A national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

National Renewable Energy Laboratory 

Innovation for Our Energy Future 

Learning Demonstration Progress 

Report – September 2007 

K. Wipke, S. Sprik, J. Kurtz, and H. Thomas 

Technical Report 

NREL/TP-560-42264 

November 2007 

NREL is operated by Midwest Research Institute ● Battelle Contract No. DE-AC36-99-GO10337 
National Renewable Energy Laboratory

1617 Cole Boulevard, Golden, Colorado 80401-3393 

303-275-3000 • www.nrel.gov 

Operated for the U.S. Department of Energy 

Office of Energy Efficiency and Renewable Energy 

by Midwest Research Institute • Battelle 

Contract No. DE-AC36-99-GO10337

Technical Report 

NREL/TP-560-42264 

November 2007 

Learning Demonstration Progress 

Report – September 2007 

K. Wipke, S. Sprik, J. Kurtz, and H. Thomas 

Prepared under Task No. H270.8100 
NOTICE

This report was prepared as an account of work sponsored by an agency of the United States government. 

Neither the United States government nor any agency thereof, nor any of their employees, makes any 

warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or 

usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not 

infringe privately owned rights. Reference herein to any specific commercial product, process, or service by 

trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, 

recommendation, or favoring by the United States government or any agency thereof. The views and 

opinions of authors expressed herein do not necessarily state or reflect those of the United States 

government or any agency thereof. 

Available electronically at http://www.osti.gov/bridge

Available for a processing fee to U.S. Department of Energy 

and its contractors, in paper, from: 

U.S. Department of Energy 

Office of Scientific and Technical Information 

P.O. Box 62 

Oak Ridge, TN 37831-0062 

phone: 865.576.8401 

fax: 865.576.5728 

email: mailto:reports@adonis.osti.gov

Available for sale to the public, in paper, from: 

U.S. Department of Commerce 

National Technical Information Service 

5285 Port Royal Road 

Springfield, VA 22161 

phone: 800.553.6847 

fax: 703.605.6900 

email: orders@ntis.fedworld.gov

online ordering: http://www.ntis.gov/ordering.htm

Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste
TABLE OF CONTENTS 

1 Learning Demonstration Progress Report – September 2007 ......................................1

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

1.2 Approach .........................................................................................................................2 

1.3 Key Analysis Accomplishments in FY 2007 ..................................................................3 

2 Results.................................................................................................................................4

2.1 Vehicle Results................................................................................................................5 

2.2 Infrastructure Results ......................................................................................................9 

2.3 Conclusions and Future Directions ...............................................................................12 

2.4 Related Publications/Presentations from FY07.............................................................13 

2.5 Acronyms ......................................................................................................................14 

2.6 Composite Data Products Referenced in Previous Discussion .....................................15 

LIST OF FIGURES 

Figure 1: Photographs of the Four Teams' First-Generation Vehicles with Small Inset Photos 

Showing the Second-Generation Vehicles....................................................................1 

Figure 2: Four Types of Hydrogen Production and Refueling Facilities with Examples.............2 

Figure 3: Process Flow for Hydrogen Secure Data Center Analysis and Results, Overlaid on 

Top of Quantity of Data Received at HSDC.................................................................3 

Figure 4: Fuel Cell System Efficiency at ~25% Net Power .......................................................15 

Figure 5: Fuel Cell Operating Powers ........................................................................................15 

Figure 6: Learning Demonstration Fuel Cell Vehicle Fuel Economy ........................................16 

Figure 7: Learning Demonstration Fuel Cell Vehicle Range .....................................................16 

Figure 8: Percentage of Theoretical Range Traveled Between Refuelings................................17 

Figure 9: Effective Vehicle Range..............................................................................................17 

Figure 10: Fuel Stack Hours Accumulated and Projected Hours to 10% Voltage Degradation ..18 

Figure 11: Primary Factors Affecting Learning Demo Fleet Fuel Cell Degradation ...................18 

Figure 12: Primary Factors Affecting Learning Demo Team Fuel Cell Degradation ..................19 

Figure 13: Driving Start Time – Day............................................................................................19 

Figure 14: Driving Start Time – Night .........................................................................................20 

Figure 15: Driving by Day of Week .............................................................................................20 

Figure 16: Trip Length..................................................................................................................21 

Figure 17: Safety Reports – Vehicles ...........................................................................................21 

Figure 18: Range of Ambient Temperature during Vehicle Operation ........................................22 

Figure 19: Vehicle Operating Hours.............................................................................................22 

Figure 20: Number Vehicles vs. Miles Traveled ..........................................................................23 

Figure 21: Cumulative Vehicle Miles Traveled............................................................................23 

Figure 22: Vehicle Hydrogen Storage Technologies....................................................................24 

Figure 23: Hydrogen Quality Index Scatter Plot ..........................................................................24 

Figure 24: Hydrogen Impurities Scatter Plot................................................................................25 

Figure 25: Infrastructure Maintenance..........................................................................................25 

Figure 26: Infrastructure Safety Reports by Severity and Report Type .......................................26 

Figure 27: Primary Factors of Infrastructure Safety Reports........................................................26 

Figure 28: Average Refuelings between Infrastructure Safety Reports .......................................27 

 iii
Figure 29: Type of Infrastructure Safety Report by Quarter ........................................................27 

Figure 30: Refueling Times..........................................................................................................28 

Figure 31: Refueling Amounts......................................................................................................28 

Figure 32: Refueling Rates ...........................................................................................................29 

Figure 33: Compressed and Liquid Hydrogen Tank Cycle Life...................................................29 

Figure 34: Compressed and Liquid Hydrogen Tank Weight-Percent ..........................................30 

Figure 35: Compressed and Liquid Hydrogen Tank Volumetric Capacity ..................................30 

Figure 36: Fueling Rates – Communication and Non-Communication Fills...............................31 

Figure 37: H2 Tank Level at Refueling.........................................................................................31 

Figure 38: Refueling Tank Levels – Medains...............................................................................32 

Figure 39: Refueling by Time of Day...........................................................................................32 

Figure 40: Refueling by Time of Night ........................................................................................33 

Figure 41: Refueling by Day of Week..........................................................................................33 

Figure 42: Cumulative Hydrogen Produced or Dispensed ...........................................................34 

Figure 43: Number and Types of Hydrogen Stations Being Demonstrated .................................34 

Figure 44: Number of Stations Online by Quarter........................................................................35 

 iv
1 Learning Demonstration Progress Report – September 2007 

1.1 Introduction 

This purpose of this report is to document and discuss key results to date from the U.S. 

