Air Pollution Control Equipment Services, Emissions

A promising technology for a demanding future

Issue 6 and Volume 100.

ANN CHAMBERS

FUEL CELLS

A promising technologyfor a demanding future

Increasing power generation without increased emissions is one of the many challenges facing utilities today, and fuel cells may evolve into a key technology in facing that challenge. Fuel cells produce dramatically fewer emissions than plants running on conventional technologies, and their by-products, primarily water and CO2, are considered environmentally friendly.

There are three types of fuel cells that are receiving the most attention for power generation–phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC).

According to reports from the Department of Energy`s Morgantown Energy Technology Center, PAFCs are the most mature fuel-cell technology, already in the first stages of commercialization.

Turnkey 200-kW plants are available and have been installed in more than 70 sites in the United States, Europe and Japan. Operating at approximately 400 F, the PAFC plant also produces heat for domestic hot water and space heat and has an electrical efficiency exceeding 40 percent.

MCFCs are now being tested in a full-scale demonstration plant and offer higher fuel-to-electricity efficiencies, close to 60 percent. MCFCs operate at higher temperatures than the PAFCs, around 1,200 F, which makes them candidates for combined-cycle applications. When the waste heat is used, total thermal efficiencies with this type of cell can near 85 percent.

SOFCs are currently being demonstrated in a 100-kW plant and offer stability and reliability. High-temperature operation, up to 1,800 F, allows more flexibility in the choice of fuels and can pro