Mark A. Hoberecht

Glenn Research Center, Cleveland, Ohio

NASA’s PEM Fuel Cell Power Plant Development

Program for Space Applications

NASA/TM—2008-214991

January 2008
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Prepared for the

2006 Fuel Cell Seminar

Honolulu, Hawaii, November 13–17, 2007

Mark A. Hoberecht

Glenn Research Center, Cleveland, Ohio

NASA’s PEM Fuel Cell Power Plant Development

Program for Space Applications

NASA/TM—2008-214991

January 2008
Available from

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Level of Review: This material has been technically reviewed by technical management.
NASA/TM—2008-214991 1 

NASA’s PEM Fuel Cell Power Plant Development Program 

for Space Applications 

Mark A. Hoberecht 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Introduction 

Proton-exchange-membrane (PEM) fuel cells were the primary electrical power source on both the 

Gemini and Apollo missions, and more recently, alkaline fuel cells have powered the Shuttle Orbiter. 

During the first twenty years of Shuttle operation, PEM fuel cell technology underwent only minor 

development for space applications, while development for commercial terrestrial applications was 

initiated and has grown exponentially. However, NASA recognized the advantages that PEM technology 

promises over existing alkaline fuel cell technology for space applications, and beginning in 2001, 

embarked on a five-year PEM fuel cell power plant development program. These advantages include 

enhanced safety, increased robustness, improved modularity, higher power levels, longer life, lower 

weight, improved reliability and maintainability, higher peak-to-nominal power capability, the ability to 

operate on lower purity propulsion-grade reactants, reduced ground and mission operations support, and 

lower recurring costs. NASA’s five-year program has been conducted by a three-center NASA team of 

Glenn Research Center (GRC, lead), Johnson Space Center (JSC), and Kennedy Space Center (KSC). The 

program was initially aimed at developing PEM fuel cell hardware for a reusable launch vehicle (RLV) 

application, but more recently has shifted to applications supporting the NASA Exploration Program. 

In contrast to the early days of PEM fuel cell technology development when NASA pioneered fuel 

cell development during the Gemini and Apollo eras, NASA is now able to leverage technology advances 

from the commercial sector in developing PEM fuel cell technology for space applications. The major 

differences between commercial terrestrial technology and space technology are that space fuel cells must 

be able to operate with pure oxygen as the oxidant (as opposed to air) and water removal must take place 

in a multi-gravity environment (from zero-gravity to several times that of Earth’s gravity). These 

challenges have been the primary focus of NASA’s development effort. The first phase of the effort, to 

develop breadboard hardware in the 1 to 5 kW power range, was conducted by two competing vendors 

under NASA contract. The second phase of the effort, to develop Engineering Model hardware at the 

10 kW power level, was conducted by the winning vendor from the first phase of the effort. Both 

breadboard power plants and the single engineering model power plant were delivered to NASA for 

independent testing. 

Breadboard Development Effort 

Phase I of NASA’s five-year program was the development of breadboard power plants by two 

competing vendors, ElectroChem, Inc. and Teledyne Energy Systems, Inc. This effort, which occurred 

during the first two years of the program, was concentrated on building power plants of sufficient size to 

demonstrate the capabilities of the two vendor’s technologies. The goal was to deliver power plants at 

minimum cost in a short period of time, hence off-the-shelf hardware was utilized as much as possible. 

Table 1 shows a comparison of the design parameters for the two breadboard units. 
NASA/TM—2008-214991 2 

TABLE 1.—BREADBOARD POWER PLANT COMPARISON 

Vendor ElectroChem Teledyne 

Nominal power, kW 1.0 5.0 

Number of cells 45 82 

Cell active area, cm2 232 302 

Nominal current density, mA/cm2 110 270 

Peak power capability, peak: nominal 6:1 >6:1 

Reactant rcirculation approach Passive (ejectors) Active (pumps) 

 

 

Figure 1.—ElectroChem breadboard schematic. Figure 2.—ElectroChem fuel cell stack. 

Figure 3.—Teledyne breadboard schematic. Figure 4.—Teledyne fuel cell stack. 

Figures 1 to 4 show schematic representations of the breadboard power plant units as well as photos 

of the individual fuel cell stacks within each breadboard unit. 

