According to the U.S. Energy Information Administration, most electricity in the U.S. is produced by steam turbines. The turbines are powered by an assortment of fuels: fossil fuels such as coal, natural gas or petroleum; nuclear power; or renewables such as solar, wind or hydroelectric power. In the case of fossil fuels, they are burned in a furnace, which heats water in a boiler to produce steam, which then turns the turbine blades. The spinning turbine blades power a generator which produces electricity, which is then transmitted via poles and wires to your home and/or business.
According to 2012 EIA figures, fossil fuels generate the largest amount of electricity in the U.S. Of the 4 trillion kWh generated, coal accounted for 37 percent, natural gas 30 percent and petroleum less than 1 percent.
Another fairly large source is nuclear power, which accounts for approximately 19 percent. Electricity is produced using a nuclear reactor in a similar fashion as fossil fuel generators. Steam is still produced to power turbines, but the steam in a nuclear plant is produced via fission (i.e. the splitting of atoms). In this method, a reactor contains a core of nuclear fuel, which is usually uranium. Neutrons are injected into the core, splitting the uranium atoms to produce heat and more neutrons. These neutrons continue the chain reaction, creating more fission heat, and neutrons. The heat produced is used to make the steam used to power turbines, which then creates the electricity.
The cleanest sources of electricity are called renewables. Renewable energy sources vary. Hydropower is created by harnessing flowing water to spin turbines, and accounts for 7 percent of U.S. energy generation. Windpower is the next largest source, with approximately 3 percent of total U.S. output. Biomass, which is natural waste such as lumber mill leftovers, garbage or agricultural leftovers such as corn or wheat, can be burned to create the steam needed to power those ever-present turbines. Biomass accounts for only 1 percent of national output. Geothermal, which is heat energy produced from underground sources such as steam fissures, and solar, which harnesses the sun to produce electricity (most commonly through photovoltaic (PV) panels), each account for less than 1 percent but solar in particular is experiencing rapid growth across the U.S.
Most energy marketers get their electricity supply from a combination of energy sources so that they (and you) aren’t locked in to shifting prices in a single commoditySome states require energy suppliers to disclose the environmental content of the electricity that they supply. That way, you have the option of choosing a supplier with the fuel sources that you are most comfortable with. These environmental content labels provide not only the percentage of fuels used to generate the electricity purchased on your behalf, but also the levels of air pollutants associated with that generation compared to the average for your state. Many suppliers offer a “standard” electricity offer, or the same mix of sources typically found on your local grid, as well as one or more offers utilizing only renewable sources for all or some of the supply.
Depending on where you live, not only can you shop for an energy supplier, but you can also shop for the type of energy source you prefer.