Model Framework

Majority Buyers 

Sales Distribution

40

35

30

25

20

15

10

5

0

0 100 50 150 200 250

Viability Index

ICE Power (kW)

Model 

Estimate -

Modified

Actual 2004

Compact 

Car Sales

Hydrogen Storage Inputs

Design Variables 

and Settings

Results

to Record

Vehicle Inputs Run Drive Cycles

Vehicle Viability

Estimation

• Modifi ed weighting 

factors to refl ect

actual market trends

• Attributes considered

 - Capital cost

- Fuel cost

 - Acceleration

- Range

Experiment Design and Assumptions

1 2009 Toyota Camry

2

 EPA Combined based on post-2008 calculations

3

 Based on 2015 hydrogen storage and fuel cell cost

targets as well as current high volume motor, power

electronics and battery cost estimates

Assumptions

Attribute Units Conventional

Vehicle1

Fuel Cell

Vehicle

Fuel converter power kW 126 125

Electric motor power kW - 100

Battery power kW - -

Battery energy kWh - -

Glider mass kg 914 914

Frontal area m2 2.16 2.16

Coeffi cient of drag - 0.28 0.28

Wheel radius m 0.282 0.282

Tire rolling resistance - 0.008 0.008

Fuel economy2 mpgge 25.9 49.9

Range miles 479 304

0-60 mph time sec 8.6 8.7

Capital cost3 $ 19,395 27,419

Part 1: Target sensitivities for fi xed component sizes

Gravimetric

Capacity

(kWh/kg)

Transient

Response

(sec)

Cost

($/kWh)

Full Flow 

Rate

(g/s)/kW

Minimum 0.5 1 $1.00 0.0025

Maximum 3.5 6 $12.00 0.025

Levels 7 612 10

Part 2: Target sensitivities capturing 

component sizing interactions

Gravimetric

Capacity

(kWh/kg)

Fuel Cell

Peak Power 

(kW)

Motor 

Peak Power 

(kW)

ESS Peak

Power

(kW)

ESS

Energy

(kWh)

Minimum 0.5 25 25 20 0

Maximum 5 175 200 80 3

Levels 10 4 8 74

Design of Experiments

Technical Targets

DOE Onboard Hydrogen Storage 

System Targets Considered

Storage Parameter Units 2010 2015

System gravimetric capacity kWh/kg 1.5 1.8

Storage system cost $/kWh TBD TBD

Peak discharge rate (g/s)/kW 0.02 0.02

Transient response (10% - 90%) sec 0.75 0.75

Fuel Cell Power System Targets Considered: 

Characteristic Units 2005 2010 2015

Energy effi ciency @ 25% of 

rated power % 60 60 60

Energy effi ciency @ rated power % 50 50 50

Specifi c power W/kg 500 650 650

Cost $/kW 100 35 25

Transient response (10% - 90%) sec 2 1 1

Source: www1.eere.energy.gov/hydrogenandfuelcells/storage/pdfs/targets_onboard_hydro_storage_explanation.pdf

Source: www1.eere.energy.gov/vehiclesandfuels/resources/fcvt_plans_roadmaps.html

Referenced

previous 2015

target of 

$2/kWh for

this analysis

Objectives

• Demonstrate an approach to evaluate hydrogen storage system characteristic trade-off s

across several vehicle confi gurations

• Estimate the sensitivity of hydrogen 

storage system improvements on 

vehicle viability

Background

Hydrogen Storage Engineering Center of Excellence (HSECoE)

• Under Department of Energy (DOE) Fuel Cell Technologies Program within the Offi ce of Energy Effi ciency and Renewable Energy

• Complement the three materials-based hydrogen storage CoEs

• Research and develop onboard vehicular storage systems and

components that will reach DOE targets while meeting vehicle

related packaging, safety, cost and performance requirements

Objectives and Approach

Approach

• Use an integrated system modeling 

approach by combining vehicle, cost

and viability models to evaluate overall 

system performance

• Evaluate numerous vehicle combinations to

take advantage of unique characteristics of 

individual storage systems

H2

HSSIM

Hydrogen Storage SIMulator

stems

HSS

The authors thank the U.S. Department of Energy’s Fuel Cell Technologies Program within the Offi ce of Energy Effi ciency and Renewable Energy for funding and support. This presentation does not contain any proprietary, confi dential, or otherwise restricted information.

Presented at the 18th World Hydrogen Energy Conference, 16-21 May 2010, Essen, Germany • NREL/PO-540-48120

NREL is a national laboratory of the U.S. Department of Energy, Offi ce of Energy Effi ciency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

• Estimated the sensitivity of hydrogen storage system

improvements on vehicle viability

• Decreasing fuel cell power and increasing 

battery power can help preserve vehicle

viability with slow transient response

storage systems

• Using the “Most Viable” and “Best NPC” 

approaches provides similar results

H2

Conclusions

2010 Target:

1.5 kWh/kg

(0.045 wt%)

Transient Response

35%

30%

25%

20%

15%

10%

5%

0%

0 2 1 3456 7

Viability Index

Seconds

2010/2015 Target:

0.75 sec

Gravimetric Capacity

35%

30%

25%

20%

15%

10%

5%

0%

0.0 1 .5 1 .00 .5 2.0 2.5 3 .0 4 .53 .0

Viability Index

kWh/(kg system)

Storage System Cost Sweep

35%

30%

25%

20%

15%

10%

5%

0%

0 $2 $4 $6 $8 $10 $12 $14

Viability Index

Dollars per kWh ($/kWh)

Previous 2015 Target:

$2/kWh

Previous 2010 Target:

$4/kWh

Storage System Full

Flow Rate Sweep

35%

30%

25%

20%

15%

10%

5%

0%

0.0 1 .5 1 .00 .5 2.0 2.5 3.0 3.5

Viability Index

Storage System Full Flow Rate (g/s)

2010/2015 Target

2.5 g/s

Note: Assumes125 kW

Fuel Cell

2015 Target:

1.8 kWh/kg

(0.055 wt%)

Results

“Part 1” Confi guration

No 

Energy

Storage

Power

(kW)

Power

(kW)

Energy 

(kWh)

Power

(kW)

125 0 0 100

 Fuel economy (mpgge) 50

 Range (miles) 304

0-60 mph time (sec) 8.7

1 Same as “Best NPC FCV confi guration

“Most Viable FCV1”

Confi guration

Power

(kW)

Power

(kW)

Energy 

(kWh)

Power

(kW)

25 80 1 100

 Fuel economy (mpgge) 55

 Range (miles) 337

0-60 mph time (sec) 8.7

Part 2

Part 1

35%

30%

25%

20%

15%

10%

5%

0%

0 2 1 3456 7

Viability Index

Transient Response (sec)

2010/2015 Target:

0.75 sec

Part 1 Most Viable FCV Best NPC FCV

Evaluation of Hydrogen Storage System Characteristics for 

Light-Duty Vehicle Applications

Matthew Thornton, Kristin Day, Aaron Brooker – National Renewable Energy Laboratory

NREL is a national laboratory of the U. S. Department of Energy, Offi ce of Energy Effi ciency

and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.