FUEL CELL
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What Is It and How Does It Work?

Fuel cells are devices that produce electricity through an electrochemical reaction between hydrogen and oxygen. There is no combustion involved, and the only by-products of the fuel cell process are water and heat, so fuel cells do not produce any pollution. Fuel cells operate quietly and at very high efficiencies, especially when the heat produced is used  in other building applications, such as hot water heating or space heating.

Fuel cell technology has only fairly recently begun to be considered in widespread building applications. It was first developed in the nineteenth century, and the first large-scale use began in the 1960s by NASA for space vehicles. However, the fuel cell is a promising technology that will likely continue to develop into a useful tool to reduce energy costs in buildings. 

Fuel cells have three primary components: an anode side, a cathode side, and a membrane in between. When hydrogen gas enters the anode side, a platinum catalyst separates the proton and the electron in the hydrogen atoms. The proton passes through the membrane to the cathode side, while the electron travels through an electrical circuit. By passing through the electrical circuit, the electron produces electricity. Once it arrives in the cathode side of the fuel cell, the electron rejoins the proton, along with oxygen, to create water and heat.


Why Should I Consider It?

Fuel cells are a potentially beneficial and life-cycle cost-saving option in larger buildings that need a continuous source of electricity. Although upfront costs are generally higher than other energy generation systems, they also have some advantages. Fuel cells produce a continuous source of power and do not require backup generators, they operate at high efficiencies, and they produce very little noise. Many types of fuel cells can run on a wide range of hydrocarbon fuel sources, such as natural gas, methanol, ethanol, propane, diesel, and gasoline. In some studies, fuel cells have reduced energy costs by 20 to 40 percent as compared with traditional sources of electricity.


What Are the Options?

There are several different types of hydrogen fuel cells in various stages of reliability and economic feasibility.

Phosphoric acid fuel cells (PAFC) are currently the most widely available fuel cells. They are most suited for large-scale buildings due to their size and the amount of energy they produce. PAFC units can operate with hydrogen that has relatively high levels of impurities, which is a big advantage. They are, however, expensive, large, and heavy, so are generally not applicable to single-family home installation.

Proton exchange membrane fuel cells (PEM) are a promising technology for small-scale applications, such as single-family homes. This type of fuel cell unit operates at relatively low temperatures and has a high power density, meaning it produces a high amount of energy for a small size. A 3 to 5 kW PEM unit that is about the size of a refrigerator can provide power for a typical home. However, as PEM technology continues to develop, current units are very sensitive to impurities in the hydrogen fuel. As a result, maintenance and repair costs can be quite high.

What Are the Potential Benefits?

Hydrogen fuel cells operate at efficiencies of 40 to 60 percent. By comparison, a gasoline internal combustion engine is less than 20 percent efficient. Fuel cells therefore use less than half of the fuel than a conventional engine, even before considering the greatly increased efficiency achieved by reusing heat produced by the fuel cells in a cogeneration plant.

Are There Health and Safety Concerns?

Hydrogen fuel, like any fuel, must be handled carefully and contained properly. However, if properly handled, there is little health or safety risk.

How Much Does It Cost?

Current fuel cells range from $3,000 to $4,000 per kilowatt. There are many companies that are continuing to develop fuel cell technology with the aim of bringing prices down to $1,000 to $2,500 per kW. Operating costs and differential savings over time depend on several factors, including the cost of traditional sources of electricity and the cost and availability of a hydrogen-based fuel source.

What Else Should I Know?

Several companies are continuing to develop fuel cell technology in order to make this type of energy more cost-effective for single-family home applications. Although they may be cost-prohibitive now, fuel cell prices will most likely decline in the coming years. Many residential fuel cell units run on hydrogen-based fuels that are easy to find in most locations, such as propane and natural gas. 

Where Can I Get More Information?

U.S. Department of Energy: Energy Efficiency & Renewable Energy
U.S. Department of Energy
Whole Building Design Guide
U.S. Department of Energy Hydrogen Program