Fuel cells are electrochemical devices that combine hydrocarbon fuel with oxygen from ambient air to produce electricity and heat.

TECHNOLOGY
Liquid hydrogen results from a chemical reaction between hydrogen fuel and an oxidizing catalyst. The hydrogen fuel used in the process is a by-product of petroleum refining. After hydrogen is liquefied at -253 oC, it is oxidized to void heat that escapes from the reaction. Fuel cells are electrochemical devices that use this process - combining hydrocarbon fuel with oxygen from ambient air - to produce electricity and heat. Compressed hydrogen is the gaseous state of hydrogen that is compressed in order to reduce the volume that uncompressed hydrogen takes for storage.1

TYPES
Fuel cells are emerging as a viable alternative energy technology primarily for power generation and transportation.

• Stationary fuel cells: Applications can produce a range of 300 kilowatts to 2.4 megawatts. These plants can act as base load power plants for supermarkets, large hotels, universities, or supporting the power grid at large. There are a number of technologies on the market, the most common being phosphoric acid fuel cells (PAFC), solid oxide (SOFC), molten carbonate (MCFC), and proton exchange membrane (PEM). The difference in the technologies being which electrolyte is used as a conductor.

• Fuel cell vehicles: Advances in fuel cell technology have been made for use in automobiles. Alkaline fuel cells (AFCs) are the standard focus of research and mainstream application in automobiles. Whereas AFCs are the prime movers of automobiles, SOFCs are being researched for use as an auxiliary power in automobiles. Solid oxide fuel cells can work in conjunction with typical gasoline fuel.2 For more information on fuel cell vehicles see the transportation section.

ENVIRONMENTAL IMPACT
Fuel cells have low emissions of pollutants such as nitrogen oxides and sulfur oxides as well as dramatically less emissions of carbon dioxide.

BENEFITS
Fuel cells are highly efficient and renewable energy sources. Fuel cell power plants can be47% efficient in the generation of electrical power and up to 80% efficient overall in combined heat and power applications. Typical fossil fuel-powered plants operate at about 35% electrical-power generation efficiency. Power generated from fuel cells is home grown and adds to the nations continued effort of energy independence.

DISADVANTAGES
The challenges of opening AFCs and SOFCs up to widespread implementation include: inventing methods for keeping carbon dioxide out of the fuel cell's air supply; the materials used in SOFCs are ceramic and prone to fracture; and, start-up times of SOFCs are long because of poor mechanical properties.

VALLEY ACCESS POTENTIAL
There are a number of fuel cell installers in California and a handful of stationary fuel cell installations can be found in the Valley. Californians can qualify for fuel cell rebates from the state as well as federal tax credits.

STATIONARY FUEL CELLS IN THE GREAT CENTRAL VALLEY
The Sierra Nevada Brewing Company (SNB) in Chico installed four 250-kilowatt co-generation fuel cells to supply electricity to their facilities. SNB also recovers heat lost during the fuel cell process for use in the brewery. For more information on the fuel cell installation at SNB, visit www.sierranevada.com/environment/fuelcells.html.

For more information on fuel cells visit the U.S. Dept. of Eneregy at
www1.eere.energy.gov/hydrogenandfuelcells

1 Hydrogen Economy: www.h2-economy.com/compressed-hydrogen.html (last accessed April 22, 2009)
2 US DOE EERE: www1.eere.energy.gov/hydrogenandfuelcells/glossary.html (last accessed April 22, 2009)