What is the difference between coal and ethanol?

Answer 1

The term petroleum comes from the Latin stems petra, "rock," and oleum, "oil." It is used to describe a broad range of hydrocarbons that are found as gases, liquids, or solids beneath the surface of the earth. The two most common forms are natural gas and crude oil.

Natural gas is a mixture of lightweight alkanes. A typical sample of natural gas when it is collected at its source contains 80% methane (CH4), 7% ethane (C2H6), 6% propane (C3H8), 4% butane and isobutane (C4H10), and 3% pentanes (C5H12). The C3, C4, and C5 hydrocarbons are removed before the gas is sold. The commercial natural gas delivered to the customer is therefore primarily a mixture of methane and ethane. The propane and butanes removed from natural gas are usually liquefied under pressure and sold as liquefied petroleum gases (LPG).

Natural gas was known in England as early as 1659. But it didn't replace coal gas as an important source of energy in the United States until after World War II, when a network of gas pipelines was constructed. By 1980, annual consumption of natural gas had grown to more than 55,000 billion cubic feet, which represented almost 30% of total U.S. energy consumption.

The first oil well was drilled by Edwin Drake in 1859, in Titusville, PA. It produced up to 800 gallons per day, which far exceeded the demand for this material. By 1980, consumption of oil had reached 2.5 billion gallons per day. About 225 billion barrels of oil were produced by the petroleum industry between 1859 and 1970. Another 200 billion barrels were produced between 1970 and 1980. The total proven world reserves of crude oil in 1970 were estimated at 546 billion barrels, with perhaps another 800 to 900 billion barrels of oil that remained to be found. It took 500 million years for the petroleum beneath the earth's crust to accumulate. At the present rate of consumption, we might exhaust the world's supply of petroleum by the 200th anniversary of the first oil well.

Crude oil is a complex mixture that is between 50 and 95% hydrocarbon by weight. The first step in refining crude oil involves separating the oil into different hydrocarbon fractions by distillation. A typical set of petroleum fractions is given in the table below. Since there are a number of factors that influence the boiling point of a hydrocarbon, these petroleum fractions are complex mixtures. More than 500 different hydrocarbons have been identified in the gasoline fraction, for example.

Petroleum Fractions