Crude oil is a thick, flammable, yellow-to-black mixture of gaseous, liquid and solid hydrocarbons that occurs naturally beneath the earth's surface, can be separated into fractions including natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, and asphalt and is used as a raw material for a wide variety of derivative products.
Oil is the world's main source of energy but is being challenged by alternative sources of energy like solar, wind, biomass, biofuels, wave, hydroelectric and geothermal energy. Solar panel installations are currently growing at a 50% rate since the cost of solar is closing in on the traditional, fossil fuel based forms of home energy.
Oil was formed from the remains of animals and plants that lived millions of years ago in a marine environment. Over the years, layers of mud covered the remains. Heat and pressure from these layers helped the remains turn into what we call crude oil. The word "petroleum” means “rock oil” or “oil from the earth.” Oil is a finite resource and there is great concern that we are in peril of running out. The Peak Oil Theory says that crude oil reserves are now declining and a mandatory switch to renewable energy is required.
Crude is a smelly, yellow-to-black liquid and is usually found in underground areas called reservoirs. Scientists and engineers explore a chosen area by studying rock samples from the earth. Sensitive instruments, such as the gravimeter, the magnetometer, and the seismograph, may be used to find subsurface rock formations that can hold crude oil. Drilling is a complex and risky process. Some wells must be dug several miles deep before petroleum deposits are reached. Many are drilled offshore from platforms standing in the ocean bed. Usually petroleum from a new well will come to the surface under its own pressure. Later the crude oil must be pumped out or forced to the surface by injecting water, air, natural gas, steam, carbon dioxide, or another substance into the deposits.
Among the leading producers of crude oil are Saudi Arabia, Russia, United States, Iran and China.
More than one-fourth of the crude oil produced in the United States is produced offshore in the Gulf of Mexico. The top crude oil-producing states are: Texas, Alaska, California, Louisiana, and Oklahoma. The amount of crude oil produced domestically has been getting smaller each year. However, the use of products made from crude oil has been growing, making it necessary to bring more oil from other countries.
After crude oil is removed from the ground, it is sent to a refinery by pipeline, ship or barge. At the refinery, different parts of the crude oil are separated into useable petroleum products. Crude oil is measured in barrels (abbreviated “bbls”). One barrel of crude oil, when refined, produces about 20 gallons of finished motor gasoline, and seven gallons of diesel, as well as other petroleum products. Most of the petroleum products are used to produce energy.
Even though petroleum products make life easier - finding, producing, moving, and using them can cause problems for our environment like air and water pollution. Exploring and drilling for oil may disturb land and ocean habitats. New technologies have greatly reduced the number and size of areas disturbed by drilling. If oil is spilled into rivers or oceans it can harm wildlife. While oil spills from ships are the most well known problem with oil, more oil actually gets into water from natural oil seeps coming from the ocean floor. Or, from leaks that happen when we use petroleum products on land.
Gasoline is used in cars, diesel fuel is used in trucks, and heating oil is used to heat our homes. When petroleum products are burned as fuel, they give off carbon dioxide, a greenhouse gas that is linked with global warming. The use of petroleum products also gives off pollutants - carbon monoxide, nitrogen oxides, particulate matter, and unburned hydrocarbons - that help form air pollution.
Source: US Department of Energy - EIA