Energy derived from oil
Oil is the largest source of energy in the United States, providing close to 40 percent of all of the nation's entire power needs. Though most oil is used for transportation or home heating purposes, a small percentage is still used as a fuel for electricity generating plants. While oil continues to decline in popularity as an electricity fuel, in places such as New York, oil still comprises about 8 percent of the state's electricity fuel mix.
Oil sits in deep underground reservoirs. Like other fossil fuels, this liquid is the end-product of millions of years of decomposition of organic materials. Since the ultimate amount of oil is finite -- and cannot be replenished once it is extracted and burned it cannot be considered a renewable resource. Once extracted, oil can be refined into a number of fuel products: gasoline, kerosene, liquefied petroleum gas (such as propane), distillates (diesel and jet fuels) and "residuals" that include industrial and electricity fuels.
Three technologies are used to convert oil into electricity:
- Conventional steam - Oil is burned to heat water to create steam to generate electricity.
- Combustion turbine - Oil is burned under pressure to produce hot exhaust gases which spin a turbine to generate electricity.
- Combined-cycle technology - Oil is first combusted in a combustion turbine, using the heated exhaust gases to generate electricity. After these exhaust gases are recovered, they heat water in a boiler, creating steam to drive a second turbine.