A fuel cell generator is a device that generates electricity through electrochemical reactions instead of the combustion of fuel. Though they are often associated with pure hydrogen technologies, fuel cell generators can use a variety of fuel sources, including traditional fossil fuels such as natural gas. A fuel cell generator uses multiple fuel cells grouped into a “stack” along with supporting components to produce electricity of the desired voltage and current. Generators utilizing fuel cell technology have been produced in a variety of sizes, ranging from small portable units to tractor-trailer size generators capable of powering small towns.
At the heart of any fuel cell generator are fuel cells, which use electrochemical reactions rather than the burning of fuel to produce electricity. This makes fuel cell technology much cleaner than conventional generators, which produce byproducts such as ash, carbon dioxide, and smog-forming pollutants as they ignite and burn fuel. There are many types of fuel cells and a wide variety of materials may be used in their construction, but the basic principle remains the same: a fuel source triggers multiple chemical reactions with components of the fuel cell to produce electrons. Though they are often considered synonymous with hydrogen power, fuel cells can use traditional fossil fuels such as natural gas. An alternative fuel, such as biogas or methane, can also be used in many designs.
A single fuel cell on its own cannot create enough electricity to be useful in most applications, so they are often grouped into what is known as a fuel cell stack. The number of individual cells in a stack depends on the intended use of the system, and a large fuel cell generator may include multiple stacks. In addition to the stack or stacks, the generator contains other components such as insulation, storage tanks for fuel, and devices used to extract hydrogen from different fuel sources. If the generator is used to supplement or replace the electric grid, an inverter must be used to convert the direct current (DC) produced by the fuel cells into alternating current (AC) used in the grid and home appliances.
Since the number of fuel cells in a stack can vary, a fuel cell generator can come in a wide range of sizes. Some very small products are targeted at charging consumer electronics devices, such as mobile phones and notebook computers. Residential fuel cell generators, usually producing between 1 and 5 kilowatts, are often used in something called a combined heat and power (CHP) system to provide a home with both electricity and heat. Larger, tractor-trailer size units can be used by utility companies to feed extra power into the electrical grid during periods of high demand. Mobile units have been produced to power cars, buses, submarines, and even spacecraft.