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

Demonstration Project, also referred to as the fuel cell vehicle (FCV) and infrastructure 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. Other mechanisms have included: briefings to FreedomCAR and Fuels technical 

teams, presentations at technical conferences, postings of individual results to the National 

Renewable Energy Laboratory’s (NREL) Web site, presentations at DOE’s Annual Merit 

Review, and participation in groups such as the California Hydrogen Business Council, US Fuel 

Cell Council Joint Hydrogen Quality Task Force, and various California Fuel Cell Partnership 

working groups. 

Figure 1: Photographs of the Four Teams' First-Generation Vehicles with Small Inset Photos 

Showing the Second-Generation Vehicles 

The primary goal of this project is to validate vehicle/infrastructure systems using hydrogen as a 

transportation fuel for light-duty vehicles. This means validating the use of FCVs and hydrogen 

refueling infrastructure under real-world conditions using multiple sites, varying climates, and a 

variety of sources for hydrogen. See Figure 1 for photographs of the first-generation vehicles 

 1
and logos of the four teams and Figure 2 for photographs representing examples of the four types 

of hydrogen refueling stations. 

Figure 2: Four Types of Hydrogen Production and Refueling Facilities with Examples 

By 2009 we will validate hydrogen vehicles with greater than 250-mile range, 2,000-hour fuel 

cell durability, and $3/gge hydrogen production cost (based on volume production). We are 

identifying the current status of the technology and tracking its evolution over the five-year 

project duration, particularly between the first- and second-generation FCVs. NREL’s role in 

this project is to provide maximum value for DOE and industry from the data produced by this 

“learning demonstration.” We seek to gain knowledge about the progress toward the technical 

targets, and provide that data to the Hydrogen Fuel Cells and Infrastructure Technologies 

(HFCIT) research and development (R&D) activities. This information will allow the program 

to move more quickly toward cost-effective, reliable hydrogen FCVs and supporting refueling 

infrastructure. 

1.2 Approach 

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

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

DaimlerChrysler/BP, Ford/BP, and GM/Shell. We are receiving raw technical data from both 

the hydrogen vehicles and refueling infrastructure that allows us to perform unique and valuable 

analyses across all four teams. Our primary objectives are to feed the current technical 

challenges and opportunities back into the DOE Hydrogen R&D 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) 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). To ensure value is fed back to the hydrogen community, we 

publish composite data products 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 composite data products are conceived as additional trends and results of interest are 

Hydrogen and Gasoline Station

Washington, DC Mobile Refueler

Sacramento, CA 

Steam Methane Reforming

Oakland, CA 

DTE/BP Power Park 

Southfield, MI 

Delivered 

Compressed 

H2

Natural Gas 

On-Site 

Reforming

Delivered 

Liquid H2 

Electrolysis 

 2
identified. We also provide our detailed analytical results (not public) on each individual 

company’s data back to them to maximize the industry benefit from NREL’s analysis work and 

obtain feedback on our methodologies. 

On-Road Data Received -- Running Totals

40095

149019

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

Sep-04Dec-04

Mar-05

Jun-05

Sep-05

Dec-05

Mar-06

Jun-06

Sep-06

Dec-06

Mar-07

Jun-07

Sep-07

MB of Data

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

# Trips

Figure 3: Process Flow for Hydrogen Secure Data Center Analysis and Results, Overlaid on Top of 

Quantity of Data Received at HSDC 

1.3 Key Analysis Accomplishments in FY 2007 

• Created and published 41 new or updated composite data products (the fourth such set of 

public results) representing results from analyzing almost two years of Learning 

Demonstration data. The results will be presented publicly at the Fuel Cell Seminar, 

ZERO REGIO, and EVS-23. 

• Created a new NREL Web page at http://www.nrel.gov/hydrogen/cdp_topic.html to 

allow direct public access to the latest composite data products organized by topic, date, 

and CDP number. This also allowed the results to be indexed directly by search engines. 

• Made major improvements to NREL’s Fleet Analysis Toolkit (FAT) for automatically 

processing and analyzing every vehicle trip file and presenting the results graphically in 

an interactive manner. 

MB of data

# trips

Composite 

Data 

Products

Through August 2007: 

>149,000 individual 

vehicle trips 

40 GB of on-road data 

NREL

HSDC

Detailed 

Data 

Products

 3
• Received and processed a total of 149,000 individual vehicle trips, amounting to over 40 

GB of data, since project inception. 

• Created a new MATLAB analysis program to analyze dominant factors affecting fuel cell 

degradation, including a new graphical user interface for viewing the results in an 

interactive way. 

• Further developed the collaborative technical relationship with all four industry teams by 

giving presentations to each team, including detailed results from NREL’s analysis of 

their vehicle and infrastructure data. 

2 Results 

The results discussed here came from analyzing over two years of vehicle and infrastructure data 

(through June, 2007), resulting in a total of 41 new or updated composite data products to be 

presented at technical conferences. To accomplish this, our in-house analysis tool, FAT, 

continued to undergo improvements and revisions. Since there are now so many technical 

results from the project, they cannot normally all be discussed during brief 15-20 minute 

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

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

results. This web site will make current and archived composite data products available to the 

public. The most recent results are scheduled to be presented publicly at the Fuel Cell Seminar 

(10/07), ZERO REGIO International Demonstration Workshop (11/07), and the EVS-23 

conference in California (12/07) as the set of data called “Fall 2007 Results”. In order to focus 

on high-level results and conclusions, this report will discuss the results in bullet form, organized 

by technical topic. The last section includes all of the composite data products referenced. 

 4
2.1 Vehicle Results 

• Fuel Cell Efficiency: Researchers measured fuel cell system efficiency from select 

vehicles on a vehicle chassis dynamometer at several steady-state points of operation. 

DOE’s technical target for net system efficiency at 1⁄4-power is 60%. Data from the four 

Learning Demonstration teams showed a range of net system efficiency from 52.5% to 

58.1% (Figure 4), which is very close to the target. These results have not changed in the 

last year, but we will use baseline testing to evaluate the efficiency of the secondgeneration systems as soon as they are introduced in the next year. 

• Fuel Cell Operating Points: Recent work included an analysis of the amount of time 

each fleet spent operating their fuel cells within various ranges of power levels. Because 

we found that fuel cells were operated for such a large percentage of time within the 0% 

to 5% maximum power range, we chose to use unequal bins in order to present the 

results. This prevents the values at the higher powers from being washed out by an 

otherwise large scale. Figure 5 shows these results, with the 20%-40% bin including the 

1⁄4 power point previously discussed as having a high efficiency. What this graph shows 

is that the 1⁄4 power point is important relative to power points higher than 40%, but also 

that the region at <20% power is also extremely important in establishing an overall high 

efficiency for an automotive system on-road. It also suggests that implementing idle-off 

for the fuel cell system could substantially reduce energy consumption, as it has done 

with most of today’s gasoline-electric hybrids. 

