Fuel cell sufficiency

Tuesday, March 04, 2008

JoAnn Milliken, Hydrogen Program Manager at the U.S. Department of Energy, and Senior Analyst at Sentech, Inc. Joseph Stanford discuss technological advances and future applications of fuel cell technology.

The energy challenges facing the United States are particularly apparent in the area of transportation. This sector is the source of several key factors influencing policy and spurring public debate, including the rising price of gasoline, our dependence on imported oil, and the fact that transportation accounts for nearly a third of our CO2 emissions. These concerns are most keenly felt in the area of light-duty vehicles – in 2005, they were responsible for 40% of our petroleum consumption, more than $70bn of imported oil, and an energy usage of 17 quadrillion BTUs (quads), of which only 3.4 quads was 'useful' energy (this amounts to an efficiency of less than 20%; by comparison, the freight transportation sector achieved roughly 40% efficiency).

Light-duty vehicles, therefore, have been the primary focus of the U.S. Department of Energy's (DOE) research and development efforts in transportation. Our current efforts include hydrogen and fuel cells, biofuels, hybrid vehicle systems, and energy storage technologies (primarily batteries). And our approach is to pursue these efforts concurrently, without bias for any particular technology. Ideally, the interplay of technologies in the marketplace will determine the optimal mix of vehicular power sources in the future.

We have focused considerable effort on fuel cell research because the potential benefits of fuel cell vehicles are substantial. A fundamental advantage of fuel cells is their efficiency, which has been verified in DOE's demonstration fleet at up to 58% – more than twice the efficiency of a typical gasoline engine. The optimum fuel for fuel cells is hydrogen, which can be produced from a number of low emission, domestic energy sources, including natural gas, biomass, coal (with carbon sequestration), renewable power and nuclear power. Fuel cells could eliminate oil use, criteria pollutants and CO2 emissions in the entire light-duty vehicle fleet.

Because fuel cell technology is scalable, it has applications across a wide range of industries. Many of these applications offer similar benefits to those of fuel cell vehicles (reduced emissions, fuel flexibility, and increased efficiency). Hence, we are also developing fuel cells for stationary and portable applications, and for niche markets such as forklifts. Several of these applications will achieve commercialisation before fuel cell vehicles, and several already have. In addition, we are supporting the growth of these early markets to expand the domestic supplier base, increase manufacturing volumes, and diminish other barriers that will also confront fuel cell vehicles – such as the lack of awareness of the technology and uncertainty among potential investors and end-users.

To move hydrogen and fuel cells forward, the President's Hydrogen Fuel Initiative was launched in 2004 to accelerate DOE activities addressing the major technical and institutional challenges facing the commercialisation of these promising technologies. This expanded programme leverages a broad base of expertise – at its core is a research and development (R&D) effort that involves the work of universities, national laboratories, and industry. The programme works closely with the auto and energy companies through the FreedomCAR and Fuel Partnership, to help guide critical pre-competitive R&D efforts and to facilitate the transfer of technology to industry.

Our R&D efforts are guided by the goal of advancing hydrogen and fuel cells to be competitive with current technologies. For light-duty vehicles, this means developing an 80 kilowatt polymer electrolyte membrane (PEM) fuel cell by 2015 that can be manufactured at high volume for $30 per kilowatt with an operating lifespan of 5,000 hours (equal to roughly 150,000 miles of driving). These targets must be met along with a number of other requirements, such as 60% peak efficiency, tolerance to fuel impurities, size and weight limitations, and so on. The programme also aims to develop technologies for compact, low pressure storage of hydrogen onboard vehicles, and to enable the development of a refuelling infrastructure by reducing the cost of producing and delivering hydrogen. To validate the progress of these efforts and provide valuable feedback to our R&D efforts, the programme has partnered with industry to operate 77 fuel cell vehicles and 14 refuelling stations.

While light-duty vehicles are our primary focus in the transportation sector, we are now analysing data from the U.S. Department of Transportation's fuel cell bus demonstrations, which currently include 12 buses operating in five States. We are also developing fuel cells for auxiliary power units (APUs) for heavy-duty vehicles and recreational vehicles, in the 3-30kW range. Other organisations are exploring fuel cells as primary power for highway freight vehicles and trains and APUs for ships and aircraft.

Progress to date in fuel cell R&D has been substantial. The programme has reduced the projected high volume manufacturing cost of automotive fuel cells nearly three-fold in four years (from $275/kW in 2002 to $110/kW in 2006). Durability of fuel cell stacks has improved to 2,000 hours, and two of our projects have developed fuel cell membranes with durability close to our target of 5,000 hours.

To overcome the remaining barriers, the programme has focused on four main areas: 'catalysts and supports', which are crucial to reducing cost; 'water transport', which enables improvements in the flow of water through a fuel cell; 'membranes', which play an important role in durability; and 'characterisation and analysis', which involve computer modelling and laboratory testing. In addition to these areas, the programme continues to pursue fundamental scientific breakthroughs and innovative concepts, which include new designs and novel materials.

As we have moved further along the path of technology development, it has become clear that the fuel cell is no longer just a promising but unproven technology. It is a technology with demonstrated commercial applications (in portable devices, forklifts, and back-up power). Fuel cells are well on their way to fulfilling the even greater promise of replacing the internal combustion engine with a cleaner, more efficient technology for the transportation sector.

Co. Author Joseph Stanford, Senior Analyst at Sentech, Inc.