been retired (hashed red)

from the project. You can see that the vehicles still in operation are spread relatively 

uniformly across the histograms, with many of the high hour and high mileage vehicles 

being the ones that are still in operation. The fleet has now accumulated over 2.5 million 

miles. Figure 63 shows that after the first few quarters, mileage accumulation has been 

relatively linear, with a slight decrease in slope at the end of 2009 as vehicles began to be 

retired.
22

2.2 Infrastructure Results 

• On-Site Production Efficiency from Natural Gas Reformation and Electrolysis: Detailed 

data on all of the energy inputs required to produce hydrogen on-site were gathered and 

analyzed and compared to DOE’s program targets for 2010 for natural gas reformation 

and 2012 for water electrolysis. The results indicate that natural gas reformation 

efficiency was demonstrated close to the 2010 target of 72% through achieving a best 

quarterly efficiency of 67.7% and a best monthly efficiency of 69.8% (Figure 64 and 

Figure 65). The best quarterly efficiency for water electrolysis was 61.9% with a best 

monthly efficiency of 61.9% (compared to the 2012 target of 69%). Note that targets for 

both of these technologies are for future years (2010 and 2012) and the results from 2005

to 2008 were not yet expected to have achieved future targets. Additionally, the targets 

are set for significantly larger stations (1,500 kg/day of hydrogen) and higher utilization 

(70% capacity factor) than we have in the Learning Demonstration. Figure 65 shows 

that, in general, the efficiency of the systems increases with capacity utilization, and that 

only during a few months were some reformation stations run at between 60 and 70% 

capacity utilization, and that electrolysis stations never had average capacity utilization 

above 35%. The purpose of comparing our actual results to these future targets is to 

benchmark demonstrated progress toward the targets while technical R&D development 

continues to improve the state of the art. 

• Greenhouse Gas Emissions: Greenhouse gas emissions from the Learning Demonstration 

fleet have been assessed and compared to greenhouse gas emission estimates of 

conventional gasoline vehicles. The results indicate that when using hydrogen produced 

onsite via either natural gas reformation or water electrolysis, Learning Demonstration 

hydrogen FCEVs offer significant reductions of greenhouse gas emissions relative to 

conventional gasoline vehicles (Figure 66). Conventional gasoline mid-sized passenger 

vehicles emit 484 g CO2-eq/mile (grams CO2 equivalent per mile) on a well-to-wheels 

(WTW) basis and conventional mid-size SUVs emit 612 g CO2-eq/mi on a WTW basis. 

WTW greenhouse gas emissions for the Learning Demonstration FCEV fleet, which 

includes both passenger cars and SUVs, were analyzed based on the window sticker fuel 

economy of the Learning Demonstration fleet and the actual distribution of hydrogen 

production conversion efficiencies from onsite hydrogen production. Average WTW 

greenhouse gas emissions for the Learning Demonstration fleet operating on hydrogen 

produced from onsite natural gas reformation were 356 g CO2-eq/mi and the lowest 

WTW GHG emissions for on-site natural gas reformation were 237 g CO2-eq/mi. For the 

Learning Demonstration fleet operating on hydrogen produced from onsite water 

electrolysis (including some renewable sources of electricity), average WTW GHG 

emissions were 380 g CO2-eq/mi, with the lowest emissions estimated to be 222 g CO2-

eq/mi for the month with the best electrolysis production conversion efficiency.

• Fueling Station Compressor Efficiency: As part of our analysis of the fuel station 

subsystems, we gathered available data (which was limited) on compressor energy usage 

to evaluate compressor efficiency (Figure 67). We found that on average, the average 

station compressor efficiency (as defined by DOE’s Multi-Year Program Plan [MYPP]) 

was just under 90%, a few points lower than DOE’s targets for 2010 and 2015. The 

compression energy was on average 15.4 MJ/kg, with the best monthly data at 6.4 MJ/kg. 
23

In layman’s terms, this means that on average 11.3% of the energy contained in the 

hydrogen fuel is required for the compression process.

• Hydrogen Production Cost: On-Site Hydrogen Production Cost: Cost estimates from the 

Learning Demonstration energy company partners were used as input to an H2A analysis 

to project the hydrogen cost for 1,500 kg/day early market fueling stations. Results 

indicate that onsite natural gas reformation could lead to a range of $8-$10/kg and onsite 

electrolysis could lead to $10-$13/kg hydrogen cost (Figure 68). While these results do 

not achieve the $3/gge cost target, two external independent review panels commissioned 

by DOE concluded that distributed natural gas reformation could lead to $2.75-

$3.50/kg [4] and distributed electrolysis could lead to $4.90-$5.70 [5]. Therefore, this 

objective was met outside of the Learning Demonstration project.

• Hydrogen Quality: Hydrogen quality was determined by measuring the impurities and 

calculating the hydrogen fuel quality index as a percentage. SAE J2719 has established a 

99.99% hydrogen fuel quality index target. The hydrogen fuel quality index from all the 

stations sampled ranged from 99.73% to 99.999%, as shown in Figure 69. The values on 

the lower end were due to some high detection limits on inert gases, and likely do not 

really represent hydrogen fuel quality that low. Since the last progress report was 

published in 2008, we have separated the results by year and by production technology. 

With 5 years of data now analyzed, we can see that the hydrogen quality index of 99.97% 

has been achieved in all the quality samples for the last 3 years and does not seem to be 

an issue. 

• Hydrogen Impurities: More important than the absolute hydrogen fuel quality index is the 

actual level of impurities by constituent. Impurities evaluated include particulates, inert 

gases (N2 + H2 + Ar), NH3, CO, CO2, O2, total HC, H2O, and total S, and are shown in

Figure 70. Subsequent to the last progress report, each of these constituents was broken 

out separately and shown as a function of year. There are 18 of these results (Figure 71

to Figure 88), so we will not discuss each one individually except to say that the detection 

limits continue to improve (get lower) through better gas analysis techniques, and there 

do not appear to be any major issues with any of the impurities. Impurity data from this 

project has been used by the hydrogen quality community on numerous occasions to 

answer the question of what is possible and what are the actual impurities found in 

hydrogen fuel made by various techniques. 

• H2 Infrastructure Maintenance: An evaluation of all of the maintenance required on 

refueling station equipment found that roughly one-half of all labor hours were 

unscheduled, accounting for 60% of the maintenance events (Figure 89). With the large 

volume of infrastructure maintenance items over the past five years, we have not seen 

any shift in the split planned and unplanned maintenance events. Similar to the FCEV

maintenance, we have now classified the parts of the fueling station systems that caused 

the maintenance events (Figure 90). The left pie shows the number of events (2,491 

events) separated by subsystem while the right pie shows the number of labor hours 

(11,430 hours). The main conclusion from this result is that “system control & safety”

required both the most time to fix as well as were the most frequent system requiring 

maintenance. The rest of the maintenance was spread relatively evenly between the 

compressor, reformer, electrolyzer, and dispenser.
24

• Infrastructure Safety: With respect to the hydrogen refueling infrastructure, there have

been just a handful of events classified as incidents, according to DOE’s Safety Panel 

definition. Most of these were due to equipment malfunction with one event having a 

minor hydrogen release that did not lead to ignition and another one involving a major 

hydrogen release and a fire. Details of this event are available from DOE’s Safety Panel. 

At a less severe level (see Figure 91), there were about 50 events categorized as nearmisses and around 275 non-events (over 100 were alarms-only and about 70 were 

“system trouble, not alarm”). All but a handful of the near-misses involved a minor 

release of hydrogen with no ignition. 

Figure 92 shows that no single primary factor led to the majority of infrastructure safety 

reports, but the top three most frequent primary factors for the non-events were 1) 

calibrations, settings, and software controls; 2) maintenance required; and 3) not yet 

determined (in other words insufficient information was provided to NREL for us to 

make a determination how to categorize some of the events). 

Figure 93 shows that the number of refuelings normalized by the number of safety reports 

per quarter had improved by a factor of 10 (higher is better) since the beginning of the 

project, but then dipped down to 60-80 as new stations came online. It has since gone 

higher, staying above 100 for the last year. Figure 94 shows the apparent correlation 

between new stations coming online and a higher number of safety reports. On most of 

the safety CDPs we have now added the DOE definition of incident and near-miss that 

are being used for this project to remove any questions about what they mean since they 

are not necessarily obvious to the layman.

• Vehicle Fueling Rates: Hydrogen vehicle refueling needs to be as similar as possible to 

conventional vehicle refueling to allow an easier commercial market introduction. Over 

25,000 refueling events have been analyzed to date, and the refueling amount, time, and 

rate have been quantified. The average time to refuel was 3.26 minutes with 86% of the 

refueling events taking less than 5 minutes (Figure 95). The average amount per fill was 

2.13 kg, reflecting both the limited storage capacity of these vehicles (approximately 4 kg 

maximum) and peoples’ comfort level with letting the fuel gauge get close to empty (see 

Figure 96 for the shape of the distributions), which will be shown in a separate analysis. 

DOE’s initial target refueling rate is 1 kg/minute, and these Learning Demonstration

results indicate an average of 0.77 kg/min, with 23% of the refueling events exceeding 1 

kg/minute (Figure 97). Therefore, we can conclude that high-pressure gases are 

approaching adequate refueling times and rates for consumers; however, the challenge is 

still in packaging enough high-pressure hydrogen onboard to provide adequate range or 

finding alternate advanced hydrogen storage materials that can replace the need for highpressure tanks.

• Communication vs. Non-Communication Fueling Rates: The previous refueling 

histograms included all types of refueling events. There has been much interest from 

industry and from the codes and standards community about the potential for 

communication fills to occur at a higher rate and with a more complete fill. A 

communication fill means that the vehicle communicates data about the state of its 

hydrogen storage tank(s) to the refueling station, such as tank temperature, pressure, and 

max pressure rating. Figure 98 shows two curves: the red curve is a spline fit to the 

histogram for non-communication fills while the blue curve represents the 
25

communication fills. The center part of the graph shows a similar rate of fill for the 

communication and non-communication fills; however, the communication fills are 

capable of having a higher fill rate (up to around 1.8 kg/min). There is also a group of 

vehicle/station combinations still doing non-communication fills at the slower rate of 

~0.2 kg/min on the left portion of the graph. This rate of fill was established many years 

ago in California to provide a conservative and safe approach for refueling vehicles 

before much real-world experience had been gained. With these differences in 

distribution in mind, the average fill rate for all communication fills is 0.86 kg/min vs. 