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

drive-cycle tests (Figure 6) on a chassis dynamometer using draft SAE J2572 (left blue 

bar, representing the range of four points, one from each original equipment manufacturer 

[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 blue bar). 

This resulted in an adjusted fuel-economy range of 42 to 56.5 miles/kg hydrogen for the 

four teams. As with all vehicles sold today, including gasoline hybrids, actual on-road 

fuel economy is slightly lower than this rated fuel economy (right blue bar). The on-road 

fuel economy has improved slightly over the last six months as the usage pattern has 

evolved; it now spans the range of 30 miles/kg H2 to almost 50 miles/kg H2. Note that 

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. 

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

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

vehicle (Figure 7). Using the EPA-adjusted fuel economy resulted in a range from just 

over 100 miles up to 190 miles from the four teams. The second-generation vehicles will 

strive to push this range up to 250 miles to reach the 2009 DOE target. Note that two 

other composite data products relating to range were also generated. Figure 8 shows a 

histogram of the distance vehicles actually traveled between refuelings as a percentage of 

each vehicle’s dyno range. This shows that the majority of the vehicles (80%) travel less 

than 50% of the dyno range between refuelings. This is due to several factors, but the 

dominant ones are limited H2 infrastructure, fear of running out of fuel, and actual onroad fuel economy being lower than the dynamometer fuel economy, as has already been 

 5
discussed. Figure 9 shows the on-road range of the four teams (green bar) as a 

percentage of their dyno range. The spread of this on-road range has decreased 

significantly in the last six months. There is the potential for a greater range from the 

second-generation vehicles due to higher H2 storage pressure (700 bar) and more 

vehicles that may be designed with storage system limitations in mind. Progress on H2 

storage will be reported after second-generation vehicles are introduced. 

• 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 one year ago 

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. We then compared these results to the firstgeneration target of 1,000 hours for 2006. In the past year, many more hours have been 

accumulated on the fuel cell stacks, and the range of fleet averages is ~200-600 hours, 

with the range of fleet maximums spanning ~300-900 hours. Therefore, the amount of 

extrapolation we have to make, using the slope of the voltage degradation method 

(mV/hour times the 10% voltage drop target), continues to decrease. The projected times 

to 10% fuel cell stack voltage degradation from the four teams had an average of more 

than 800 hours with a high projection of more than 1,600 hours from one team, straddling 

the 1,000-hour DOE target (Figure 10). We anticipate that in the next few months one of 

the teams will be first in the world to reach 1,000 hours of fuel cell system operation 

(without stack repair) in real-world operation on a light-duty passenger vehicle. 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” failure modes 

such as membrane failure. The second-generation stacks introduced in this project 

beginning in late 2007 will be compared to the 2,000-hour target for 2009. 

• Factors Affecting Fuel Cell Durability: We have initiated a multivariate analysis to 

determine the dominant factors that are affecting the rates of degradation. We started out 

by creating a database of all of the Learning Demo stacks and various performance 

attributes. Each individual stack was examined for the hours of data accumulated to date, 

amount of time in non-DOE vehicles before data was received, 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: 

o Average degradation rate (key dependent variable) 

o Region of operation (% of time in each) 

o Temperature (% of time in three bins of cold, moderate, and hot) 

o Specific refueling stations used 

o Average number of stack starts/hour 

o Time between trips (to get at cold start impact) 

o Trip length 

 6
o Power levels (% of time in several power bins) 

o Idle time. 

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 11). The trends were not strong, with only 

about 39% of the variance able to be explained by the first two groupings of variables. 

The (+) indicates the variable’s directional relation to high decay rate and a (-) indicates 

an inverse relation. Next we looked at each team’s data individually and performed the 

same PLS analysis (Figure 12). The connection between voltage degradation rate and the 

variables improved significantly, and was able to explain between 61% and 76% of the 

variance in voltage degradation. It is interesting to note that some teams’ degradation 

was influenced by two to three key variables, while others had a more complex influence 

from four to five variables. This analysis effort is not complete, and NREL will work 

closely with each team to carefully examine the inputs and outputs from this analysis and 

see if there are valuable lessons that can be fed back into the companies’ research as well 

as into DOE’s R&D program. 

• Time of Day Vehicles Are Driven: Many questions have arisen about whether the 

Learning Demonstration vehicles are really being used like conventional vehicles, or 

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

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

week the trips were occurring on. Figure 13 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 red diamonds to show the national statistics based on the 2001 

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 to 6 p.m. when the average person (nationally) is likely either picking up kids 

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. However, overall the percentage of 

trips taken between 6 a.m. and 6 p.m. matches extremely closely to the national statistics 

(80.0% vs. 80.1%). Nighttime driving behavior also matches closely with the national 

statistics (Figure 14). 

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

the Learning Demo FCVs and compared this with the national statistics. Figure 15 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 throughout the week (including 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 

doesn’t 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 captured in these vehicles’ duty cycles. 

 7
• Length of Trips: We also examined the length of Learning Demonstration driving trips 

and compared that to the national statistics. Figure 16 shows that the Learning 

Demonstration fleet (green curve) has a sharp peak with almost 1⁄2 the trips being shorter 

than two miles. 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. 

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

of the real-world data. We will also focus additional time on making sure that there are 

not a large number of bad data files (with essentially no data in them) that could be 

unduly influencing these trip distance results. 

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

In accordance with DOE’s safety definitions, there have been no safety incidents or near 

misses involving the vehicles; they have all been non-events. There was previously an 

issue with properly setting thresholds for triggering onboard alarms from hydrogen 

sensors; this has been resolved by the company involved, and Figure 17 shows the 

updated number of vehicle safety reports by quarter. 

• Other Vehicle Metrics: There have been several other vehicle-related composite data 

products that will be briefly mentioned here. Figure 18 shows the range of ambient 

temperature during vehicle operation spanning from 1°F-123°F, slightly lower on the 

cold end of the spectrum than previously reported. So fuel cell vehicles are currently able 

to operate in extreme temperature conditions, but second-generation vehicle tests will 

determine their ability to also start from sub-freezing temperatures. Figure 19 shows the 

distribution of vehicle operating hours, showing a median of about 400-500 hours. 

Similarly, with vehicle miles traveled (shown in Figure 20), the peak number of vehicles 

occurs at 7,500 – 10,000 miles. The total number of vehicle miles traveled through June 

2007 is 821,518, and Figure 21 shows that after the first few quarters, mileage 

accumulation has been relatively linear. Figure 22 tracks the total number of Learning 

Demonstration vehicles deployed by quarter and the on-board hydrogen storage systems 

that they use. 

 8
2.2 Infrastructure Results 

• 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 23. 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. This result has not changed significantly 

in the last six months. 

