Fuel Cells for Transportation
The transportation sector is the single largest consumer of petroleum in the United States, accounting for nearly two-thirds of our annual consumption. Most of this, about 75 percent, is used to fuel highway vehicles, such as cars, trucks, and buses. In addition, highway vehicles are responsible for over 60 percent of the carbon monoxide emissions and about 20 percent of greenhouse gas emissions. A transportation system powered by hydrogen and fuel cells would significantly improve our national energy security and reduce emissions of harmful pollutants and greenhouse gases.
The Hydrogen, Fuel Cells & Infrastructure Technologies Program is working closely with the Vehicle Technologies Program to develop technologies that can advance state-of-the-art of fuel cell systems for highway vehicles. DOE is concentrated on supporting research into core technologies to improve fuel cell systems and their subsystems and components. DOE's fuel cell systems research is focused on compressor/expander technologies, thermal and water management technologies, physical and chemical sensors, and systems analysis.
Compressor/expandor technologies. Most current automotive fuel cell systems are designed for pressurized operation in order to reduce system size, boost stack efficiency, and improve water management. The program is working with research partners to improve turbo-compressor and blower designs, develop hybrid compressor/expander modules, and reduce subsystem costs.
Thermal and water management technologies. The low operating temperature of PEM fuel cells limits the use of heat generated by the fuel cell. More efficient heat recovery systems and improved system designs are needed to use fuel cell waste heat and water to minimize the overall system size without compromising overall system efficiency.
Physical and chemical sensors. Sensors are being developed to detect hydrogen leaks and monitor hydrogen purity, which is important for preventing degradation of the fuel cell catalyst.
Systems analysis. Analysis is used to provide a sound understanding of fuel cell systems and markets for both transportation and stationary applications.
In addition to fuel cell system research, DOE is sponsoring research to improve fuel cell subsystems and components and funding transportation "learning demonstrations" to prove fuel cell technologies in real-world applications.
Dual Pathway Development
DOE is pursuing PEM fuel cell systems fueled directly by hydrogen for fuel cell vehicles (FCVs). Prior to August 2004, significant fuel cell activity resources supported on-board vehicle fuel processing, where hydrogen could be produced from fuels such as gasoline, methanol, ethanol, natural gas or other hydrocarbons, supplied by the existing infrastructure. A review of on-board fuel processing activities was conducted. It concluded that, based on the current state of the technology, it was unlikely that on-board fuel processing would improve sufficiently to support the transition to a hydrogen economy. Subsequently, DOE decided to discontinue on-board fuel processing R&D and focus on direct hydrogen fuel cell systems for transportation.
Auxiliary Power Units
The Program is also sponsoring the development of auxiliary power units (APUs) that run on reformate fuels for use on commercial trucks. Since these APUs would most likely run on diesel, research is focused on diesel fuel processors that can produce hydrogen with minimal amounts of sulfur in the reformate.
The status of DOE's transportation fuel cell R&D projects—fuel processing, transportation systems and balance of plant components, and fuel cell characterization—is detailed in the fuel cells section of the Annual Progress Report.