Last May, the U.S. Department of Energy (DOE) slashed the federal budget request for hydrogen fuel-cell research in 2010 by $100 million to $68 million. Soon afterward, DOE Secretary Steven Chu made it clear that he does not expect fuel-cell vehicles to become commercially viable fast enough to merit priority funding at this time. He decided instead to favor in the new budget “nearer term” alternatives such as plug-in hybrids and biofuels.
The Nobel Prize-winning physicist told the MIT Technology Review, for instance, that lingering obstacles stand in the way of the gas’ use as an energy carrier in a future hydrogen economy.
“To get significant deployment, you need four significant technological breakthroughs,” Chu said. First, the chief sources for hydrogen—hydrocarbon fuels—release greenhouse gases when processed. In addition, onboard hydrogen storage continues to take up too much vehicle space, and the fuel cell units themselves remain too expensive to commercialize. Finally, the necessary infrastructure for distributing hydrogen has not been built.
“If you need four miracles, that’s unlikely,” Chu said. “Saints only need three miracles.”
Proponents of hydrogen research have since lobbied strongly to restore government support. Congress is considering likely votes to reinstate all of the funding for hydrogen and fuel-cell research. Hydrogen enthusiasts have further reason to smile: The stimulus bill passed earlier this year—the American Recovery and Reinvestment Act—provides $42 million for fuel-cell and hydrogen technology.
Recent funding moves aside, Chu’s priorities have led to changes in the DOE hydrogen effort. “With fuel cells now considered to be longer term technology, the hydrogen program has refocused on early market applications” such as material handling and stationary power-generation systems for supplemental, emergency, or uninterrupted power supplies, said Sunita Satyapal, Acting Program Manager at the DOE for Hydrogen, Fuel Cells & Infrastructure Technologies.
The stimulus money, she said, has been allocated to support immediate deployments of nearly 1000 fuel-cell systems for these applications, for which fuel-cell technology is competitive. Some of the fuel-cell units will power forklifts at several large corporations, including some at a FedEx facility in Harrison, AR, and some at an Anheuser-Busch plant in St. Louis, MO.
The fiscal roller coaster has, in the meantime, tended to overshadow what Satyapal called strong progress in hydrogen fuel-cell technology during the last few years. According to two independent cost analyses conducted by TIAX and Directed Technologies Inc., for example, state-of-the-art fuel-cell technology from 2008 could produce power at the rate of $73/kW if 500,000 units were manufactured a year. The estimated figure for 2002 fuel-cell systems is about $275/kW, and the DOE cost goal for 2015 is $30/kW.
The models, she said, considered an 80-kW fuel cell fitted with a lower cost prototype catalyst cathode integrated into the electrode assembly of a proton-exchange membrane. The durable, low-cost, high-performance cathode, which was developed by Mark K. Debe at 3M (with DOE support), cuts precious platinum use by replacing some of it with less expensive alloy of platinum, cobalt, and manganese. This substitution is enabled by 3M’s nanostructured thin-film support technology, which markedly enhances catalytic activity. The new cathode recently demonstrated more than 7300 h of durability in laboratory tests. About 5000 h of road operation would be needed to reach the DOE lifetime goal of 150,000 mi (240,000 km).
Storing enough hydrogen fuel to achieve a minimum 300-mi (480-km) driving range in a compact, lightweight package poses a challenge for current technology. Compared to hydrocarbon fuels, hydrogen gas features good energy density by weight but inadequate energy density by volume. For that reason, H2 storage tanks tend to be larger and heavier. High pressures—5000 to 10,000 psi (345 to 690 bar)—and cryogenic temperatures— -253°C (-423°F)—improve volumetric energy density but require extra energy and hardware to implement.
Researchers expect that next-generation storage technologies will exploit the ability of certain substances such as metal hydrides, metal organic framework molecules, and carbon nanotubes to reversibly release H2 upon heating. The technical difficulties of packing sufficient hydrogen in an average car have, however, abated somewhat of late, Satyapal said, because engineers have succeeded in shrinking the size and weight of fuel-cell stacks and ancillary support systems, which leaves more room for storage.
“More space is available in today’s fuel-cell vehicles, so current high-pressure storage containers will do the job for now,” she explained. The DOE is therefore relaxing its 2015 target goal for hydrogen storage efficiency of the next-generation technologies in the lab—one of many established under the National Hydrogen Storage Project. This capacity metric, expressed as the ratio of the weight of the stored hydrogen to the total weight of the storage medium, is being reduced from 9 to 5.5%.