Hydrogen Fuel Cells

by Betsy Hooper RA, CSI, CDT

In our modern world of information technology and in the world of medical care there is the need for a smooth, uninteruptable supply of electriccity. There are spikes in line voltage off the power grid that can kill sensitive high tech equipment. A failure of power in a hospital can be a matter of life or death. There are also locations so remote or otherwise inaccessible that it is not cost effective to get electricity from the power grid. In most of those cases generators burning any one of a number of hydrocarbon fuels are used. Burning of hydrocarbons to generate electricity is a source of pollution. It is also not a very efficient way to generate electricity. Enter the fuel cell.

Hydrogen fuel cells are substantially more efficient in generating electrical power than most combustion processes. They generate electricity directly from a chemical reaction in a process that was discovered over 150 years ago. Recent growth of support technologies make the process more efficient and cheaper. Interest in fuel cells is also driven by the need for cleaner and more efficient electricity generation processes. While the nature of the chemical reaction is completely different, a fuel cell is most easily likened to a battery. In a fuel cell, a catalyst breaks down the hydrogen molecule into a hydrogen ion and an electron. The ion passes through a membrane to react with oxygen at the cathode creating water, while the released electron goes to the anode and becomes the current we tap for power. Rather than being re-charged with electricity, the fuel cell is “recharged” by adding hydrogen. The chemicals involved in fuel cells are far less hazardous than those used in batteries, and the only byproduct of the chemical reaction is water and a little heat.

When a fuel such as oil or coal is used to generate electricity, there is a lot of waste in the form of both atmospheric pollutants and heat. The average grid efficiency of power generation is 30%. Today’s fuel cells operate with a 40% efficiency, and generate none of the offensive NOx and SOx emissions. Anticipated developments in fuel cell technology could easily increase their efficiency to 50% or greater.

While there are number of sources of pure hydrogen gas available today, there is not an infrastructure to support a hydrogen fuel economy. As a result front end fuel processors called reformers are used in conjunction with fuel cells to extract the hydrogen from our more common hydrocarbon fuels such as natural gas, methane, and methanol.

While fuel cells are of interest in buildings requiring independent power sources, the greatest drive in their development is for use in electric automobiles. Because they can be refueled like an ordinary car, there is not the issue of time required for recharging. Also, because the reaction generates heat as well as electricity, no power is wasted to heat the car in cold weather. As fuel cell technology develops and becomes more widespread, continued improvements in efficiency are anticipated. Once the market is large enough there should also be motivation for fuel manufacturers to provide hydrogen fuel directly, thus eliminating the need for reformers on the fuel cells.

Most architectural applications of fuel cells today are either for consciously green buildings such as Four Times Square, or as an alternative to backup generators in hospitals and nursing homes. A fuel cell power plant was also installed in New York City’s Central Park precinct because of the prohibitive cost of bringing new power lines to the building. While this old technology is still in its commercial infancy, we can expect to see and hear more about it in the coming years.

Information sources:

Environmental Building News, Vol. 8, No. 4 April 1999

Fuel Cells 2000 website at www.fuelcells.org