0.66 kg/min for non-communication fills, with 30% and 12%, respectively, exceeding 

DOE’s 1 kg/min target. We can thus conclude that communication fills in this project 

are, on average, faster than non-communication fills.

• Fueling Rate by Storage System (350 bar vs. 700 bar): Another partition of the fueling 

rate data we performed was by the storage system employed by each vehicle. Figure 99

shows the fueling rate for 350 bar fills and compares them to the fueling rate for 700 bar 

fills. Two major conclusions can be drawn from this graph. The first is that the project 

has experienced many more 350-bar fills (19,659) than 700-bar fills (5,590), since the 

700-bar fuelings mainly began with the second-generation vehicles halfway through the 

project. The second is that the fueling rate for the higher pressure fills is still slower than 

the lower pressure fills, with 29% of the 350-bar fills exceeding 1 kg/min and only 4% of 

the 700-bar fills exceeding the target. The average fill rate for 350-bar fills is 0.82 

kg/min, while the average rate for 700-bar fills is 0.63. This does not appear to be a 

limitation of the technology, as very high fill rates at 700 bar have been demonstrated in 

Germany and Canada, but rather a reflection of the current technology that has been 

deployed in this first wave of 700-bar stations. Station data received in the coming years 

from the new stations in California should demonstrate the full capability of 700-bar 

fueling. 

• Fueling Rate by Year: In the final fueling rate analysis, we have sliced the same data by 

year (Figure 100). We can see that the number of fueling events has increased year-toyear during each of the 5 years of the project to date. While the fueling rate initially 

increased from 0.66 to 0.74 kg/min to 0.81 kg/min, it has now settled at a value of 0.77 

kg/min for the last two years. Due to the number of automotive companies being reduced 

from four to two in 2010, the overall number of fueling events will decrease until the new 

California stations come online.

• Level in Fuel Tank When People Refuel: As previously mentioned, with limited hydrogen 

refueling infrastructure and limited on-board hydrogen storage, some drivers do not like 

to let the tank get close to empty to minimize the risk of running out of fuel. To 

investigate this further, NREL used the data submitted in a new and unique way, which 

was to look at what the fuel level in the tank was just prior to each refueling event. In 

some cases these data came from on-board data based on the pressure in the tank, and in 

other cases they came from refueling logs where each fill was assumed to be to the “full” 

level, allowing a subtraction of the amount fueled to determine the initial tank level. 

Figure 101 shows the results of this analysis, where a histogram has been placed radially 

on an image of a fuel gauge to make interpreting the graph as intuitive as possible. The 

level at which people most commonly refuel the Learning Demonstration vehicles is at 

just over one-quarter full; this covers 14% of the refuelings. While some drivers are 
26

letting the tank get even lower than that, few let it get close to being empty. Additionally, 

we have placed a green needle on the chart that indicates the median tank level at fill 

(half above, half below), which is a little above three-eighths of a tank (42% of full). 

Figure 102 shows the collection of medians for each of the 144 vehicles in the Learning 

Demonstration fleet to show that there is a large spread in when individuals choose to 

refuel their vehicles, with several vehicles being refueled more than half of the time with 

greater than a half-full tank, but the majority being refueled between one-quarter and onehalf full, on average. In the future, we would like to compare these data results to data 

from conventional liquid-fueled vehicles, if they exist, to see if people are refueling their 

FCEVs differently than their conventional vehicles.

• Time of Day When People Fuel Their FCEVs: We examined the time of day people 

fueled their vehicles in order to understand the usage patterns at the hydrogen fueling 

stations and to better allow new stations to understand the potential demand by time of 

day. For traditional liquid fuels, with big tanker truck deliveries periodically, the time of 

day people refuel does not normally matter. Instead, the station operator must simply 

ensure that the next tanker comes before he runs out of fuel. For today’s hydrogen fuel

stations, with very limited storage capacity and some sites producing hydrogen 

throughout the day, it is important to know the time of day that people refuel in order to 

match the supply (onsite production) with the demand. 

Figure 103 shows a radial histogram of the time of day Learning Demonstration vehicles 

were refueled between 6 a.m. and 6 p.m., with Figure 104 showing the time between 6 

p.m. and 6 a.m. We found that 90% of the fills took place between 6 a.m. and 6 p.m., 

with 10% being done at night. The distribution is relatively uniform with steady usage 

between 8 a.m. and 4 p.m., and a mild peak just after lunchtime (9%). The conclusion 

from this analysis is that with a uniform distribution of when people refuel during the 

day, a station that has on-site production can either be sized to meet that demand during 

the day and then essentially shut off at night, or it can be sized (smaller) for the average 

over a 24-hour period, have a larger on-site hydrogen storage buffer, and run 

continuously. Finally, we looked at what day of the week people were refueling (Figure 

105) and found that the Learning Demonstration vehicles are almost exclusively fueled 

Monday through Friday, with very few vehicles fueled on the weekend. This is 

consistent with the days of the week that people are driving the vehicles most and when 

the hydrogen stations that have attendants are open.

• Other Infrastructure Metrics: The cumulative amount of hydrogen produced or dispensed 

has also been tracked by quarter (blue triangles) with the number of stations shown on the 

same graph (green squares) in Figure 106. Note that the amount of hydrogen produced is 

not the same as the amount dispensed because the project includes a power park where

the unused hydrogen can be converted back into grid electricity during peak utility load 

periods in the afternoon (due to higher air-conditioning loads) using on-site fuel cells.
27

2.3 Conclusions and Future Directions

NREL has now completed the first five years of the seven-year project with 144 vehicles 

deployed in fleet operation, 23 project refueling stations constructed, and no major safety 

barriers encountered. We have analyzed data from 436,000 individual vehicle trips covering 2.5 

million miles traveled and 130,000 kg hydrogen produced or dispensed. We have published 80 

technical CDPs to date and made them directly accessible to the public from an NREL Web site. 

We have summarized the key project performance numbers, along with other metrics of interest 

such as fuel economy and fuel cell efficiency, and compared them to DOE targets in Table 1. 

The table shows that this project has exceeded the expectations established in 2003 by DOE, 

with all of the key targets being achieved except for onsite hydrogen production cost, which 

would have been difficult to demonstrate through this project. 

From all of the results that we have generated, it is our conclusion that FCEVs have advanced 

rapidly in the last five years, and are expected to continue at this same rate of development in the 

next five years. There do not appear to be any major technical hurdles that the automotive 

companies and their suppliers cannot overcome, and they appear to have a glide-path to getting 

the costs down to a manageable incremental cost. We therefore expect continued progress to 

lead to market-ready vehicles in the 2015 timeframe. Several vehicle manufacturers will 

introduce thousands of vehicles to the market in that timeframe, and the hydrogen community 

will have its first true test of whether the technology will be embraced by the public. 

Additional data accumulated and analyzed in 2010–2012 will assess the latest generations of 

FCEV technology, which include improvements over the second-generation systems included in 

the results to date. NREL will create new and updated CDPs based on data collected through 

June 2010 (Fall 2010 CDPs) and present results for publication at 2010 Fuel Cell Seminar. We 

will support the automotive manufacturers, energy companies, and state organizations in 

California in coordinating early infrastructure plans. We will gather and analyze data from a 

hydrogen fueling station in Burbank, California, which has a relatively high-rate of onsite 

production from natural gas, along with many new stations that are being opened in California in 

the next year. NREL will continue to identify opportunities to feed findings from the project 

back into Vehicle Technologies and Fuel Cell Technologies programs and industry R&D 

activities to maintain the project as a “learning demonstration.” We will continue to gather data 

from FCEVs and hydrogen stations through 2011, and publish the Spring 2011 and Fall 2011 

CDPs and potentially one final set of results in Spring 2012. As the last expected deliverable 

from this project, we will write a final summary report for publication, which will both include 

new results from the final two years as well as reference and build on the results included in this 

report.

Future assessments will also include data analysis from many new hydrogen stations being 

commissioned in California, all of which will have 700-bar fueling capability. All 80 CDPs

published to date are included in this report as well as directly accessible from our Hydrogen 

Technology Validation Web site.
28

2.4 Recent Publications/Presentations

1. Wipke, K., Anton, D., and Sprik, S., “Evaluation of Range Estimates for Toyota FCHV-adv Under 

Open Road Driving Conditions,” prepared under SRNS CRADA number CR-04-003, August 2009. 

(paper)

2. Wipke, K., Sprik, S., Kurtz, J., and Ramsden, T., “Fall 2009 Composite Data Products for the 

Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” Golden, CO: 

National Renewable Energy Laboratory, September 2009. (presentation) 

3. Wipke, K., Sprik, S., Kurtz, J., Ramsden, T., and Garbak, J., “National Fuel Cell Vehicle Learning 

Demonstration: Gen 2 Progress,” presented at the California Air Resources Board 2009 ZEV 

Technology Symposium, Sacramento, CA, September 2009. (presentation)

4. Wipke, K, Sprik, S., and Kurtz, J., 2009 Annual Progress Report for NREL’s “Controlled Hydrogen 

Fleet and Infrastructure Analysis Project,” Section VIII.1, November 2009. (paper).

5. Wipke, K., Sprik, S., Kurtz, J., Ramsden, T., and Garbak, J., “Second-Generation Fuel Cell Stack 

Durability and Freeze Capability from National FCEV Learning Demonstration,” 2009 Fuel Cell 

Seminar & Exposition, Palm Springs, CA, November, 2009. (presentation)

6. Kurtz, J., Wipke, K., Sprik, S., and Ramsden, T., “Analysis of Real World Fuel Cell Degradation,” 

Fuel Cells Durability & Performance Conference, Alexandria, VA, December 2009. (presentation)

7. Wipke, K., Sprik, S., Kurtz, J., Ramsden, T., and Garbak, J., “U.S. Fuel Cell Vehicle Learning 

Demonstration: Status Update and Early Second-Generation Vehicle Results,” World Electric Vehicle 

Association Journal, Vol. 3 – ISSN 2032-6653, December 2009. (paper)

8. Wipke, K., Sprik, S., Kurtz, J., and Ramsden, T., “Spring 2010 Composite Data Products for the 

Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” Golden, CO: 

National Renewable Energy Laboratory, March 2010. (presentation) 

9. Wipke, K., Sprik, S., Kurtz, J., Ramsden, T., and Garbak, J., “Status and Results from National Fuel 

Cell Vehicle Learning Demonstration,” General Motors Lunch and Learn Presentation, Honeoye 

Falls, NY, April 2010. (presentation) 

10. Wipke, K., Sprik, S., Kurtz, J., and Ramsden, T., presentation of Learning Demonstration results to 

FreedomCAR and Fuels joint meeting of the Fuel Cell and Hydrogen Storage Tech Team, April 2010. 

