TURN A SWITCH; A LIGHT COMES ON.
Mass generation of electricity has been taking place in the United States since 1881. Electricity, the movement of elec- trons, is caused by moving a magnetic field across a wire coil. The mechanical force to cause this movement was originally pro- vided by flowing water (moving a turbine) or combustion (generally coal) to generate steam, which in turn provided the needed mechanical energy.
Over time, additional fuels were added to the generation mix to provide thermal energy, including natural gas, petroleum derivatives, biomass, geothermal, nu- clear, other sources of mechanical energy (wind) and more recently, direct genera- tion from the sun (solar). Some fuel choices reflected geography; proximity to rivers and fuel (e.g., coal reserves), however, another key driver has been fuel cost and availability.