• 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 sulfur, and are shown 

in Figure 24. One key finding was that reported values are, in general, close to the SAE 

J2719 target values. Previously, for total sulfur, all of the data were reported at the 

detection limits of the gas analysis hardware used, but we have now received one sulfur 

data point that is not detection limited (solid red triangles represent data points that are 

not detection limited). While the target for sulfur is 4 parts per billion (ppb), results 

ranged from 3-70 ppb. Therefore, either new cost-effective techniques to get real 

measurements at such low concentrations should be developed, or the target should be 

raised to something that can be measured with confidence. 

• H2 Infrastructure Maintenance: An evaluation of all of the maintenance required on 

refueling station equipment found that roughly 1⁄2 of all labor hours were unplanned, 

accounting for 60% of the maintenance events (Figure 25). Even while some stations 

have gotten past most startup growing pains and issues, new stations continue to be 

installed and so the spread between planned and unplanned maintenance events has not 

changed much in the last six months. 

• Infrastructure Safety: With respect to hydrogen refueling infrastructure, there has only 

been one event that was classified as an incident. It involved a piece of equipment that 

was incorrectly installed and led to the release of hydrogen from the station’s storage 

tanks into the atmosphere. There were no injuries and no damage except for the piece of 

equipment involved. At a less severe level (see Figure 26), there were eight events 

categorized as near-misses and 91 non-events (primarily alarms-only and equipment 

malfunctions). All but one of the near-misses involved a minor release of hydrogen with 

no ignition. Figure 27 shows that no single primary factor led to the majority of 

infrastructure safety reports, but the following three categories made up over 60 of them: 

calibration/settings or software controls, environment (weather, power disruption, other), 

and inadequate or non-working equipment. Figure 28 shows that the number of 

refuelings normalized by the number of safety reports per quarter had improved by a 

factor of 10 since the beginning of the project, but then dipped down to 60-80 as new 

stations came online. Figure 29 shows that no serious (incident or near-miss) reports 

have occurred in the last three reporting quarters. 

• Vehicle Refueling Rates: Hydrogen vehicle refueling needs to be as similar as possible to 

conventional vehicle refueling to allow an easier commercial market introduction. Over 

6,300 refueling events have been analyzed to date, and the refueling amount, time, and 

rate have been quantified. The average time to refuel was 3.66 minutes with 85% of the 

 9
refueling events taking less than 5 minutes (Figure 30). The average amount per fill was 

2.21 kg, reflecting both the limited storage capacity of these vehicles (~4 kg max) and 

peoples’ comfort level with letting the fuel gauge get close to empty (see Figure 31 for 

the shape of the distributions). This will be shown in a separate analysis. DOE’s target 

refueling rate is 1 kg/minute, and these Learning Demo results indicate an average of 

0.76 kg/min, with 23% of the refueling events exceeding 1 kg/minute (Figure 32). 

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 highpressure hydrogen onboard to provide adequate range, or finding alternate advanced 

hydrogen storage materials that can replace the need for high-pressure tanks. See Figure 

33, Figure 34, and Figure 35 for the status of first-generation storage tanks validated, 

which have not changed since the project was started. 

• Communication vs. Non-Communication Fills: 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. Figure 36 shows two curves: the red 

curve is a spline fit to the normalized histogram for non-communication fills while the 

blue curve represents the communication fills. There is a group of vehicle/station 

combinations still doing non-communication fills at the slower rate of ~0.2 kg/min. 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. 

There is also a second peak representing vehicles performing non-communication fills at 

higher than 1 kg/min, at around 1.2 kg/min (higher than DOE’s 2006 target). NREL will 

seek to understand what protocols some of the non-communication fills are following that 

allow them to reach such a high fill rate. Looking at communication fills (blue curve) we 

see that while the peak is at around 0.7 kg/min, a large percentage of the communication 

fills are higher than 1 kg/min (more than for non-communication fills). In particular, 

there is a fairly flat and significant number of communication fills at between 1.2 and 1.7 

kg/min. So in summary, while communication fills definitely appear to be able to refuel 

at a higher rate than non-communication, the bulk of data gathered to date actually show 

the peak for communication fills being lower than the peak for non-communication fills. 

This will be followed closely as more data are gathered. 

• Level in Fuel Tank at Which 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 for fear 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 37

shows the results from 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 

1⁄4 full, and covers 14% of the refuelings. While some drivers are 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 which indicates the median tank level at fill (1⁄2 above, 1⁄2 below), 

 10
which is a little above 3⁄8 of a tank (40% of full). Figure 38 shows the collection of 

medians for each of the 77 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 refueling more than half of the time with greater than a half-full tank. 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 fuel cell vehicles 

differently than their conventional vehicles. 

• Time of Day When People Refuel: We also looked at the time of day people refueled, in 

order to understand the usage patterns at the hydrogen refueling stations and 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 

really matter. Instead, the station operator must simply ensure that the next tanker comes 

before he runs out. For today’s hydrogen fuels, 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 (on-site production) with the demand. 

Figure 39 shows a radial histogram of the time of day Learning Demo vehicles were 

refueled between 6 a.m. and 6 p.m., with Figure 40 showing the remainder of the time 

between 6 p.m. and 6 a.m. We found that 86% of the fills occurred between 6 a.m. and 6 

p.m., with 14% being done at night. The distribution is relatively uniform with steady 

usage between 8 a.m. and 4 p.m., and a mild peak at lunchtime with 9% occurring then. 

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 41) and found that the Learning Demonstration vehicles are primarily refueled 

Monday through Friday, with very few vehicles refueled on the weekend. This is 

consistent with the days of the week that people are driving the vehicles most. 

• Other Infrastructure Metrics: The amount of hydrogen produced or dispensed has also 

been tracked by quarter (blue diamonds) with the number of stations shown on the same 

graph (green squares) in Figure 42. Note that the amount of hydrogen produced is not the 

same as the amount dispensed because the project includes a power park at which 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. As 

discussed in Figure 2, there are four major types of hydrogen refueling stations being 

demonstrated (shown in Figure 43) and the rate of introduction of these stations is shown 

in Figure 44. 

 11
2.3 Conclusions and Future Directions 

NREL has now analyzed data from over two years of the 5-year project with 77 vehicles now in 

fleet operation, 14 project refueling stations in use, and no major safety problems encountered. 

