Hydrocarbon

A hydrocarbon is an organic chemical compound composed exclusively of hydrogen and carbon atoms. Hydrocarbon molecules naturally occur and are found in crude oil, natural gas, coal and other important sources of energy. Burning hydrocarbons in the presence of sufficient oxygen produces carbon dioxide, water and heat, which is why hydrocarbons are desirable as fuels.

Methane, the main component of natural gas, is the simplest hydrocarbon because of the way it is structured. The four classes of hydrocarbons are aromatics, alkanes, alkenes (olefins) and alkynes (acetylenes). The way the hydrogen and carbon atoms are arranged and the types of chemical bonds that connect them determine what product they create. Crude oil, tar, bitumen and condensate are all petroleum hydrocarbons - that is liquids that contain hydrocarbons. Propane, butane and methane are gas hydrocarbons. Coal also contains hydrocarbons, but the geological process that produce solid coal press out most of the hydrogen and oxygen atoms, leaving a carbon rich solid. Although hydrocarbons are technically just some of molecules contained within oil, natural gas and coal, these three substances are often referred to as hydrocarbons in and of themselves.  

Hydrocarbons form naturally from plant and animal remains that are compressed through temperature and pressure over millennia, deep within the earth, in porous rocks like sandstone, limestone and shale. These types of rock exist in large bodies of water, especially oceans, and the natural gas and petroleum gradually rise through the rock and closer to the water’s surface (but still thousands of feet deep) and form a reservoir. Oil and natural gas exploration companies look for these geological formations to find potential reservoirs to extract.

Different techniques are used to extract hydrocarbons depending on their type and the material they’re contained in. For example, hydraulic fracturing is used to extract natural gas from shale by cracking the rock and using pressurized liquid to force the gas up through a well to the earth’s surface. Similarly, oil sands are unconventional deposits of crude that are mixed in with sand or partially formed sandstone, requiring the deposit to be mined. A conventional vertical or horizontal well is used when a productive formation is easily accessed.

Hydrocarbons are, of course, the main source of energy around the world. The uses of hydrocarbons go far beyond simply providing fuel that can be converted into energy. Through refining, petroleum has provided a wide range of derivative materials that play critical roles in the world economy, including plastics, solvents and lubricants. If all machinery were converted to renewable energy today, hydrocarbon extraction would still be required for these derivative products. This dependence on fossil fuels has led to the term hydrocarbon economy being used to describe the current global economy.

There is an environmental cost to burning hydrocarbons for energy. Greenhouse gasses released during combustion are contributing to climate change and the extraction process exacts a toll from natural habitats. Many argue that the externalities of the hydrocarbon economy are much higher than any cost savings from their uses as a fuel source. For this reason, alternative energy sources like solar, nuclear, wind and geothermal are being explored. Currently, however, the cost competitiveness of these alternative sources is not sufficient to wholly replace hydrocarbons.