(presentation)

11. Wipke, K., Sprik, S., Kurtz, J., Ramsden, T., and Garbak, J., “Exceeding Expectations: Learnings 

from FCEV Learning Demo,” National Hydrogen Association Annual Hydrogen Conference, Long 

Beach, CA, May 2010. (presentation) 

12. Wipke, K., Sprik, S., Kurtz, J., and Ramsden, T., “Session TA.5 - Demonstration Projects, Costs, and 

Market Introduction: Review Lecture,” 2010 World Hydrogen Energy Conference (WHEC) in Messe 

Essen, Germany, May 2010. (presentation) 

13. Wipke, K., Sprik, S., Kurtz, T., and Ramsden, T., “Controlled Hydrogen Fleet and Infrastructure 

Analysis,” 2010 U.S. DOE Hydrogen Program and Vehicle Technologies Program Annual Merit 

Review and Peer Evaluation Meeting, Washington, D.C, June 2010. (presentation) 

14. Wipke, K., Sprik, S., Kurtz, J., Ramsden, T., and Garbak, J., “DOE’s National Fuel Cell Vehicle 

Learning Demonstration Project – NREL’s Data Analysis Results,” Electric and Hybrid Vehicles, 

Power Sources, Models, Sustainability, Infrastructure and the Market, Chapter 12, ISBN 978-0-444-

53565-8, NREL/CH-560-47111, Elsevier B.V., August 2010.
29

2.5 References

1. Wipke, K., Sprik, S., Thomas, H., Welch, C., Kurtz, J., “Learning Demonstration Interim Progress 

Report - Summer 2007,” NREL/TP-560-41848, June 2007.

2. Wipke, K., Sprik, S., Kurtz, J., Thomas, H., “Learning Demonstration Progress Report—September 

2007,” NREL/TP-560-42264, November 2007.

3. Wipke, K., Sprik, S., Kurtz, J., “Learning Demonstration Progress Report—Spring 2008,” NREL/TP560-42986, April 2008. 

4. Wipke, K., Anton, D., and Sprik, S., “Evaluation of Range Estimates for Toyota FCHV-adv Under 

Open Road Driving Conditions,” prepared under SRNS CRADA number CR-04-003, August 2009.

5. Fletcher, J., and Callaghan, V., “Evaluation Cost of Distributed Production of Hydrogen from Natural 

Gas – Independent Review,” NREL/BK-150-40382, October 2006.

6. Genovese, J., Harg, K., Paster, M., and Turner, J., “Current (2009) State-of-the-Art Hydrogen 

Production Cost Estimate Using Water Electrolysis – Independent Review,” NREL/BK-6A1-46676, 

September 2009. 
30 

2.6 Composite Data Products Referenced in Previous Discussion 

Figure 12: Fuel cell system efficiency (CDP08) 

Figure 13: Fuel cell system operating power (CDP46) 

0 10 20 30 40 50 60 70 80 90 100 0

10

20

30

40

50

60

Net System Power [%]

Efficiency [%]

Fuel Cell System1 Efficiency2

 Eff. at 25% Pwr Eff. at 100% Pwr

 ------------------- -------------------

Gen1 51 - 58% 30 - 54%

Gen2 53 - 59% 42 - 53%

DOE Target at 25% Power

DOE Target at 100% Power

Gen 1 Efficiency Range

Gen 2 Efficiency Range

NREL CDP08

Created: Sep-02-09 11:27 AM

1

 Gross stack power minus fuel cell system auxiliaries, per DRAFT SAE J2615. Excludes power electronics and electric drive.

2

 Ratio of DC output energy to the lower heating value of the input fuel (hydrogen). 

3

 Individual test data linearly interpolated at 5,10,15,25,50,75,and 100% of max net power. Values at high power linearly extrapolated 

 due to steady state dynamometer cooling limitations.

0

10

20

30

40

50

Time at Fuel Cell Stack Power Levels: DOE Fleet

Operating Time [%]

0-5%

5-10%

10-15%

15-20%

20-25%

25-30%

30-35%

35-40%

40-45%

45-50%

50-55%

55-60%

60-65%

65-70%

70-75%

75-80%

80-85%

85-90%

90-95%

95-100%

>100%

% Max Fuel Cell Power (Gross)

All time

Time with 0 speed

NREL CDP46

Created: Mar-09-10 4:21 PM
31 

Figure 14: Fuel cell system energy within power levels (CDP53) 

Figure 15: Trip length (CDP47) 

0

2

4

6

8

10

FC Energy by Power Levels: DOE Fleet

FC Energy [%]

0-5%

5-10%

10-15%

15-20%

20-25%

25-30%

30-35%

35-40%

40-45%

45-50%

50-55%

55-60%

60-65%

65-70%

70-75%

75-80%

80-85%

85-90%

90-95%

95-100%

>100%

% Fuel Cell Power (Gross) of Max

Cumulative %

0

20

40

60

80

100

NREL CDP53

Created: Mar-11-10 9:13 AM

0 5 10 15 20 25 0

5

10

15

20

25

30

35

40

45

Trip Frequency [%]

Trip Length [miles]

Trip Length: DOE Fleet

DOE Fleet

NHTS

NREL CDP47

Created: Mar-09-10 4:16 PM

2001 NHTS Data Includes Car, Truck, Van, & SUV day trips

ASCII.csv Source: http://nhts.ornl.gov/download.shtml#2001
32 

Figure 16: Fuel cell electric vehicle with comparison to standard drive cycles (CDP66) 

Figure 17: Percent idle in trip with comparison to standard drive cycles (CDP65) 

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 0

5

10

15

20

25

30

35

40

Speed [mph]

Operation Time [%]

Fuel Cell Vehicle Speed

DOE Fleet Speed

DOE Fleet Idle

1015 Cycle (14.1 mph avg)

UDDS Cycle (19.6 mph avg)

HWFET Cycle (48.0 mph avg)

US06 Cycle (48.2 mph avg)

NREL CDP66

Created: Mar-09-10 4:17 PM

0

2

4

6

8

10

12

14

HWFET CycleUS06 CycleUDDS Cycle1015 Cycle

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Percent Idle in Trip

% Idle

Trip Frequency [%]

NREL CDP65

Created: Mar-09-10 4:17 PM
33 

Figure 18: Fuel cell system energy in trips (CDP55) 

Figure 19: Daily driving distance (CDP56) 

<-0.5 -0.5-0 0-0.5 0.5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5 3.5-4 4-4.5 4.5-5 >5 0

10

20

30

40

50

60

Energy Consumed [kWh]

Trip Frequency [%]

Energy in Trip: DOE Fleet

Net battery

charge in trip

Battery

Vehicle Motor

FC

NREL CDP55

Created: Mar-09-10 4:16 PM

0 5 10 15 20 25 30 35 40 0

2

4

6

8

10

12

14

16

18

20

Trip Frequency [%]

Daily Distance [miles]

Daily Distance: DOE Fleet

DOE Fleet

NHTS

NREL CDP56

Created: Mar-09-10 4:17 PM

Cumulative Frequency

@ 20 miles

DOE Fleet: 47.4%

NHTS: 27.2%

Cumulative Frequency

@ 40 miles

DOE Fleet: 67.2%

NHTS: 52.9%

2001 NHTS Data Includes Car, Truck, Van, & SUV day trips

ASCII.csv Source: http://nhts.ornl.gov/download.shtml#2001
34 

Figure 20: Time between trips (CDP54) 

Figure 21: Fuel economy (CDP06) 

0-1 hr 1-6 hr 6-12 hr 12-18hr 18-24hr 1-7days 7-30days >30days 0

10

20

30

40

50

60

Trip Frequency [%]

Time

Time between Trips: DOE Fleet

0-10 min 10-20 min 20-30 min 30-40 min 40-50 min 50-60 min 0

10

20

30

40

50

% Trips

Time

0-60 min Breakdown: DOE Fleet

NREL CDP54

Created: Mar-09-10 4:16 PM

Dyno (1) Window-Sticker (2) On-Road (3)(4) 0

10

20

30

40

50

60

70

80

Fuel Economy (miles/kg H2

)

Fuel Economy

 Gen 1

 Gen 2

NREL CDP06

Created: Mar-10-10 1:18 PM

(1) One data point for each make/model. Combined City/Hwy fuel economy per DRAFT SAE J2572.

(2) Adjusted combined City/Hwy fuel economy (0.78 x Hwy, 0.9 x City).

(3) Excludes trips < 1 mile. One data point for on-road fleet average of each make/model.

(4) Calculated from on-road fuel cell stack current or mass flow readings.
35 

Figure 22: Vehicle driving range (CDP02) 

Figure 23: Miles between refuelings (CDP80) 

Dyno Range (2) Window-Sticker Range (3) On-Road Range (4)(5) 0

50

100

150

200

250

300

Vehicle Range (miles)

Vehicle Range1

2015 Target

2009 Target

 Gen 1

 Gen 2

NREL CDP02

Created: Mar-10-10 1:18 PM

(1) Range is based on fuel economy and usable hydrogen on-board the vehicle. One data point for each make/model.

(2) Fuel economy from unadjusted combined City/Hwy per DRAFT SAE J2572.

(3) Fuel economy from EPA Adjusted combined City/Hwy (0.78 x Hwy, 0.9 x City).

(4) Excludes trips < 1 mile. One data point for on-road fleet average of each make/model.

(5) Fuel economy calculated from on-road fuel cell stack current or mass flow readings.

0 50 100 150 200 250 300 0

5

10

Percentage of Refuelings

Distance between refuelings [Miles]2

Distance Driven Between Refuelings: All OEMs

Gen1

Gen2

NREL CDP80

Created: Mar-23-10 10:53 AM

Total Refuelings1 = 25811

 Gen1

 Refuelings = 18941

 Median distance between refuelings = 56 Miles

 Gen2

 Refuelings = 6870

 Median distance between refuelings = 81 Miles

1. Some refueling events are not detected/reported due to data noise or incompleteness.

2. Distance driven between refuelings is indicative of driver behavior and does not represent the full range of the vehicle.
36 

Figure 24: Percentage of theoretical range traveled between refuelings (CDP33) 

Figure 25: Effective vehicle driving range (CDP34) 

0 10 20 30 40 50 60 70 80 90 100 0

1

2

3

4

5

6

7

8

9

10

11

12

13

Range Histogram: All OEMs

Percentage of chassis dyno range1

 between refuelings

Percentage of Refuelings

0 10 20 30 40 50 60 70 80 90 1000

25

50

75

100

Cumulative Percentage

NREL CDP33

Created: Mar-23-10 10:53 AM

Total refuelings2 = 25811

1. Range calculated using the combined City/Hwy fuel economy from dyno testing (not EPA

adjusted) and usable fuel on board.