We’ve analyzed data from 149,000 individual vehicle trips covering 821,000 miles traveled and 

30,000 kg H2 produced or dispensed. Last fall we supported a September 2006 DOE MYPP 

milestone to evaluate on-road fuel cell durability by analyzing voltage degradation and 

comparing the results to the 1,000-hour target. Those results have now been updated with 

another year of on-road data, and include an individual team-average high of over 1,600 hours 

with the 4-team average over 800 hours. To answer the question of what is causing the stacks to 

gradually degrade, NREL initiated work to characterize how each stack is used and then 

performed multivariate analysis on this dataset to examine dominant variables affecting stack 

voltage degradation rate. Early results indicate that trends across all four teams may be hard to 

track, but that individual results for each team should be useful to the teams individually and for 

feeding back trends into the R&D program. We’ve analyzed fuel cell system efficiency at 1⁄4-

power and compared it to the DOE target of 60%; system efficiency results from the four teams 

ranged between 52.5% and 58.1%. Using new data on communication vs. non-communication 

fills, we found that while communication fills demonstrated a higher rate of fill than noncommunication, the bulk of the communication fills were actually slower than the noncommunications fills. We also examined refueling and driving behavior, and found the Learning 

Demonstration fleet to be representative of national statistics with the exception of fewer late 

afternoon and weekend trips, and an abundance of short trips. Finally, we’ve now published a 

total of 41 composite data products to date and made them directly accessible to the public from 

our H2 Technology Validation Web site. 

In the future, we will further explore the correlations of real-world factors influencing fuel cell 

degradation and strive to separate their interwoven dependencies. We will semi-annually 

(spring/fall) compare technical progress to program objectives and targets and provide results to 

the public through participation at technical conferences and writing reports such as this one. 

Specifically, we will create new and updated composite data products based on data through 

December 2007, and prepare those new results for publication at the NHA as the “Spring 2008” 

results. For the second-generation vehicles initially introduced this fall and next year, we will 

begin evaluating improvements in fuel cell durability, range, fuel economy, and safety, and 

publish results when there are sufficient second-generation vehicles to mask the companies’ 

identities. As an important part of the project, we will identify opportunities to feed project 

findings back into HFCIT Program R&D activities to maintain the project as a “learning 

demonstration.” 

 12
2.4 Related Publications/Presentations from FY07 

1. Wipke, K., Sprik, S., Kurtz, J., Thomas, H., “Composite Data Products for the Controlled 

Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” Golden, CO: 

National Renewable Energy Laboratory, updated September 2007. (online at 

http://www.nrel.gov/hydrogen/cdp_topic.html). 

2. Wipke, K., Sprik, S., Thomas, H., Welch, C., Kurtz, J., “Learning Demonstration Interim 

Progress Report – Summer 2007,” National Renewable Energy Laboratory Technical 

Report NREL/TP-560-41848, July 2007. 

3. Wipke, K., “Hydrogen Secure Data Center: Procedures to Protect Technical Data 

Submitted under the Controlled Hydrogen Fleet and Infrastructure Demonstration and 

Validation Project,” Golden, CO: National Renewable Energy Laboratory, updated June 

2007. 

4. Wipke, K., Welch, C., Thomas, H., Sprik, S., “Controlled Hydrogen Fleet and 

Infrastructure Analysis,” DOE Annual Merit Review Meeting, Washington, DC, May 

2007. (presentation) 

5. Wipke, K., Welch, C., Thomas, H., Sprik, S., Gronich, S., Garbak, J., Hooker, D., “Fuel 

Cell Vehicle Learning Demonstration: Spring 2007 Results,” NHA Annual Hydrogen 

Meeting and Exposition, San Antonio, TX, March 2007. (presentation) 

6. Wipke, K., Welch, C., Thomas, H., Sprik, S., Gronich, S., Garbak, J., “Controlled 

Hydrogen Fleet and Infrastructure Demonstration and Validation Project: Initial Fuel Cell 

Efficiency and Durability Results,” World Electric Vehicle Association Journal, 

December 2006. (paper) 

7. Wipke, K., Welch, C., Thomas, H., Sprik, S., “Controlled Hydrogen Fleet and 

Infrastructure Analysis Project,” 2006 DOE HFCIT Program Annual Progress Report, 

November 2006. (paper) 

8. Wipke, K., Welch, C., Thomas, H., Sprik, S., Gronich, S., Garbak, J., “Hydrogen Leaning 

Demonstration Project: Fuel Cell Efficiency and Initial Durability,” Fuel Cell Seminar, 

November 2006. (extended abstract and presentation) 

9. Wipke, K., presentation of Learning Demonstration results to FreedomCAR Vehicle 

Systems Analysis Tech Team, July 12, 2006 and Nov. 8, 2006. 

10. Wipke, K., presentation of Learning Demonstration results to FreedomCAR Fuel Cell 

Tech Team, October 18, 2006. 

11. Wipke, K., Welch, C., Thomas, H., Sprik, S., Gronich, S., Garbak, J., “Hydrogen Fleet & 

Infrastructure Demonstration and Validation Project: Fall 2006 Progress Update,” EVS22, Yokohama, Japan, October 2006. (paper and presentation) 

 13
12. Wipke, K., Welch, C., Thomas, H., Sprik, S., Gronich, S., Garbak, J., “Hydrogen Fleet & 

Infrastructure Demonstration and Validation Project: Fall 2006 Progress Update,” CARB 

ZEV Technology Symposium, September 25, 2006. (presentation) 

13. Welch, C., Wipke, K., Thomas, H., Sprik, S., “DOE’s Controlled Hydrogen Fleet and 

Infrastructure Demonstration and Validation Project: Quarterly Validation Assessment 

Reports,” (HSDC papers only) 

o 3Q 2006, December 2006. 

o 4Q 2006, March 2007. 

o 1Q 2007, June 2007. 

o 2Q 2007, September 2007. 

2.5 Acronyms 

CDP composite data product 

FAT Fleet Analysis Toolkit (software tool developed at NREL) 

FCV fuel cell vehicle 

FY fiscal year 

gge gallon of gasoline equivalent 

H2 hydrogen 

HFCIT Hydrogen, Fuel Cells & Infrastructure Technologies (DOE 

program) 

HSDC Hydrogen Secure Data Center (at NREL) 

MYPP Multi-Year Program Plan (DOE document) 

NHA National Hydrogen Association 

NREL National Renewable Energy Laboratory 

R&D research and development 

 14
2.6 Composite Data Products Referenced in Previous Discussion 

0

10

20

30

40

50

60

70

All OEMs

Efficiency (%) 

Fuel Cell System1 Efficiency2 at ~25% Net Power.

DOE Target

Created: Aug-29-06 4:09 PM

1

 Gross stack power minus fuel cell system auxiliaries, per DRAFT SAEJ2615.

2

 Ratio of DC output energy to the lower heating value of the input fuel (hydrogen).

Excludes power electronics and electric drive.

