SCHATZENERGYRESEARCHCENTER

Comparative Performance of Electrolysis Cell Stacks

at the HSU Hydrogen Fueling Station

Meg Harper

Schatz Energy Research CenterHumboldt State University

National Hydrogen Association Annual MeetingMay 4, 2010

© 2010 Schatz Energy Research Center

Chris CapuanoProton Energy Systems

Greg Chapman and Peter Lehman

Schatz Energy Research Center

Outline

• Introduction• Station Overview• New Cell Stack Specifications• Performance Improvements• Conclusions• Questions

Energy in

H2 out

The ExperimentCompare the performance of Proton’s Next Generation cell stack to the originally

installed stack

LHV of H2 ProducedEnergy Consumption of Electrolyzer

Efficiency =

HSU Hydrogen Fueling Station

• Northernmost and only rural station on California’s Hydrogen Highway

• Grand opening was September 4, 2008

SERC Director Peter Lehman cuts the ribbon opening HSU’s station as Congressman Mike Thompson, HSU President Rollin Richmond and SERC engineer and project manager Greg Chapman look on.

Fueling Station & Fleet

Serves two vehicles:• Hydrogen-powered Toyota Prius• Toyota’s Fuel Cell Hybrid Vehicle (FCHV-adv)

Interpretive Sign

The station generates H2 with a Proton electrolyzer, compresses it to 420 bar storage with a PDC compressor, and dispenses it to vehicles at 350 bar with an FTI dispenser.

Electrolyzer

• Proton Systems HOGEN S40 PEM electrolyzer

• 2.3 kg H2 per day

• 99.9995% pure hydrogen

• H2 tested by Atlantic Analytical Lab and found to have no detectable impurities and be suitable for fuel cell vehicles

• 200 psig maximum output pressure

Data Acquisition and Instrumentation

DAQ recorded:• Power to the electrolyzer • Mass flow of hydrogen from the electrolyzer

Manually recorded:• Cell Stack Current using a current shunt attached to a Fluke 73 III multi-meter

• Cell Stack Voltage using a Fluke 45 multi-meter• Cell Stack temperature as measured by the unit’s thermistor in the water circulation system

Hydrogen Water Separator Tank

Hydrogen Gas Dryer

Heat Exchanger Bypass

• Adjustable valves allow water to partially bypass the heat exchanger to control the operating temperature of the cell stack

• System can run at temperatures up to 60 ˚C

• Testing occurred at 34 ˚C and 56 ˚C

Next Generation Cell Stack

• Proton Energy Systems developmental model

• Bipolar plate design which replaces frame, flow-field, and separator plate with a single component

• Reduction from 29 parts to 9 parts per stack

Experimental Results

Results of Cell Stack Performance Tests

Cell Stack

Temp (˚C)

Power (W)

Specific Energy

Consumption (kWh/kg H2)

Efficiency (%)

% Improvement

in Efficiency

Original 34.0 6067 57.3 58.3

New 33.9 5614 53.0 63.9 8.0%

Original 56.8 5620 53.1 62.9

New 56.6 5288 49.9 66.9 6.4%

LHV of H2 ProducedEnergy Consumption of Cell Stack

Efficiency =

Power Use

Error bars = 95% Confidence Interval

Overall Electrolyzer Energy Consumption

MeasuredOriginal(Low Temp)

Measured New (High Temp)

78 kWh/kg 70 kWh/kg

This is a comparison of overall energy consumption of the electrolyzer using the original cell stack operating at normal temperatures to the new cell stack operating at elevated temperatures. The energy use is shown for a measured H2 production rate of 18.0 slm.

Conclusions• The new cell stack is more efficient, improving by

approximately 8.0% at low temperatures and 6.4% at high temperatures.

• Using the new stack at higher temperatures decreases the overall electrolyzer energy consumption by 10%. This still represents a specific energy density of 70 kWh/kg, highlighting the need to improve the entire electrolyzer system.

• The new stack has worked well for three months.• If the HOGEN ran continuously, these efficiency

improvements would save us approximately $800/year in electricity costs. At a larger station these savings would be more substantial.

Many Thanks to Proton Energy Systems and Our

Original Project Sponsors:

Chevron Technology Ventures CalTrans

California Air Resources Board North Coast Unified Air Quality Management

District O&M Industries

HSU

Contact InformationSchatz Energy Research

CenterHumboldt State University

(707) 826-4345serc@humboldt.eduwww.schatzlab.org

Thank you

SCHATZENERGYRESEARCHCENTER Extra Slides for fielding

questions

Hydrogen Water

Separator

Hydrogen Gas Dryer

Measured Hydrogen Output

Hydrogen Water

Separator

Hydrogen Gas Dryer

More Hydrogen Output

Hydrogen Water

Separator

Hydrogen Gas Dryer

Less Hydrogen Output

SCHATZENERGYRESEARCHCENTER

Major Equipment Costs

Equipment Cost (USD)

Electrolyzer $76,600

Compressor $46,600

Storage Tanks $45,100

Dispenser $62,500

Taxes and Shipping

$22,200

Total $253,000

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Total Station Cost

The total cost does not include the cost of 1300 ft2 of land donated by HSU.

Category Cost (USD)Major Equipment $253,000Balance of System $133,000Labor $220,000Indirect Costs $72,000Total $678,000

SCHATZENERGYRESEARCHCENTER

Interpretive Signs

The station has interpretive signage to inform visitors about what we’re doing, why we’re doing it, and how the station works.

SCHATZENERGYRESEARCHCENTER Compressor

• PDC single stage diaphragm compressor

• 6000 psig maximum discharge pressure

SCHATZENERGYRESEARCHCENTER

• Two 6000 psig ASME hydrogen storage tanks with a total capacity of 12 kg

• 30 gallon ballast tank between electrolyzer and compressor

Storage Tanks

SCHATZENERGYRESEARCHCENTER Dispenser

• FTI single hose dispenser• 5000 psig fill pressure• California Fuel Cell Partnership (CaFCP) fueling protocol and data support