2. Some refueling events are not detected/reported due to data noise or incompleteness.

0 10 20 30 40 50 60 70 80 90 100

Gen1

Gen2

Vehicle Range Factors

Percentage of chassis dyno range1

.

All OEMs

Window-Sticker 2 Window-Sticker 2

On-Road 3 On-Road 3

Dyno 1

NREL CDP34

Created: Mar-10-10 1:25 PM

1. Calculated using the combined City/Hwy fuel economy from dyno testing (non-adjusted)

and usable fuel on board.

2. Applying window-sticker correction factors for fuel economy: 0.78 x Hwy and 0.9 x City.

3. Using fuel economy from on-road data (excluding trips < 1 mile, consistent with other data products).
37 

Figure 26: Storage weight % hydrogen (CDP10) 

Figure 27: Volumetric capacity of hydrogen storage (CDP11) 

350bar 700bar 0

1

2

3

4

5

6

7

8

9

Weight Percent Hydrogen (%)

Weight Percent Hydrogen

2015 DOE MYPP Target1

2010 DOE MYPP Target1

2007 DOE MYPP Target1

NREL CDP10

Created: Aug-19-08 11:39 AM

1

Targets are set for advanced materials-based hydrogen storage technologies.

350bar 700bar 0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Mass H2 per Liter (kg/L)

Mass of Hydrogen Per Liter

2015 DOE MYPP Target1

2010 DOE MYPP Target1

2007 DOE MYPP Target1

NREL CDP11

Created: Aug-19-08 11:39 AM

1

Targets are set for advanced materials-based hydrogen storage technologies.
38 

Figure 28: Hydrogen storage system mass and volume breakdown (CDP57) 

Figure 29: Vehicle hydrogen tank cycle life (CDP12) 

73%

24%

3%

Average Breakout of H2 Storage System Volume

3.26%

73%

23%

Average Breakout of H2 Storage System Mass

35% 56%

9%

H2 Volume (%)

Pressure Vessel Volume (%)

Balance of Plant Volume (%)

3.33%

72%

24%

H2 Mass (%)

Pressure Vessel Mass (%)

Created: Aug-19-08 9:14 AM Balance of Plant Mass (%)

350 bar

700 bar

NREL CDP57

0 

2000 

4000 

6000 

8000 

10000

12000

14000

16000

18000

Number of cycles

Hydrogen Tank Cycle Life1

All OEMs

2015 DOE MYPP Target2

2010 DOE MYPP Target2

2007 DOE MYPP Target2

 Gen 1

 Gen 2

NREL CDP12

Created: Sep-17-08 10:29 AM

1

Data reported reference NGV2, HGV2, or EIHP standards.

2

Some near-term targets have been achieved with compressed and liquid tanks. Emphasis is on advanced materials-based technologies.
39 

Figure 30: Fuel cell system specific power (CDP59) 

Figure 31: Fuel cell system power density (CDP58) 

0

100

200

300

400

500

600

700

Specific Power (W/kg)

FC System Specific Power (W/kg)

2010 and 2015 DOE MYPP Target1 Gen 1

 Gen 2

NREL CDP59

Created: Sep-17-08 10:30 AM (1) Fuel cell system includes fuel cell stack and BOP but excludes H2 storage, power electronics, and electric drive.

0

100

200

300

400

500

600

700

Power Density (W/L)

FC System Power Density (W/L)

2010 and 2015 DOE MYPP Target1 Gen 1

 Gen 2

NREL CDP58

Created: Sep-17-08 10:29 AM (1) Fuel cell system includes fuel cell stack and BOP but excludes H2 storage, power electronics, and electric drive.
40 

Figure 32: Fuel cell system specific power, including hydrogen storage (CDP04) 

Figure 33: Fuel cell system power density, including hydrogen storage (CDP03) 

0

50

100

150

200

250

300

350

400

Specific Power (W/kg)

FC System (Including Hydrogen Storage) Specific Power (W/kg)

2010 and 2015 FreedomCAR Research Goal1

 Gen 1

 Gen 2

NREL CDP04

Created: Aug-28-09 8:42 AM (1) Fuel cell system includes fuel cell stack, BOP and H2 storage, but excludes power electronics, battery storage, and electric drive.

0

50

100

150

200

250

300

350

400

Power Density (W/L)

FC System (Including Hydrogen Storage) Power Density (W/L)

2010 and 2015 FreedomCAR Research Goal1

 Gen 1

 Gen 2

NREL CDP03

Created: Sep-08-09 10:32 AM (1) Fuel cell system includes fuel cell stack, BOP and H2 storage, but excludes power electronics, battery storage, and electric drive.
41 

Figure 34: Hours accumulated and projected hours to 10% stack voltage degradation 

(CDP01) 

Figure 35: Maximum fuel cell power degradation—Gen 1 (CDP69) 

Gen1 Gen2 Gen1 Gen2 Gen1 Gen2 0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

2800

2006 Target

2009 Target

Actual Operating Hours Accumulated To-Date Projected Hours to 10% Voltage Degradation

Time (Hours)

DOE Learning Demonstration Fuel Cell Stack Durability:

Based on Data Through 2009 Q2

Max Hrs Accumulated1,2 Avg Hrs Accumulated1,3 Projection to 10% Voltage Degradation4,5,6

Max Projection

Avg Projection

NREL CDP01

Created: Mar-23-10 10:39 AM

(1) Range bars created using one data point for each OEM. Some stacks have accumulated hours beyond 10% voltage degradation.

(2) Range (highest and lowest) of the maximum operating hours accumulated to-date of any OEM's individual stack in "real-world" operation.

(3) Range (highest and lowest) of the average operating hours accumulated to-date of all stacks in each OEM's fleet.

(4) Projection using on-road data -- degradation calculated at high stack current. This criterion is used for assessing progress against DOE targets,

 may differ from OEM's end-of-life criterion, and does not address "catastrophic" failure modes, such as membrane failure.

(5) Using one nominal projection per OEM: "Max Projection" = highest nominal projection, "Avg Projection" = average nominal projection.

 The shaded projection bars represents an engineering judgment of the uncertainty on the "Avg Projection" due to data and methodology limitations. 

 Projections will change as additional data are accumulated.

(6) Projection method was modified beginning with 2009 Q2 data, includes an upper projection limit based on demonstrated op hours.

30

40

50

60

70

80

90

100

110

120

130

 0 100 200 300 400 500 600 700 800 900 10001100120013001400150016001700180019002000

Stack Op Hour Segments(2)

% Power(1)

Max Fuel Cell Power Loss vs Op Hours: Gen1

1) Normalized by fleet median value at 200 hours.

2) Each segment point is median FC power (+-50 hrs).

 Box not drawn if fewer than 3 points in segment.

Gen1 Data Range

25th & 75th Percentiles

Group Median

Outlier

NREL CDP69

Created: Mar-23-10 10:39 AM
42 

Figure 36: Maximum fuel cell power degradation—Gen 2 (CDP70) 

Figure 37: Fuel cell stack projected hours as a function of voltage drop (CDP73) 

30

40

50

60

70

80

90

100

110

120

130

 0 100 200 300 400 500 600 700 800 900 10001100120013001400150016001700180019002000

Stack Op Hour Segments(2)

% Power(1)

Max Fuel Cell Power Loss vs Op Hours: Gen2

1) Normalized by fleet median value at 200 hours.

2) Each segment point is median FC power (+-50 hrs).

 Box not drawn if fewer than 3 points in segment.

Gen2 Data Range

25th & 75th Percentiles

Group Median

Outlier

NREL CDP70

Created: Mar-23-10 10:39 AM

10 15 20 25 30 0

200

400

600

800

1000

1200

1400

1600

1800

2000

Fuel Cell Stack Projected Hours as a Function of Voltage Drop

% Voltage Drop

Projected Hours2,3

Gen 1 Average Projections

Gen 1 Average Projection to 10% Voltage Degradation1

Gen 2 Average Projections

Gen 2 Average Projection to 10% Voltage Degradation1

NREL CDP73

Created: Mar-23-10 10:40 AM

(1) 10% Voltage degradation is a DOE metric for assessing fuel cell performance.

(2) Projections using on-road data -- degradation calculated at high stack current.

(3) Curves generated using the Learning Demonstration average of each individual fleet average at various voltage degradation levels.

(4) The projection curves display the sensitivity to percentage of voltage degradation,

 but the projections do not imply that all stacks will (or do) operate at these voltage degradation levels.

(5) The voltage degradation levels are not an indication of an OEM's end-of-life criteria and do not address catastrophic stack

 failures such as membrane failure.

(6) All OEM Gen 2 average fleet projections are higher than Gen1 projections, however due to less operation data for Gen 2,

 these projections are limited by demonstrated operation hours to minimize extrapolations.
43 

Figure 38: Power drop during fuel cell stack operating period (CDP68) 

Figure 39: Projected hours to OEM low power operation limit (CDP71) 

0 5 10 15 20 25 30 35 40 0

5

10

15

20

25

30

Stack Count

% FC Power Drop

FC Power Drop During Operation Period: Gen1

Gen1

60% of In Op stacks

have > 10% power drop

In Op1

Retired2

Other3

0 5 10 15 20 25 30 35 40 0

5

10

15

20

25

30

Stack Count

% FC Power Drop

FC Power Drop During Operation Period: Gen2

Gen2

85% of In Op stacks

have > 10% power drop

In Op1

Retired2

Other3

NREL CDP68

Created: Mar-23-10 10:39 AM

1) Stack currently accumulating hours

2) Stack removed for low performance

3) Stack not currently accumulating hours, but not removed because of low performance.

 Some project teams concluded in Fall/Winter 2009

0-200 400 600 800 1000 1200 1400 1600 1800 2000 >2000 0

5

10

15

20

25

30

27% Gen1 > 2000 projected hrs

17% Gen2 > 2000 projected hrs

Projected Hours

% Stacks

Durability: Projected Hours to Low Fuel Cell Power Limit

Gen1 (> 200 operation hrs)

Gen1 (< 200 operation hrs)

Gen2 (> 200 operation hrs)

Gen2 (< 200 operation hrs)

NREL CDP71

Created: Mar-23-10 10:39 AM

1. Low fuel cell power limit is dependent on the fuel cell vehicle system and is unique to each company in this Learning Demonstration.

