Utilities Use Diifferent Sources of Electric Power

Electric power companies use half a dozen different kinds of generating equipment to meet the demand for energy, in descending order:
• Coal-fired generators contribute about half of U.S. power;
• natural gas-fired plants one-fifth,
• nuclear another fifth;
• conventional hydroelectric sources just over 6 percent,
• other renewables (biomass, geothermal, solar, and wind) and other miscellaneous energy sources generated less than 5 percent of electric power (Figure 2).
• petroleum less than 1 percent.



















Figure 2: Net Generation Shares by Energy Source:
Total (All Sectors), Year-to-Date through April, 2010


Generators with lower fuel costs (such as coal or nuclear) are operated to supply so-called baseload power, and are kept on line 70% of the time or more. Lower factors show that generators are operated during peak demand periods and/or have high fuel costs, or their operation depends on the availability of the energy source, such as hydro and wind energy.