Figure 4: Fuel Cell System Efficiency at ~25% Net Power 

0-5% Pwr 5-10% Pwr 10-20% Pwr 20-40% Pwr 40-60% Pwr 60-80% Pwr 80-100% Pwr >100% Pwr 0

5

10

15

20

25

30

35

40

45

50

% Time at Power Level

% Fuel Cell Power (Gross) of Max

On-Road % Time at Power Levels: DOE Fleet

Created: Sep-10-07 4:31 PM

Figure 5: Fuel Cell Operating Powers 

 15
Dyno (1) Window-Sticker (2) On-Road (3)(4) 0

10

20

30

40

50

60

70

80

Fuel Economy (miles/kg H 2

)

Fuel Economy

Created: Aug-23-07 2:48 PM

(3) Excludes trips < 1 mile. One data point for on-road fleet average of each make/model.

(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).

(4) Calculated from on-road fuel cell stack current or mass flow readings.

Figure 6: Learning Demonstration Fuel Cell Vehicle Fuel Economy 

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

Created: Aug-23-07 2:47 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.

Figure 7: Learning Demonstration Fuel Cell Vehicle Range 

 16
0 10 20 30 40 50 60 70 80 90 100 0

1

2

3

4

5

6

7

8

9

10

11

12

Range Histogram: All OEMs

Percentage of chassis dyno range1

 b/w refuelings

Percentage of Refuelings

0 10 20 30 40 50 60 70 80 90 1000

25

50

75

100

Cumulative Percentage

Created: Aug-23-07 3:24 PM

Total refuelings2 = 7966

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.

Figure 8: Percentage of Theoretical Range Traveled Between Refuelings 

0 10 20 30 40 50 60 70 80 90 100

Vehicle Range Factors

Percentage of chassis dyno range1

.

All OEMs

Window-Sticker 2On-Road 3Dyno 1

Created: Aug-23-07 12:39 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).

Figure 9: Effective Vehicle Range 

 17
0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2006 Target

2009 Target

Actual Operating Hours Accumulated To-Date Projected Hours to 10% Degradation

Max Hrs Accumulated (1)(2) Avg Hrs Accumulated (1)(3) Projection to 10% Degradation (4)(5)

Time (Hours)

DOE Learning Demonstration Fuel Cell Stack Durability:

Based on Data Through 2007 Q2

Max Projection

Avg Projection

Created: Aug-23-07 10:42 AM

(1) Range bars created using one data point for each OEM.

(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 green bar represents an engineering judgment of the uncertainty due to data and methodology limitations. Projections will change

 as additional data are accumulated.

Figure 10: Fuel Stack Hours Accumulated and Projected Hours to 10% Voltage Degradation 

Power levels (low) (+)

High decay rate2

Idle time (+)

Correlation to 

Decay Rate Data

~10% Decay rate variance explained by a 

combination of the data variables below1

Trip length (-)

Time between trips (+)

Power levels (high & average) (+)

High decay rate2

Starts per hour (+)

Correlation to 

Decay Rate Data

~29% Decay rate variance explained by a 

combination of the data variables below1

Power levels (low) (+)

High decay rate2

Idle time (+)

Correlation to 

Decay Rate Data

~10% Decay rate variance explained by a 

combination of the data variables below1

Trip length (-)

Time between trips (+)

Power levels (high & average) (+)

High decay rate2

Starts per hour (+)

Correlation to 

Decay Rate Data

~29% Decay rate variance explained by a 

combination of the data variables below1

1. Findings based on a Learning Demonstration Fleet, Partial Least Squares (PLS) regression model. Approximately 39% decay rate

variance explained by the model.

2. As part of the variable combination, a (+) indicates a directional relation to high decay rate and a (-) indicates an inverse relation.

Created: Aug-31-07 9:00 AM

Figure 11: Primary Factors Affecting Learning Demo Fleet Fuel Cell Degradation 

 18
Team 4 Team 4

Team 3 Team 3 Team 1 Team 1

Team 2 Team 2

Starts per

Hour

Trip 

Length

Time Between 

Trips

Idle 

Time

Ambient Temperature

Power Levels

1. Results are from partial least squares (PLS) regression analysis of each team’s fleet of vehicles individually

2. First two collections of factors cover ~61%-76% of decay rate variance

Created: Aug-31-07 9:00 AM

Team 4 Team 4

Team 3 Team 3 Team 1 Team 1

Team 2 Team 2

Starts per

Hour

Trip 

Length

Time Between 

Trips

Idle 

Time

Ambient Temperature

Power Levels

1. Results are from partial least squares (PLS) regression analysis of each team’s fleet of vehicles individually

2. First two collections of factors cover ~61%-76% of decay rate variance

Created: Aug-31-07 9:00 AM

Figure 12: Primary Factors Affecting Learning Demo Team Fuel Cell Degradation 

Driving Start Time - Day: DOE Fleet

8%

3

12

9

6

2001 NHTS Data; Only Car, Truck, Van, & SUV trips included in data set shown here

Created: Sep-10-07 3:11 PM

Total Driving3 % of driving trips b/t 6 AM & 6 PM: 80.0% Events = 103009

1. Driving trips between 6 AM & 6 PM

2. The outer arc is set at 10 % 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: 80.1%

Source: http://nhts.ornl.gov/download.shtml#2001, ASCII.csv

Figure 13: Driving Start Time – Day 

 19
Driving Start Time - Night: DOE Fleet

4%

3

12

9

6

2001 NHTS Data; Only Car, Truck, Van, & SUV trips included in data set shown here

Created: Sep-10-07 3:11 PM

Total Driving3 % of driving trips b/t 6 PM & 6 AM: 20.0% Events = 103009

1. Driving trips between 6 PM & 6 AM

2. The outer arc is set at 10 % 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: 19.8%

Source: http://nhts.ornl.gov/download.shtml#2001, ASCII.csv

Figure 14: Driving Start Time -- Night 

Sunday Monday Tuesday Wednesday Thursday Friday Saturday 0

5

10

15

20

Driving Trips by Day of Week: DOE Fleet

% of Driving Trips in a Day

Day

2001 NHTS Data; Only Car, Truck, Van, & SUV trips included in data set shown here Created: Sep-10-07 3:11 PM

Source: http://nhts.ornl.gov/download.shtml#2001, ASCII.csv

Figure 15: Driving by Day of Week 

 20
0 5 10 15 20 25 30 0

5

10

15

20

25

30

35

40

45

50

% Trips within a mileage range

Trip Length (miles)

Trip Length (in miles): DOE Fleet

DOE Fleet

NHTS Data

Created: Sep-10-07 4:31 PM 2001 NHTS Data; Only Car, Truck, Van, & SUV day trips included in data set shown here