2. Acceptable low vehicle performance limit will be determined by retail customer expectations.

3. Power projection method based on the voltage degradation techniques, but uses max fuel cell power instead of voltage at a specific

high current.

4. Stacks with less than 200 operation hours are in separate groups because the projection is based on operation data and with operation

hours greater than 200 the degradation rate tends to flatten out.
44 

Figure 40: Fuel cell stack operation hours (CDP67) 

Figure 41: Fuel cell stack trips per hour histogram (CDP16) 

0

5

10

15

20

25

30

35

40

Stack Count

Fuel Cell Stack Operation Hours: Gen1

Gen1

0 

200

400 

600 

800

1000

1200

1400

1600

1800

2000

Gen1 Hours

24% of stacks in operation

In Op1

Retired2

Other3

0

5

10

15

20

25

30

35

40

Stack Count

Fuel Cell Stack Operation Hours: Gen2

Gen2

0 

200 

400

600

800

1000

1200

1400

1600

1800

2000

Gen2 Hours

34% of stacks in operation

In Op1

Retired2

Other3

NREL CDP67

Created: Mar-23-10 10:39 AM

1) Stack currently accumulating hours

2) Stack removed for low performance

3) Stack not currently accumulating hours, but not removed because of low performance.

 Some project teams concluded in Fall/Winter 2009

0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 >8 0

5

10

15

20

25

30

Segmented Trips/Hour Histogram: DOE Fleet

Trips/Hour*

Frequency [%]

*Trips/Hour based on 50 hour segments

spanning stack operating period

NREL CDP16

Created: Mar-09-10 4:13 PM
45 

Figure 42: Statistics of trips/hour vs. operating hour (CDP17) 

Figure 43: Primary factors affecting learning demonstration fleet fuel cell degradation 

(CDP48) 

0

1

2

3

4

5

6

7

8

9

10

0-250 250-500 500-750 750-1000 1000-1250 1250-1500 1500-1750 1750-2000

Stack Op Hour Groups

Trips/Hour*

Statistics of Trips/Hour vs Operating Hour: DOE Fleet

*Trips/Hour based on 50 hour segments

spanning stack operating period

Data Range

25th & 75th Percentiles

Group Median

Outlier

NREL CDP17

Created: Mar-09-10 4:13 PM

DOE Fleet

High Current Time

Hot Starts

Starts/hour

Low Voltage Time

High Voltage Time

Cold Starts

Short Trips

0 Speed Trips

Hot Ambient Temp

H*

H*

1) On-going fuel cell degradation study using Partial Least Squares (PLS) 

regression model for combined Learning Demonstration Fleet.

2) DOE Fleet model has a low percentage of explained decay rate variance. 

Created: Feb-21-08 9:32 AM

H*: Factor group associated with high decay rate fuel cell stacks

L**: Factor group associated with low decay rate fuel cell stacks

Due to differences among teams, the 

DOE Fleet Analysis results are spread 

out and concrete conclusions are difficult 

to draw.

Individual team analyses (CDP#49) 

focused on patterns within a fleet.

NREL CDP48
46 

Figure 44: Primary factors affecting learning demonstration team fuel cell degradation 

(CDP49) 

Figure 45: Fuel cell voltage (CDP07) 

Team 1

High Voltage Time

Low Current Time

Short Trips

Low Speed

Team 2

Team 3

Team 4

Low Current Time

Long Trips

Warm Ambient Temp

Zero Speed

Current Transients

High Voltage Time

Low Current Time

Short Trips

Low Speed

Current Transients

1) On-going fuel cell degradation study using Partial Least Squares (PLS) 

regression model for each team’s Gen 1 fleet.

2) Teams’ PLS models have a high percentage of explained decay rate 

variance, but the models are not robust and results are scattered. 

3) Factor groups associated with stacks that are opposite to the identified 

groups here are not specified.

H*

Starts/Hour

Zero Speed

Short Trips

Low Voltage Time

High Current Time

Current Transients

Cold Starts

Hot Ambient Temp

High Speed

H*

H*

H*

H*

H*: Factor group associated with high decay rate fuel cell stacks

Created: Mar-09-09 9:06 AM

NREL CDP49

0

5

10

15

20

25

Operating Time [%]

Operating Time at Fuel Cell Stack Voltage Levels: DOE Fleet

<50%

50-55%

55-60%

60-65%

65-70%

70-75%

75-80%

80-85%

85-90%

90-95%

95-100%

>100%

% Max Fuel Cell Stack Voltage

All time

Time at low current

NREL CDP07

Created: Mar-09-10 4:13 PM
47 

Figure 46: Fuel cell transient voltage and time change (CDP75) 

Figure 47: Fuel cell transient cycles by mile and by minute (CDP74) 

0 2 4 6 8 10 12 14 16 18 20

0

5

10

15

20

Cycle Per Mile

Trip Frequency [%]

Number of Cycles1 per Trip Mile

0 2 4 6 8 10 12 14 16 18 20

0

10

20

30

40

50

60

Cycle Per Min

Trip Frequency [%]

Number of Cycles1 per Trip Minute

Gen1 Gen2 0

10

20

30

40

Cycle per Mile

Range of Fleet Average Cycle1 per Mile

Gen1 Gen2

1

2

3

4

5

6

7

Cycle per Min

Range of Fleet Average Cycle1 per Min

NREL CDP74

Created: Mar-22-10 4:46 PM 1) A fuel cell voltage transient cycle has a decrease and increase with a minimum delta of 5% max stack voltage.
48 

Figure 48: Fuel cell transient rate by cycle category (CDP76) 

Figure 49: Fuel cell transient voltage changes by cycle category (CDP77) 

0

5

10

15

20

25

30

35

DownUp

SlowUp

SlowDown

SlowDownUp

DownSSUp

Frequency [%]

Transient Cycle1 Count by Category2

0 5 10 15 20 25 30 35 40

0

5

10

15

20

25

30

dV/dt

Frequency [%]

DownUp Cycle1 dV/dT

0 5 10 15 20 25 30 35 40

0

10

20

30

40

50

dV/dt

Frequency [%]

SlowUp Cycle1 dV/dT

0 5 10 15 20 25 30 35 40 0

10

20

30

40

50

dV/dt

Frequency [%]

SlowDown Cycle1 dV/dT

0 5 10 15 20 25 30 35 40 0

10

20

30

40

50

60

dV/dt

Frequency [%]

SlowDownUp Cycle1 dV/dT

0 5 10 15 20 25 30 35 40 0

20

40

60

80

100

dV/dt

Frequency [%]

DownSSUp Cycle1 dV/dT

NREL CDP76

Created: Mar-22-10 4:46 PM 1) A fuel cell voltage transient cycle has a decrease and increase with a minimum delta of 5% max stack voltage.

2) Cycle categories based on cycle up and down times. A slow up or down transient has a time change >= 5 seconds.

 SS = Steady State, where the time change is >= 10 seconds and the voltage change is <= 2.5% max stack voltage.

0

5

10

15

20

25

30

35

DownUp

SlowUp

SlowDown

SlowDownUp

DownSSUp

Frequency [%]

Transient Cycle1 Count by Category2

0

5

10

15

20

-34-30-26-22-18-14-10

-6-2

26

10141822263034

% Voltage Change [%Max Stack Voltage]

Frequency [%]

DownUp Cycle1 dV

0

5

10

15

20

-34-30-26-22-18-14-10

-6-2

26

10141822263034

% Voltage Change [%Max Stack Voltage]

Frequency [%]

SlowUp Cycle1 dV

0

2

4

6

8

10

12

-34-30-26-22-18-14-10

-6-2

26

10141822263034

% Voltage Change [%Max Stack Voltage]

Frequency [%]

SlowDown Cycle1 dV

0

2

4

6

8

10

12

-34-30-26-22-18-14-10

-6-2

26

10141822263034

% Voltage Change [%Max Stack Voltage]

Frequency [%]

SlowDownUp Cycle1 dV

0

5

10

15

20

-34-30-26-22-18-14-10

-6-2

26

10141822263034

% Voltage Change [%Max Stack Voltage]

Frequency [%]

DownSSUp Cycle1 dV

NREL CDP77

Created: Mar-22-10 4:46 PM 1) A fuel cell voltage transient cycle has a decrease and increase with a minimum delta of 5% max stack voltage.

2) Cycle categories based on cycle up and down times. A slow up or down transient has a time change >= 5 seconds.

 SS = Steady State, where the time change is >= 10 seconds and the voltage change is <= 2.5% max stack voltage.
49 

Figure 50: Percentage of trip time at steady state (CDP79) 

Figure 51: Fuel cell transient cycles outside of specified voltage levels (CDP78) 

0 5 10 15 20 25 30 35 40 45 50 0

2

4

6

8

10

12

14

16

18

% Time

Trip Frequency [%]

Percent of Trip Time at Steady State

NREL CDP79

Created: Mar-22-10 4:46 PM 1) SS = Steady State, where the time change is >= 10 seconds and the voltage change is <= 2.5% max stack voltage.

0

5

10

15

20

25

30

35

DownUp

SlowUp

SlowDown

SlowDownUp

DownSSUp

Cycle Frequency [%]

Transient Cycle Count by Category4

Total

<LoV Level2

>HiV Level3

t

V

Example

0 2 4 6 8 10 12 14 16 18 20 0

10

20

30

40

50

60

70

80

Count per Mile

Trip Frequency [%]

Cycles1 Outside of Voltage Levels2,3

<LoV Level2

>HiV Level3

NREL CDP78

Created: Mar-22-10 4:46 PM

1) A fuel cell voltage transient cycle has a decrease and increase with a minimum delta of 5% max stack voltage.

2) The low voltage level is 70% Max Stack Voltage

3) The high voltage level is 90% Max Stack Voltage

4) Cycle categories based on cycle up and down times. A slow up or down transient has a time change >= 5 seconds.