After design and fabrication, the breadboard power plant unit from each vendor was delivered to 

NASA for independent testing. Following several months of extensive performance testing under several 

load profiles, Teledyne was selected to participate in the engineering model portion of the program. 
NASA/TM—2008-214991 3 

Engineering Model Development Effort 

Phase II of NASA’s five-year program was the development of a single engineering model power 

plant by Teledyne Energy Systems, Inc. The goal of this effort, which took place during the final three 

years of the program, was to further advance PEM fuel cell technology at the system level. The fidelity of 

the engineering model power plant was to more closely resemble space flight hardware than the off-theshelf commercial hardware utilized in the breadboard power plants. Table 2 summarizes the key 

engineering model system requirements. 

The engineering model power plant as delivered to NASA fully met all of the above program goals, 

except for a 25 percent excess in power plant weight. Schedule and cost constraints prevented further 

reductions in balance-of-plant weight surrounding the fuel cell stack, which was the major contributor to 

the excess. Just as with the breadboard units, at the conclusion of design and fabrication the engineering 

model unit underwent independent testing by NASA. However, the engineering model testing was more 

extensive than that of the breadboards. The test regime included routine tests such as polarization curves, 

a variety of performance tests under multiple load profiles, specialty tests such as rapid start-up and lossof-coolant tests, and environmental tests such as thermal vacuum and vibration tests. A photograph of the 

engineering model in NASA GRC’s fuel cell test facility is shown in figure 5. 

TABLE 2.—ENGINEERING MODEL POWER 

PLANT KEY REQUIREMENTS 

Requirement Goal 

Nominal power, kW 7 to 10 

Voltage regulation, V 30±10 percent 

Voltage response time, s <0.2 

Operating life, hr 10,000 

Operating temperature, °C 60 to 80 

Operating pressure, kPa <690 

Power plant weight, kg <140 

Power plant volume, m3 <0.2 

Figure 5.—Teledyne engineering model fuel cell power plant. 
NASA/TM—2008-214991 4 

Summary 

Recognizing the advantages that PEM fuel cell technology promises over existing alkaline fuel cell 

technology used on the Shuttle Orbiter, NASA is completing a five-year PEM fuel cell power plant 

development program for future space applications. This effort has been conducted by a three-center 

NASA team led by Glenn Research Center in Cleveland, Ohio. By leveraging significant advances in 

commercial PEM fuel cell technology, NASA has successfully adapted terrestrial technology for space 

applications by addressing the key mission requirements of using pure oxygen as an oxidant and 

operating in a multi-gravity environment. 

Competing vendors developed breadboard units in the 1 to 5 kW power range during the first phase of 

the program, and a single vendor developed a nominal 10 kW engineering model power pant during the 

second phase of the program. This engineering model unit underwent a series of performance and 

environmental tests conducted by NASA to assess its applicability for future space missions. Although 

not yet of flight hardware fidelity, the PEM fuel cell engineering model power plant was very similar in 

terms of form, fit, and function to the alkaline fuel cell power plant used on the Shuttle Orbiter. With 

continued advances in fuel cell stack and balance-of-plant ancillary hardware, PEM fuel cell technology 

will be ready to meet the electrical power needs of future space missions. 
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NASA's PEM Fuel Cell Power Plant Development Program for Space Applications 

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Hoberecht, Mark, A. 

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John H. Glenn Research Center at Lewis Field 

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14. ABSTRACT

A three-center NASA team led by the Glenn Research Center in Cleveland, Ohio is completing a five-year PEM fuel cell power plant 

development program for future space applications. The focus of the program has been to adapt commercial PEM fuel cell technology for 

space applications by addressing the key mission requirements of using pure oxygen as an oxidant and operating in a multi-gravity 

environment. Competing vendors developed breadboard units in the 1 to 5 kW power range during the first phase of the program, and a 

single vendor developed a nominal 10-kW engineering model power pant during the second phase of the program. Successful performance 

and environmental tests conducted by NASA established confidence that PEM fuel cell technology will be ready to meet the electrical 

power needs of future space missions. 

15. SUBJECT TERMS

Fuel cells; Fuel cell power plants; Manned space flight; Reusable launch vehicles 

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