Fuel Cells and Their Landfill Applications

By Thomas Regan, Dana Megowan, and Li Zhang

a. Penrose landfill combines oxygen with hydrogen extracted from LFG, much like a battery fueled by LFG. It is approximateley 85% efficient where coal is only about 35% efficient. The gas from the Penrose landfill is mainly a mixture of methane with a small portion of sulpher (and a few other chemicals to boot), and is running at about 30% efficiency with a PC25 feul cell.

b. A coal-gasification plant in Wilsonville, Alabama uses gas generated from coal to create electricity in a fuel cell. This fuel cell required very pure fuel and suffered from fuel purity problems. Coal is very abundant in the US and this new fuel cell offeres an opportunity to create an environmentally friendly fuel source. “According to the Department of Energy's Office of Fossil Energy, the U.S. has 350 years worth of coal reserves.” The SOFC fuel cell has an opperating temperature of 750 degrees C. The fuel that the fuel cell used consisted of a mixture of carbon monoxide, hydrogen, carbondioxide, methane, water, and nitrogen. The experimental units can generate between 1 and 25 kilo-Watts of power.

100. One of the ways that fuel cells deal with the problem of carbon is to capture the carbon in a carbon filter that can be removed and cleaned/replaced periodically. This carbon may have applicable uses in other fields such as gasification used to fuel other carbon friendly fuel cells, like the one in Willsonville, Alabama. “ It was demonstrated that two gaseous streams containing CO/CO2-free hydrogen-rich gas ([H2]=90 v.%, balance methane) and synthesis gas (nH2 + mCO) could be produced from gaseous and liquid hydrocarbons via cyclic pyrolysis/gasification process using durable sulfur-resistant Fe-catalyst. The fuel conditioning unit and the solid oxide fuel cell operate at close temperature range (800-900oC) potentially making the integration and thermal management of the entire system relatively easy. (http://oasys2.confex.com/acs/225nm/techprogram/P615108.HTM)

d. Information on Coffin Butte Landfill

Current power generation – 2.5 MW

Potential power generation – 5 MW

Annual power generation – 21,000 Mw-hours

Capacity factor (CF) – 98%

Conversion technology – Internal combustion (IC) engines

Commercial operation – October 1995

Estimated Methane generation (mmscf/d) – 1.48

e. An average family uses 11,700 KW per year, and the general trend is upwards. We use electric energy for anything from heating buildings and providing light, to running aplliances and machinery. 11,700 KW can be generated by a;bout 5 metric tons of coal or by 150,000 cubic feet of natural gas.