A fuel cell is a device that generates electricity by a chemical reaction that takes place at the two electrodes (anode and cathode). Fuel cells also have an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes. Hydrogen is the basic fuel, but fuel cells also require oxygen. One great appeal of fuel cells is that they generate electricity with very little pollution–much of the hydrogen and oxygen used in generating electricity ultimately combine to form a harmless byproduct, namely water.
Fuel cells are scalable and range in size from units that power consumer electronics, to passenger cars and buses, and even large-scale plants that power neighborhoods, businesses, and more. Fuel cells are a family of technologies, producing zero or near-zero air pollutant emissions when generating electricity, which can operate on a range of hydrogen-rich fuels. When pure hydrogen is used in a fuel cell, the only by-products are electricity, heat and water. Fuel cells do not need to be periodically recharged like batteries, but instead continue to produce electricity as long as a fuel source is provided.
There are several fuel cell types, each with its own unique chemistry. These different types of fuel cells are characterized by their electrolyte, providing different attributes and benefits such as varying fuel types, operating temperatures, energy efficiencies, and applications of use.
High temperature fuel cells, such as molten carbonate fuel cells (MCFCs) or solid oxide fuel cells (SOFCs), are capable of internal fuel reforming to directly generate power from fossil fuels without intermediate steps. The high operating temperature allows these types of fuel cells to be unaffected by chemical compounds such as carbon monoxide or carbon dioxide that can adversely affect other systems. These high temperature fuel cells can utilize various fuels, including natural gas, biogas, and syngas.
MCFCs and SOFCs are primarily used for stationary power generation applications for homes and businesses, and large-scale generation by electric utilities. These systems range in scale from a few hundred kilowatts (enough to power a home or small business ) up to tens of megawatts, generating enough electricity to power tens of thousands of homes. Today, hundreds of systems are providing both primary power and back-up power across the country in a range of applications, including data centers, utilities, retail facilities, universities, hospitals, and more.
Syngas can also be reformed to produce a high-hydrogen stream that can then be further purified for use in lower temperature fuel cells that require a high-purity hydrogen stream. As more markets develop for low temperature fuel cells, and existing ones continue to grow, this will increase the demand for hydrogen fuel and pathways such as reforming syngas to generate it.
For additional information on fuel cells, please see the Fuel Cell and Hydrogen Energy Association website at www.fchea.org. The GSTC would like to thank the Fuel Cells and Hydrogen Energy Association for their assistance with this section.