Source: http://nhts.ornl.gov/download.shtml#2001, ASCII.csv

Figure 16: Trip Length 

Safety Reports - Vehicle Operation

0

1

2

3

2005 Q2

2005 Q3

2005 Q4

2006 Q1

2006 Q2

2006 Q3

2006 Q4

2007 Q1

2007 Q2

Number of Reports

H2 Leak - During Fueling

H2 Alarm - Stack

H2 Alarm - Fuel System

H2 Alarm - Passenger Compartment

Created: 8/23/07 7:51PM

Figure 17: Safety Reports – Vehicles 

 21
-30

-20

-10

0

10

20

30

40

50

60

1.4oF

122.9oF

Degrees Celsius

Ambient Temperature During Operation

All OEMs

Created: Aug-23-07 9:33 AM

Figure 18: Range of Ambient Temperature during Vehicle Operation 

Vehicle Hours: All OEMs Combined

0

2

4

6

8

10

12

14

0-100

100-200

200-300

300-400

400-500

500-600

600-700

700-800

800-900

>900

Total Vehicle Hours

Number of Vehicles

Through 2007 Q2

Created: Aug-23-07

Total Vehicle Hours = 39,748

Figure 19: Vehicle Operating Hours 

 22
Vehicle Miles: All OEMs Combined

0

2

4

6

8

10

12

0-2500

2500-5000

5000-7500

7500-10000

10000-12500

12500-15000

15000-17500

17500-20000

20000-22500

>22500

Total Vehicle Miles

Number of Vehicles

Total Miles Traveled = 821,518

Through 2007 Q2

Created: Aug-23-07

Figure 20: Number Vehicles vs. Miles Traveled 

Cumulative Vehicle Miles Traveled: All OEMs

-

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

2005Q22005Q32005Q42006Q12006Q2

2006Q32006Q42007Q12007Q2

Vehicle Miles Traveled

Created: Aug-23-07

Figure 21: Cumulative Vehicle Miles Traveled 

 23
On-Board Hydrogen Storage Methods

-

10

20

30

40

50

60

70

80

90

2005Q2 2005Q3 2005Q4 2006Q1 2006Q2 2006Q3 2006Q4 2007Q1 2007Q2

# of Vehicles (All Teams)

Liquid H2

10,000 psi tanks

5,000 psi tanks

Created Aug-28-2007 9:29PM

Figure 22: Vehicle Hydrogen Storage Technologies 

99.73

99.74

99.75

99.76

99.77

99.78

99.79

99.8

99.81

99.82

99.83

99.84

99.85

99.86

99.87

99.88

99.89

99.9

99.91

99.92

99.93

99.94

99.95

99.96

99.97

99.98

99.99

100

Hydrogen Fuel Quality Index (%)

Hydrogen Fuel Quality Index Sampled from Stations(1)

Data Range

Data

SAE J2719

Created: Aug-23-07 11:03 AM

(1) Includes sampling from both electrolysis and reforming

Figure 23: Hydrogen Quality Index Scatter Plot 

 24
0 1 2 3 4 5 6 7 8 9 10

Particulates 

μg/L

H2

 Impurities

Data Range SAE J2719 Measured Less Than or Equal To (Detection Limited)

0 500 1000 1500 2000 2500 3000

(N2 + He + Ar) 

0 5 10 15 20 25 30 35 40

H20 

Total HC 

O2 

CO2 

CO 

NH3 

μmol/mol (ppm)

0 10 20 30 40 50 60 70 80 90 100

Total S* 

nmol/mol (ppb) Created: Aug-23-07 11:03 AM *Calculated from SO2, COS, H2S, CS2, and Methyl Mercaptan (CH3SH).

Figure 24: Hydrogen Impurities Scatter Plot 

0 20 40 60 80 100 120 140

Adjustment

Check Only

Other

Repair

Replacement

Maintenance: Average Labor Hours Per Station Since Inception

Scheduled

Un-Scheduled

0 5 10 15 20 25

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

Created: Aug-21-07 4:08 PM

Figure 25: Infrastructure Maintenance 

 25
0 10 20 30 40 50 60 70 80 90 100

Non-Event

Near Miss

Incident

Number of Reports

Severity

Total Infrastructure Safety Reports by Severity

and Report Type through 2007 Q2

Alarms Only

Automatic System Shutdown

Electrical Issue

Equipment Malfunction

H2 Release - Minor, NO Ignition

H2 Release - Significant, NO Ignition

Non-H2 Release

System Trouble, not Alarm

Created: Sep-06-07 7:36 AM

Figure 26: Infrastructure Safety Reports by Severity and Report Type 

0 10 20 30 40 50 60 70 80 90 100

Non-Event

Near Miss

Incident

Number of Reports

Severity

Primary Factors of Infrastructure Safety Reports

Through 2007 Q2

Calibration/Settings/ Software Controls

Design Flaw

Environment (Weather, Power Disruption, Other)

Inadequate/ Non-working Equipment

Maintenance Required

Mischief, Vandalism, Sabotage

Not Yet Determined

Operator/Personnel Error

Created: Sep-06-07 7:36 AM

Figure 27: Primary Factors of Infrastructure Safety Reports 

 26
2005Q2 2005Q3 2005Q4 2006Q1 2006Q2 2006Q3 2006Q4 2007Q1 2007Q2 0

2

4

6

8

10

12

14

Reporting Period

Number of Stations

Infrastructure Safety Trend and Online Stations Thru 2007Q2

Number of Online Stations

Avg Refuelings Between Safety Reports

Created: Sep-06-07 7:36 AM

0

20

40

60

80

100

120

140

Number of Refuelings

7

13

34

40

114

125

129

62

82

Figure 28: Average Refuelings between Infrastructure Safety Reports 

2005Q2 2005Q3 2005Q4 2006Q1 2006Q2 2006Q3 2006Q4 2007Q1 2007Q2 0

2

4

6

8

10

12

14

16

18

Reporting Period

Number of Reports

Type of Infrastructure Safety Reports by Quarter Through 2007 Q2

Incident

Near Miss

Non-Event

Stations Online

Avg # Reports/Station

Created: Sep-06-07 7:36 AM

Figure 29: Type of Infrastructure Safety Report by Quarter 

 27
0 2 4 6 8 10 12 14 16 18 20 0

100

200

300

400

500

600

700

800

900

1000

Time (min)

Number of Fueling Events

Histogram of Fueling Times

All Light Duty Through 2007Q2

Average = 3.66

 % <5 = 85

Created: Aug-23-07 1:29 PM

Figure 30: Refueling Times 

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0

50

100

150

200

250

Amount Fueled (kg)

Number of Fueling Events

Histogram of Fueling Amounts

All Light Duty Through 2007Q2

Average = 2.21

Created: Aug-23-07 1:29 PM

Figure 31: Refueling Amounts 

 28
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0

50

100

150

200

250

300

350

400

450

500

Avg Fuel Rate (kg/min)

Number of Fueling Events

Histogram of Fueling Rates

All Light Duty Through 2007Q2

5 minute fill of

5 kg at 350 bar

3 minute fill of

5 kg at 350 bar

Average = 0.76

 % >1 = 23

2006 Tech Val Milestone

2010 MYPP Adv Storage Materials Target

Created: Aug-23-07 1:29 PM

Figure 32: Refueling Rates 

0

2000

4000

6000

8000

10000

12000

All OEMs

Number of cycles

Hydrogen Tank Cycle Life

2015 DOE MYPP Target1

2010 DOE MYPP Target1

2007 DOE MYPP Target1

Created: 23-Feb-2006

1

Some near-term targets have been achieved with compressed and liquid tanks. Emphasis is on advanced materials-based technologies.