 SS = Steady State, where the time change is >= 10 seconds and the voltage change is <= 2.5% max stack voltage.
50 

Figure 52: Fuel cell electric vehicle maintenance by system (CDP64) 

Figure 53: Driving start time – day (CDP44) 

5% 3%

34%

58%

Fuel Cell Vehicle Events (11574)

18%

8%

50%

24%

Fuel Cell Vehicle Labor (12522 hours)

Vehicle (non-powertrain)

Fuel Cell System

Powertrain

Battery

4%

10%

12%

13%

23%

39%

Fuel Cell System Events (3916)

< 1%

27%

28%

11%

11%

22%

Fuel Cell System Labor (6304 hours)

Thermal Management

Air System

Controls, Electronics, Sensors

Fuel System

Fuel Cell Stack

Other

NREL CDP64

Created: Mar-10-10 10:34 AM

Fuel Cell Vehicle Maintenance Events and Labor Hours

Driving Start Time - Day: DOE Fleet

9%

3

12

9

6

Total Driving3 % of driving trips b/t 6 AM & 6 PM: 85.3% Events = 295222

1. Driving trips between 6 AM & 6 PM

2. The outer arc is set at 12 % total Driving.

3. Some events not recorded/detected due to data noise or incompleteness.

AM PM

% of NHTS trips b/t 6 AM & 6 PM: 81.5%

NREL CDP44

DOE Fleet

NHTS

Created: Mar-09-10 4:15 PM

2001 NHTS Data Includes Car, Truck, Van, & SUV day trips

ASCII.csv Source: http://nhts.ornl.gov/download.shtml#2001
51 

Figure 54: Driving start time – night (CDP51) 

Figure 55: Driving by day of week (CDP45) 

Driving Start Time - Night: DOE Fleet

4%

3

12

9

6

Total Driving3 % of driving trips b/t 6 PM & 6 AM: 14.7% Events = 295222

1. Driving trips between 6 PM & 6 AM

2. The outer arc is set at 12 % total Driving.

3. Some events not recorded/detected due to data noise or incompleteness.

PM AM

% of NHTS trips b/t 6 PM & 6 AM: 18.4%

NREL CDP51

DOE Fleet

NHTS

Created: Mar-09-10 4:15 PM

2001 NHTS Data Includes Car, Truck, Van, & SUV day trips

ASCII.csv Source: http://nhts.ornl.gov/download.shtml#2001

Sun Mon Tues Wed Thur Fri Sat 0

2

4

6

8

10

12

14

16

18

20

Driving Trips by Day of Week: DOE Fleet

% of Driving Trips in a Day

NREL CDP45 Day

DOE Fleet

NHTS

Created: Mar-09-10 4:15 PM

2001 NHTS Data Includes Car, Truck, Van, & SUV day trips

ASCII.csv Source: http://nhts.ornl.gov/download.shtml#2001
52 

Figure 56: Safety reports – vehicles (CDP09) 

Figure 57: Range of ambient temperature during vehicle operation (CDP21) 

0

1

2

3

Number of Reports

Safety Reports - Vehicle Operation

Tank Scratch

Traffic Accident

H2 Leak - During Fueling

H2 Alarm - Fuel System

H2 Alarm - Passenger Compartment

Created: Mar-10-10 2:35 PM

NREL CDP09

0 2 4 6 8 10 12 -30

-20

-10

0

10

20

30

40

50

60

1.4 % trips below 0 oC

Max Op = 140.0 o

F

Min Op = -5.8 o

F

28.2 % trips above 28 o

C

Trip Frequency [%]

Temperature [oC]

Average Ambient Trip Temperature: DOE Fleet

NREL CDP21

Created: Mar-09-10 4:12 PM
53 

Figure 58: Fuel cell start times from sub-freezing soak conditions (CDP05) 

Figure 59: Time between trips & ambient temperature (CDP19) 

12 hr Equilibrium 12 hr Equilibrium 0

100

200

300

400

500

600

Time to Drive Away Time to Max FC Power

Time [s]

Fuel Cell Vehicle Start Time from Sub-Freezing Soak Condition1

NREL CDP05

Created: Sep-08-09 10:54 AM

(1) Learning Demo soak temperature for freeze tests were between -9 and -20 oC

(2) 2010 & 2015 DOE MYPP Cold Start Up Time Target: 30 seconds to 50% of rated power from -20 o

C (soak duration not specified).

0-10 10-30 30-60 60-360 >360 0

5

10

15

20

25

30

35

Time [min]

Trip Frequency [%]

Time Between Trips with Ambient Temperature: DOE Fleet

<0oC

0-10oC

10-24oC

24-40oC

>40oC

NREL CDP19

Created: Mar-09-10 4:13 PM
54 

Figure 60: Difference between tank and ambient temperature prior to refueling (CDP72) 

Figure 61: Vehicle operating hours (CDP22) 

-20 0 20 40 60 -20

-10

0

10

20

30

40

50

60

Ambient Air Temperature [deg C]

Tank Temperature [deg C]

Tank vs. Ambient Air Temps Prior to Refueling

Frequency

50

100

150

200

250

300

-40 -20 0 20 40 0

500

1000

1500

2000

Delta Temperature [deg C]

Count

Delta Temperature: Tank minus Ambient

Delta Temp Histogram

Normal Distribution Fit

0

0.02

0.04

0.06

0.08

Density

Mean= -3.751

Std Dev= 6.129

NREL CDP72

Created: Mar-11-10 10:24 AM

-This CDP created in support of SAE J2601 related to refueling

-Temperatures are prior to refueling and exclude data within 4 hours of a previous fill

-The plot to the left excludes ambient temperatures less than -5 deg C

0

5

10

15

20

25

30

35

40

Number of Vehicles

Total Vehicle Hours

Vehicle Hours: All OEMs, Gen 1 and Gen 2

In Service

Retired (1)

Total Vehicle Hours = 106,413

Through 2009 Q4

Created: Mar-09-10 02:36 PM

(1) Retired vehicles have left DOE fleet and are no longer providing data to NREL

Some project teams concluded in Fall/Winter 2009

NREL CDP22
55 

Figure 62: Vehicles vs. miles traveled (CDP23) 

Figure 63: Cumulative vehicle miles traveled (CDP24) 

0

5

10

15

20

25

30

35

40

45

Number of Vehicles

Total Vehicle Miles

Vehicle Miles: All OEMs, Gen 1 and 2

In Service

Retired (1)

Total Vehicle Miles Traveled = 2,580,382

Through 2009 Q4

Created: Mar-09-10 03:16 PM

NREL CDP23 (1) Retired vehicles have left DOE fleet and are no longer providing data to NREL

Some project teams concluded in Fall/Winter 2009

2,580,382 

-

250,000 

500,000 

750,000 

1,000,000 

1,250,000 

1,500,000 

1,750,000 

2,000,000 

2,250,000 

2,500,000 

2,750,000 

Vehicle Miles Traveled

Cumulative Vehicle Miles: All OEMs, Gen 1 and Gen 2

Created: Mar-09-10 03:16 PM

Through 2009 Q4

NREL CDP24
56 

Figure 64: Onsite hydrogen production efficiency (CDP13) 

Figure 65: Onsite hydrogen production efficiency vs. capacity utilization (CDP60) 

On-Site Natural Gas Reforming On-Site Electrolysis 0

10

20

30

40

50

60

70

80

2010 MYPP Target

2015 MYPP Target

2012 MYPP Target

2017 MYPP Target

Production Efficiency (LHV %)

Hydrogen Production Conversion Efficiency1

Average Station Efficiency

Quarterly Efficiency Data

Highest Quarterly Efficiency

Efficiency Probability Distribution2

NREL CDP13

Created: Mar-09-10 3:16 PM

1

Production conversion efficiency is defined as the energy of the hydrogen out of the process (on an LHV basis) divided by the sum of

the energy into the production process from the feedstock and all other energy as needed. Conversion efficiency does not include

energy used for compression, storage, and dispensing.

2

The efficiency probability distribution represents the range and likelihood of hydrogen production conversion efficiency based on

monthly conversion efficiency data from the Learning Demonstration.

0 10 20 30 40 50 60 70 80 90 100 0

10

20

30

40

50

60

70

Production Capacity Utilization1 [%]

Production Conversion Efficiency 2 [%]

Monthly Production Conversion Efficiency vs Utilization

Electrolysis Data

Electrolysis Fit3

Electrolysis Fit Confidence

Natural Gas Data

Natural Gas Fit3

Natural Gas Fit Confidence

NREL CDP60

Created: Mar-09-10 3:34 PM

1) 100% production utilization assumes operation 24 hrs a day, 7 days a week

2) Production conversion efficiency is defined as the energy of the hydrogen out of the process (on a LHV basis) divided by the sum of the energy into the production

process from the feedstock and all other energy as needed. Conversion efficiency does not include energy used for compression, storage, and dispensing.

3) High correlation with electrolysis data (R2

 = 0.82) & low correlation with natural gas data (R2 = 0.060)
57 

Figure 66: Learning Demonstration vehicle greenhouse gas emissions (CDP62) 

Figure 67: Refueling station compressor efficiency (CDP61) 

0

100

200

300

400

500

600

700

WTW GHG Emissions (g CO2-eq/mi)

Learning Demonstration Fuel Cycle Well-to-Wheels Greenhouse Gas Emissions1

Baseline Conventional Mid-Size Passenger Car2

Baseline Conventional Mid-Size SUV2

Average WTW GHG Emissions (Learning Demo)

Minimum WTW GHG Emissions (Learning Demo)

WTW GHG Emissions (100% Renewable Electricity)

WTW GHG Probability Based on Learning Demo3

NREL CDP62

Created: Mar-08-10 4:16 PM

On-Site Natural Gas Reforming On-Site Electrolysis(4)

1. Well-to-Wheels greenhouse gas emissions based on DOE's GREET model, version 1.8b. Analysis uses default GREET values except for FCV fuel economy, hydrogen

production conversion efficiency, and electricity grid mix. Fuel economy values are the Gen 1 and Gen 2 window-sticker fuel economy data for all teams (as used in CDP #6);

conversion efficiency values are the production efficiency data used in CDP #13.

2. Baseline conventional passenger car and light duty truck GHG emissions are determined by GREET 1.8b, based on the EPA window-sticker fuel economy of a conventional

gasoline mid-size passenger car and mid-size SUV, respectively. The Learning Demonstration fleet includes both passenger cars and SUVs.

3. The Well-to-Wheels GHG probability distribution represents the range and likelihood of GHG emissions resulting from the hydrogen FCV fleet based on window-sticker fuel

economy data and monthly conversion efficiency data from the Learning Demonstration.

4. On-site electrolysis GHG emissions are based on the average mix of electricity production used by the Learning Demonstration production sites, which includes both

grid-based electricity and renewable on-site solar electricity. GHG emissions associated with on-site production of hydrogen from electrolysis are highly dependent on

electricity source. GHG emissions from a 100% renewable electricity mix would be zero, as shown. If electricity were supplied from the U.S. average grid mix, average GHG

emissions would be 1330 g/mile.

