Electrical Uses 2016

Natural gas, because of its clean burning nature, has become a very popular fuel for the generation of electricity. In the 1970s and 1980s, the choices for most electric utility generators were large coal or nuclear powered plants.  However, due to economic, environmental and technological changes, natural gas has become the fuel of choice for new power plants built since the 1990s. In fact, the Energy Information Administration (EIA) estimates that between 2009-2015, 96.65 gigawatts (GW) of new electricity capacity will be added in the U.S. Of this, over 20 percent, or 21.2 GW, will be natural gas additions. The graph below shows how, according to the EIA, natural gas-fired electricity generation is expected to account for 80 percent of all added electricity generation capacity by 2035.

There are many reasons for this increased reliance on natural gas to generate our electricity. While coal is the cheapest fossil fuel for generating electricity, it is also the dirtiest, releasing the highest levels of pollutants into the air. The electric generation industry, in fact, has traditionally been one of the most polluting industries in the United States. Regulations surrounding the emissions of power plants have forced these electric generators to come up with new methods of generating power, while lessening environmental damage. New technology has allowed natural gas to play an increasingly important role in the clean generation of electricity. Click on the link for more information on the environmental benefits of natural gas, including its role as a clean energy source for the generation of electricity.

Steam Generation Units

Natural gas can be used to generate electricity in a variety of ways. The most basic natural gas-fired electric generation consists of a steam generation unit, where fossil fuels are burned in a boiler to heat water and produce steam that then turns a turbine to generate electricity. Natural gas may be used for this process, although these basic steam units are more typical of large coal or nuclear generation facilities. These basic steam generation units have fairly low energy efficiency. Typically, only 33 to 35 percent of the thermal energy used to generate the steam is converted into electrical energy in these types of units.

Centralized Gas Turbines

Gas turbines and combustion engines are also used to generate electricity. In these types of units, instead of heating steam to turn a turbine, hot gases from burning fossil fuels (particularly natural gas) are used to turn the turbine and generate electricity. Gas turbine and combustion engine plants are traditionally used primarily for peak-load demands, as it is possible to quickly and easily turn them on. These plants have increased in popularity due to advances in technology and the availability of natural gas. However, they are still traditionally slightly less efficient than large steam-driven power plants.

Combined Cycle Units

Many of the new natural gas fired power plants are known as ‘combined-cycle’ units. In these types of generating facilities, there is both a gas turbine and a steam unit, all in one. The gas turbine operates in much the same way as a normal gas turbine, using the hot gases released from burning natural gas to turn a turbine and generate electricity. In combined-cycle plants, the waste heat from the gas-turbine process is directed toward generating steam, which is then used to generate electricity much like a steam unit. Because of this efficient use of the heat energy released from the natural gas, combined-cycle plants are much more efficient than steam units or gas turbines alone. In fact, combined-cycle plants can achieve thermal efficiencies of up to 50 to 60 percent.