Figure 33: Compressed and Liquid Hydrogen Tank Cycle Life 

 29
0

1

2

3

4

5

6

7

8

9

All OEMs

Weight Percent Hydrogen (%)

Weight Percent Hydrogen

2015 DOE MYPP Target1

2010 DOE MYPP Target1

2007 DOE MYPP Target1

Created: 23-Feb-2006

1

Some near-term targets have been achieved with compressed and liquid tanks. Emphasis is on advanced materials-based technologies.

Figure 34: Compressed and Liquid Hydrogen Tank Weight-Percent 

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

All OEMs

Mass H2 per Liter (kg/L)

Mass of Hydrogen Per Liter

2015 DOE MYPP Target1

2010 DOE MYPP Target1

2007 DOE MYPP Target1

Created: 23-Feb-2006

1Emphasis is on advanced materials-based technologies.

Figure 35: Compressed and Liquid Hydrogen Tank Volumetric Capacity 

 30
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Avg Fuel Rate (kg/min)

Number of Events (Normalized)

Histogram of Fueling Rates

Comm vs Non-Comm Fills - All Light Duty Through 2007Q2

5 minute fill of

5 kg at 350 bar

3 minute fill of

5 kg at 350 bar

Comm

Non-Comm

2006 Tech Val Milestone

2010 MYPP Adv Storage Materials Target

Created: Aug-22-07 5:46 PM

Figure 36: Fueling Rates – Communication and Non-Communication Fills 

Tank Levels: DOE Fleet

14%

E F

Created: Sep-10-07 3:14 PM

Total refuelings1 = 10303

1. Some refueling events not recorded/detected due to data noise or incompleteness.

Median Tank Level = 40% at Fill

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.

Figure 37: H2 Tank Level at Refueling 

 31
E F

Tank Level Medians: DOE Fleet, All Vehicles

Created: Sep-10-07 3:14 PM

Total refuelings1 = 10303

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.

Figure 38: Refueling Tank Levels – Medains 

Refueling by Time of Day: DOE Fleet

9%

3

12

9

6

Created: Sep-10-07 3:14 PM

Total Fill3 % of fills b/t 6 AM & 6 PM: 86.0% Events = 9070

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

Figure 39: Refueling by Time of Day 

 32
Refueling by Time of Night: DOE Fleet

5%

3

12

9

6

Created: Sep-10-07 2:33 PM

Total Fill3 % of fills b/t 6 PM & 6 AM: 14.0% Events = 9070

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

Figure 40: Refueling by Time of Night 

Sunday Monday Tuesday Wednesday Thursday Friday Saturday 0

5

10

15

20

Fills by Day of Week: DOE Fleet

% of Fills in a Day

Day

Created: Sep-10-07 3:14 PM

Figure 41: Refueling by Day of Week 

 33
Cumulative Hydrogen Produced or Dispensed 

Through 2007 Q2

0

5

10

15

20

25

30

35

2005 Q2

2005 Q3

2005 Q4

2006 Q1

2006 Q2

2006 Q3

2006 Q4

2007 Q1

2007 Q2

Calendar Quarter

Mass of Hydrogen (kg) 

(thousands)

0

2

4

6

8

10

12

14

16

Cumulative Hydrogen

Number of Stations

Number of Stations

Created 2007-Sep-07

Figure 42: Cumulative Hydrogen Produced or Dispensed 

Infrastructure Hydrogen Production Methods 

0

1

2

3

4

5

Delivered

Compressed H2

Natural Gas On-site

Reforming

Electrolysis Delivered Liquid H2

Production Technology

# of Stations

Created Aug-23-07

Figure 43: Number and Types of Hydrogen Stations Being Demonstrated 

 34
Online Stations

0

2

4

6

8

10

12

14

16

2005 Q2 2005 Q3 2005 Q4 2006 Q1 2006 Q2 2006 Q3 2006 Q4 2007 Q1 2007 Q2

Reporting Period

Number of Stations

Created Aug-12-07

Figure 44: Number of Stations Online by Quarter 

 35
F1147-E(09/2007) 

REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, 

gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this 

collection of information, including suggestions for reducing the burden, to Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents 

should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a 

currently valid OMB control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ORGANIZATION.

1. REPORT DATE (DD-MM-YYYY)

November 2007 

2. REPORT TYPE

Technical Report 

3. DATES COVERED (From - To)

 

5a. CONTRACT NUMBER

DE-AC36-99-GO10337 

5b. GRANT NUMBER

4. TITLE AND SUBTITLE

Learning Demonstration Progress Report - September 2007 

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

NREL/TP-560-42264 

5e. TASK NUMBER

H2708100 

6. AUTHOR(S)

K. Wipke, S. Sprik, J. Kurtz, and H. Thomas 

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Renewable Energy Laboratory 

1617 Cole Blvd. 

Golden, CO 80401-3393 

8. PERFORMING ORGANIZATION 

REPORT NUMBER

NREL/TP-560-42264 

10. SPONSOR/MONITOR'S ACRONYM(S)

NREL 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

11. SPONSORING/MONITORING 

AGENCY REPORT NUMBER

12. DISTRIBUTION AVAILABILITY STATEMENT

National Technical Information Service 

U.S. Department of Commerce 

5285 Port Royal Road 

Springfield, VA 22161 

13. SUPPLEMENTARY NOTES

14. ABSTRACT (Maximum 200 Words)

This report documents the key results from the DOE Controlled Hydrogen Fleet and Infrastructure Validation and 

Demonstration project. This project is also referred to as the fuel cell vehicle and infrastructure learning 

demonstration. 

15. SUBJECT TERMS

fuel cell demonstration; vehicle demonstration; hydrogen infrastructure; hydrogen vehicle, fuel cell 

16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON 

a. REPORT 

Unclassified 

b. ABSTRACT 

Unclassified

c. THIS PAGE 

Unclassified

17. LIMITATION 

OF ABSTRACT

UL 

18. NUMBER 

OF PAGES 

19b. TELEPHONE NUMBER (Include area code)

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18