On-Site Compression Energy 0

10

20

30

40

50

60

70

Compression Energy (MJ/kg)

On-Site Compression Efficiency 0

10

20

30

40

50

60

70

80

90

100

2010 MYPP Compression Target

2015 MYPP Compression Target

Compression Efficiency (%)

On-Site Hydrogen Compression Efficiency1 and Energy Use

Average Station Compression Efficiency

Quarterly Compression Efficiency Data

Highest Quarterly Compression Efficiency

Average Station Compression Energy

Quarterly Compression Energy Data

Lowest Quarterly Compression Energy

NREL CDP61

Created: Mar-11-10 9:41 AM

1

Consistent with the MYPP, compression efficiency is defined as the energy of the hydrogen out of the process (on an LHV basis) divided by the sum of the

energy of the hydrogen output plus all other energy needed for the compression process. Data shown for on-site hydrogen production and storage

facilities only, not delivered hydrogen sites.

Compression Energy Requirement:

On average, 11.3% of the energy

contained in the hydrogen fuel is

required for the compression

process.
58 

Figure 68: Hydrogen production cost vs. process (CDP15) 

Figure 69: Hydrogen quality index (CDP27) 

0

2

4

6

8

10

12

14

16

Projected Early Market 1500 kg/day Hydrogen Cost1

$/kg

Natural Gas Reforming2 Electrolysis2

2015 DOE Hydrogen Program Goal Range3

Median

25th & 75th Percentile

10th & 90th Percentile

Created: Jan-19-10 11:08 AM

(1) Reported hydrogen costs are based on estimates of key cost elements from Learning Demonstration energy company partners and represent the

cost of producing hydrogen on-site at the fueling station, using either natural gas reformation or water electrolysis, dispensed to the vehicle. Costs

reflect an assessment of hydrogen production technologies, not an assessment of hydrogen market demand.

(2) Hydrogen production costs for 1500 kg/day stations developed using DOE’s H2A Production model, version 2.1. Cost modeling represents the

lifetime cost of producing hydrogen at fueling stations installed during an early market rollout of hydrogen infrastructure and are not reflective of the

costs that might be seen in a fully mature market for hydrogen installations. Modeling uses default H2A Production model inputs supplemented with

feedback from Learning Demonstration energy company partners, based on their experience operating on-site hydrogen production stations. 

H2A-based Monte Carlo simulations (2,000 trials) were completed for both natural gas reforming and electrolysis stations using default H2A values and

10th percentile to 90th percentile estimated ranges for key cost parameters as shown in the table. Capacity utilization range is based on the capabilities

of the production technologies and could be significantly lower if there is inadequate demand for hydrogen.

(3) DOE has a hydrogen cost goal of $2-$3/kg for future (2015) 1500 kg/day hydrogen production stations installed at a rate of 500 stations per year.

Key H2 Cost Elements and Ranges 

Input Parameter Minimum 

(P10) 

Maximum

(P90) 

Facility Direct Capital Cost $10M $25M 

Facility Capacity Utilization 85% 95% 

Annual Maintenance & Repairs $150K $600K 

Annual Other O&M $100K $200K 

Annual Facility Land Rent $50K $200K 

Natural Gas Prod. Efficiency (LHV) 65% 75% 

Electrolysis Prod. Efficiency (LHV) 35% 62% 

NREL CDP15

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del.

99.7

99.75

99.8

99.85

99.9

99.95

100

Calculated H2 Index (%)

H2 Calculated Quality Index by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Calculated Data

NREL CDP27

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
59 

Figure 70: Hydrogen fuel constituents – all (CDP28) 

Figure 71: Hydrogen fuel constituents – sulfur (CDP28) 

0 2 4 6 8 10 12 14 16 18 20

Particulates 

μg/L

H2

 Fuel Constituents

Data Range SAE J2719 APR2008 Guideline Measured Less Than or Equal To (Detection Limited)

0 500 1000 1500 2000 2500 3000

(N2+He+Ar) 

He 

(Ar+N2) 

0 5 10 15 20 25 30 35 40

H2O 

Total HC 

O2 

CO2 

CO 

NH3 

μmol/mol (ppm)

0 10 20 30 40 50 60 70 80

Total S* 

NREL CDP28 nmol/mol (ppb) Created: Mar-10-10 11:05 AM Data is from Learning Demonstration and California Fuel Cell Partnership testing

*Total S calculated from SO2, COS, H2S, CS2, and Methyl Mercaptan (CH3SH).

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

10

20

30

40

50

60

70

Total S* (nmol/mol)(ppb)

Total S* (nmol/mol)(ppb)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

*Total S calculated from SO2, COS, H2S, CS2, and Methyl Mercaptan (CH3SH).

Year 1 Year 2 Year 3 Year 4 Year 5
60 

Figure 72: Hydrogen fuel constituents – total hydrocarbons (CDP28) 

Figure 73: Hydrogen fuel constituents – total halogenates (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

0.5

1

1.5

2

Total HC (μmol/mol)(ppm)

Total HC (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

5

10

15

20

25

Total Halogenates (μmol/mol)(ppm)

Total Halogenates (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
61 

Figure 74: Hydrogen fuel constituents – particulate concentration (CDP28) 

Figure 75: Hydrogen fuel constituents – oxygen (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

2

4

6

8

10

12

14

16

18

20

22

Particulate Concentration ( μg/L)

Particulate Concentration (μg/L)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

5

10

15

20

25

30

35

40

O2

(μmol/mol)(ppm)

O2(μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
62 

Figure 76: Hydrogen fuel constituents – nitrogen (CDP28) 

Figure 77: Hydrogen fuel constituents – nitrogen + helium + argon (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

500

1000

1500

2000

2500

N2 (μmol/mol)(ppm)

N2 (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

500

1000

1500

2000

2500

3000

N2+He+Ar (μmol/mol)(ppm)

N2+He+Ar (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
63 

Figure 78: Hydrogen fuel constituents – particulate size (CDP28) 

Figure 79: Hydrogen fuel constituents – helium (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

5000

10000

15000

20000

25000

30000

Particulate Size ( μm)

Particulate Size (μm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

50

100

150

200

250

300

He (μmol/mol)(ppm)

He (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
64 

Figure 80: Hydrogen fuel constituents – water (CDP28) 

Figure 81: Hydrogen fuel constituents – formic acid (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

5

10

15

H2O (μmol/mol)(ppm)

H2O (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

0.05

0.1

0.15

0.2

Formic acid (μmol/mol)(ppm)

Formic acid (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
65 

Figure 82: Hydrogen fuel constituents – formaldehyde (CDP28) 

Figure 83: Hydrogen fuel constituents – CO (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

0.02

0.04

0.06

0.08

0.1

Formaldehyde (μmol/mol)(ppm)

Formaldehyde (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

0.2

0.4

0.6

0.8

1

CO (μmol/mol)(ppm)

CO (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
66 

Figure 84: Hydrogen fuel constituents – CO2 (CDP28) 

Figure 85: Hydrogen fuel constituents – total (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

1

2

3

4

5

6

7

8

9

CO2 (μmol/mol)(ppm)

CO2 (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

500

1000

1500

2000

2500

3000

Calcultated Total Constituents ( μmol/mol)(ppm)

Calcultated Total Constituents (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Calculated Data

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
67 

Figure 86: Hydrogen fuel constituents – argon + nitrogen (CDP28) 

Figure 87: Hydrogen fuel constituents – argon (CDP28) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

500

1000

1500

2000

2500

Ar+N2 (μmol/mol)(ppm)

Ar+N2 (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

50

100

150

200

Ar (μmol/mol)(ppm)

Ar (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5
68 

Figure 88: Hydrogen fuel constituents – ammonia (CDP28) 

Figure 89: Infrastructure maintenance (CDP30) 

Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. Ref. Elec. Del. 0

1

2

3

4

5

6

NH3 (μmol/mol)(ppm)

NH3 (μmol/mol)(ppm)

Non-H2

 Constituents by Year and Production Method

On-Site NG Reformer (Data Range)

On-Site Electrolysis (Data Range)

Delivered (Data Range)

SAE J2719 APR2008 Guideline

Measured

Less Than or Equal To (Detection Limited)

NREL CDP28

Created: Mar-10-10 11:07 AM

Data is from Learning Demonstration and California Fuel Cell Partnership testing

Year 1 is 2005Q3-2006Q2, Year 2 is 2006Q3-2007Q2, Year 3 is 2007Q3-2008Q2, Year 4 is 2008Q3-2009Q2, and Year 5 is 2009Q3-2009Q4

Year 1 Year 2 Year 3 Year 4 Year 5

0 20 40 60 80 100 120 140 160 180 200

Adjustment

Check Only

Other

Repair

Replacement

Maintenance: Average Labor Hours Per Station Since Inception

Through 2009 Q4

Scheduled

Un-Scheduled

0 5 10 15 20 25 30 35 40

Adjustment

Check Only

Other

Repair

Replacement

Maintenance: Average Number of Events Per Station Since Inception

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

# of Events

Hours

Comparison of Scheduled/Un-Scheduled Maintenance

NREL CDP30

Created: Mar-10-10 9:30 AM
69 

Figure 90: Hydrogen fueling station maintenance by system (CDP63) 

Figure 91: Safety reports – infrastructure (CDP20) 

13%

13%

18%

22%

By Number of Events

Total Number of Events = 2491

20%

12%

17%

21%

By Labor Hours

Total Hours = 11430

system control & safety

compressor

reformer

electrolyzer

dispenser

other

valves & piping

electrical

storage

NREL CDP63

Created: Mar-10-10 10:31 AM

Hydrogen Fueling Station Maintenance

0 50 100 150 200 250 300

Non-Event

Near Miss

Incident

Number of Reports

Severity

Total Infrastructure Safety Reports by Severity

and Report Type Through 2009 Q4

Alarms Only

Automatic System Shutdown

Electrical Issue

Equipment Malfunction

False Alarm/Mischief

H2 Release - Minor, NO Ignition

H2 Release - Significant, NO Ignition

Manual System Shutdown

Non-H2 Release

Site Power Outage

Structural Issue

System Trouble, not Alarm

NREL CDP20

Created: Mar-11-10 2:45 PM

An INCIDENT is an event that results in:

 - a lost time accident and/or injury to personnel

 - damage/unplanned downtime for project equipment, facilities or property

 - impact to the public or environment

 - any hydrogen release that unintentionally ignites or is sufficient to sustain a flame if ignited

 - release of any volatile, hydrogen containing compound (other than the hydrocarbons used as common fuels)

A NEAR-MISS is:

 - an event that under slightly different circumstances could have become an incident

 - unplanned H2 release insufficient to sustain a flame
70 

Figure 92: Primary factors of infrastructure reports (CDP37) 

Figure 93: Average refuelings between infrastructure safety reports (CDP35) 

0 50 100 150 200 250 300

Non-Event

Near Miss

Incident

Number of Reports

Severity

Primary Factors of Infrastructure Safety Reports

Through 2009 Q4

Calibration/Settings/ Software Controls

Design Flaw

Electrical Power to Site

Environment (Weather, Power Disruption, Other)

False Alarm

Inadequate Training, Protocol, SOP

Inadequate/ Non-working Equipment

Maintenance Required

Mischief, Vandalism, Sabotage

New Equipment Materials

Not Yet Determined

Operator/Personnel Error

System Manually Shutdown

NREL CDP37

Created: Mar-11-10 2:45 PM

An INCIDENT is an event that results in:

 - a lost time accident and/or injury to personnel

 - damage/unplanned downtime for project equipment, facilities or property

 - impact to the public or environment

 - any hydrogen release that unintentionally ignites or is sufficient to sustain a flame if ignited

 - release of any volatile, hydrogen containing compound (other than the hydrocarbons used as common fuels)

A NEAR-MISS is:

 - an event that under slightly different circumstances could have become an incident

 - unplanned H2 release insufficient to sustain a flame

0

2

4

6

8

10

12

14

16

18

20

22

24

Number of Stations

Infrastructure Safety Trend and Number of Stations Through 2009 Q4

05Q2

05Q3

05Q4

06Q1

06Q2

06Q3

06Q4

07Q1

07Q2

07Q3

07Q4

08Q1

08Q2

08Q3

08Q4

09Q1

09Q2

09Q3

09Q4

Number of Stations

Avg Refuelings Between Safety Reports

0

100

200

300

400

500

600

Avg # of Refuelings Between Safety Reports

7 11

32 34

88 102 115

47

68

124

101

57 54

73

51

138

447

121

198

NREL CDP35

Created: Mar-23-10 2:43 PM Reporting Period
71 

Figure 94: Type of infrastructure safety report by quarter (CDP36) 

Figure 95: Refueling times (CDP38) 

0

10

20

30

40

50

Number of Reports

Type of Infrastructure Safety Reports by Quarter Through 2009 Q4

05Q2

05Q3

05Q4

06Q1

06Q2

06Q3

06Q4

07Q1

07Q2

07Q3

07Q4

08Q1

08Q2

08Q3

08Q4

09Q1

09Q2

09Q3

09Q4

Incident

Near Miss

Non-Event

Number of Stations

Avg # Reports/Station

NREL CDP36

Created: Mar-23-10 2:15 PM

Reporting Period An INCIDENT is an event that results in:

 - a lost time accident and/or injury to personnel

 - damage/unplanned downtime for project equipment, facilities or property

 - impact to the public or environment

 - any hydrogen release that unintentionally ignites or is sufficient to sustain a flame if ignited

 - release of any volatile, hydrogen containing compound (other than the hydrocarbons used as common fuels)

A NEAR-MISS is:

 - an event that under slightly different circumstances could have become an incident

 - unplanned H2 release insufficient to sustain a flame

0 2 4 6 8 10 12 14 16 18 20 0

500

1000

1500

2000

2500

3000

3500

Time (min)

Number of Fueling Events

Histogram of Fueling Times

All Light Duty Through 2009Q4

Average = 3.26 min

86% <5 min

 2006 MYPP Tech Val Milestone (5 kg in 5 min at 350 bar)

 2012 MYPP Tech Val Milestone (5 kg in 3 min at 350 bar)

NREL CDP38

Created: Mar-09-10 3:18 PM
72 

Figure 96: Refueling amounts (CDP39) 

Figure 97: Refueling rates (CDP18) 

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0

100

200

300

400

500

600

700

800

900

1000

Amount Fueled (kg)

Number of Fueling Events

Histogram of Fueling Amounts

All Light Duty Through 2009Q4

Average = 2.13 kg

NREL CDP39

Created: Mar-09-10 3:18 PM

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0

200

400

600

800

1000

1200

1400

1600

1800

Avg Fuel Rate (kg/min)

Number of Fueling Events

Histogram of Fueling Rates

All Light Duty Through 2009Q4

5 minute fill of

5 kg at 350 bar

3 minute fill of

5 kg at 350 bar

25464 Events

Average = 0.77 kg/min

23% >1 kg/min

2006 MYPP Tech Val Milestone

2012 MYPP Tech Val Milestone

NREL CDP18

Created: Mar-09-10 3:18 PM
73 

Figure 98: Fueling rates – communication and non-communication fills (CDP29) 

Figure 99: Fueling rates – 350 and 700 bar (CDP14) 

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0

500

1000

1500

2000

2500

Avg Fuel Rate (kg/min)

Number of Fueling Events

Histogram of Fueling Rates

Comm vs Non-Comm Fills - All Light Duty Through 2009Q4

5 minute fill of

5 kg at 350 bar

3 minute fill of

5 kg at 350 bar

Fill Type Avg (kg/min) %>1 

------------- ------------------ -------

Comm 0.86 30%

Non-Comm 0.66 12%

Comm

Non-Comm

2006 MYPP Tech Val Milestone

2012 MYPP Tech Val Milestone

NREL CDP29

Created: Mar-09-10 3:08 PM

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0

500

1000

1500

2000

2500

Avg Fuel Rate (kg/min)

Number of Fueling Events

Histogram of Fueling Rates

350 vs 700 bar Fills - All Light Duty Through 2009Q4

5 minute fill of

5 kg at 350 bar

3 minute fill of

5 kg at 350 bar

Fill Type Avg (kg/min) %>1 Count

------------- ------------------ ------- --------

350 bar 0.82 29% 19659

700 bar 0.63 4% 5590

350 bar

700 bar

2006 MYPP Tech Val Milestone

2012 MYPP Tech Val Milestone

NREL CDP14

Created: Mar-09-10 3:10 PM
74 

Figure 100: Refueling data by year (CDP52) 

Figure 101: Hydrogen tank level at refueling (CDP40) 

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0

100

200

300

400

500

600

700

Avg Fuel Rate (kg/min)

Number of Fueling Events

Histogram of Fueling Rates

All Light Duty by Year Through 2009Q4

5 minute fill of

5 kg at 350 bar

3 minute fill of

5 kg at 350 bar

Year Avg (kg/min) %>1 

------- ----------------- -------

2005 0.66 16%

2006 0.74 21%

2007 0.81 26%

2008 0.77 23%

2009 0.77 22%

2005

2006

2007

2008

2009

2006 MYPP Tech Val Milestone

2012 MYPP Tech Val Milestone

NREL CDP52

Created: Mar-09-10 3:35 PM

Tank Levels: DOE Fleet

14%

E F

NREL CDP40

Created: Mar-09-10 4:14 PM

Total refuelings1 = 27113

1. Some refueling events not recorded/detected due to data noise or incompleteness.

Median Tank Level (At Fill) = 42%

2. The outer arc is set at 20% total refuelings.

3. If tank level at fill was not available, a complete fill up was assumed.
75 

Figure 102: Refueling tank levels – medians (CDP41) 

Figure 103: Refueling by time of day (CDP42) 

E F

Tank Level Medians (At Fill): DOE Fleet, All Vehicles

NREL CDP41

Created: Mar-09-10 4:14 PM

Total refuelings1 = 27113

1. Some refueling events not recorded/detected due to data noise or incompleteness.

2. If tank level at fill was not available, a complete fill up was assumed.

Refueling by Time of Day: DOE Fleet

9%

3

12

9

6

Total Fill3 % of fills b/t 6 AM & 6 PM: 89.7% Events = 22657

1. Fills between 6 AM & 6 PM

2. The outer arc is set at 12 % total Fill.

3. Some events not recorded/detected due to data noise or incompleteness.

AM PM

NREL CDP42

Created: Mar-09-10 4:14 PM
76 

Figure 104: Refueling by time of night (CDP50) 

Figure 105: Refueling by day of week (CDP43) 

Refueling by Time of Night: DOE Fleet

3%

3

12

9

6

Total Fill3 % of fills b/t 6 PM & 6 AM: 10.3% Events = 22657

1. Fills between 6 PM & 6 AM

2. The outer arc is set at 12 % total Fill.

3. Some events not recorded/detected due to data noise or incompleteness.

PM AM

NREL CDP50

Created: Mar-09-10 4:14 PM

Sun Mon Tues Wed Thur Fri Sat 0

5

10

15

20

Fills by Day of Week: DOE Fleet

% of Fills in a Day

NREL CDP43 Day Created: Mar-09-10 4:14 PM
77 

Figure 106: Cumulative hydrogen produced or dispensed (CDP26) 

0

5

10

15

20

25

0

20

40

60

80

100

120

140

160

Cumulative Number of Stations

Mass of Hydrogen* 

(1000 kg)

Calendar Quarter

Cumulative Hydrogen Produced or Dispensed 

Through 2009 Q4

Cumulative Hydrogen

Number of Stations

NREL CDP26

Created 2010-Mar-22 2:50pm

*Some project teams 

concluded in Fall/Winter 2009
F1147-E(10/2008) 

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September 2010

2. REPORT TYPE

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3. DATES COVERED (From - To)

 

4. TITLE AND SUBTITLE

Learning Demonstration Interim Progress Report – July 2010

5a. CONTRACT NUMBER

DE-AC36-08-GO28308

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

K. Wipke, S. Sprik, J. Kurtz, and T. Ramsden

5d. PROJECT NUMBER

NREL/TP-560-49129

5e. TASK NUMBER

H270.8100

5f. WORK UNIT NUMBER

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National Renewable Energy Laboratory

1617 Cole Blvd.

Golden, CO 80401-3393

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NREL/TP-560-49129

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13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

This report discusses key results based on data through December 2009 from the U.S. Department of Energy’s 

(DOE) Controlled Hydrogen Fleet and Infrastructure Validation and Demonstration Project, also referred to as the 

National Fuel Cell Electric Vehicle (FCEV) Learning Demonstration. The report serves to help transfer knowledge 

and lessons learned within various parts of DOE’s hydrogen program, as well as externally to other stakeholders. It is 

the fourth such report in a series, with previous reports being published in July 2007, November 2007, and April 

2008. 

15. SUBJECT TERMS

Controlled Hydrogen Fleet and Infrastructure Validation and Demonstration Project; National Fuel Cell Electric 

Vehicle (FCEV) Learning Demonstration; California Hydrogen Infrastructure Project; Fuel Cell Stack Durability; Fuel 

Economy; Fuel Cell Efficiency

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