Hydrocarbon resources are resources that contain hydrocarbon molecules which means it consists both hydrogen and carbon. Hydrocarbon resources are often known as fossil fuels (natural gas, oil, and coal) since hydrocarbons are the primary constituent in these. Hydrocarbon resources are the largest source of primary energy, contributing to over 85% of the world's primary energy.
A resource refers to any particular thing that is valued by humans because it has the ability to meet a certain need or desire. However, the Energy sector is concerned with a specific type known as a natural resource. Natural resources like hydrocarbons are useful since they can be used as fuel to provide services such home heating, electricity and transportation. The occurrence is used to describe all the natural resources that exist on earth—undiscovered and discovered.
Fossil fuel resources are simply hydrocarbon resources, given a different name. Fossil fuels are a category of fuels that are made by slow geological processes acting on dead organisms that are hundreds of millions of years old. Therefore, due to the time it takes for them to form, fossil fuels are not considered a renewable energy source. The most common types hydrocarbon resources include:
Oil is extracted as crude oil and is distilled using fractional distillation to extract different types of fuels from the oil. Crude oil is the main liquid component of petroleum formed after kerogen is heated and compressed over large periods of time. Crude oil itself is a complex mixture of hydrocarbons, so the exact composition of petroleum is never the same. Generally crude oil is about 85% carbon by weight, with the rest composed of mostly hydrogen. However, significant quantities of sulfur, oxygen, and nitrogen can also be present.
Natural gas is a colorless, odorless gas that burns readily and is a fairly extensive fuel used around the world. Chemically, natural gas is mostly methane—one specific hydrocarbon molecule. Natural gas has gained popularity as a fuel over the years, especially in the US where most of the natural gas used doesn't have to be imported from other countries. Natural gas can also be used as an alternative fuel for vehicles when it is compressed in the form of compressed natural gas.
Coal is a rock formed from the decomposition of plant life. It is composed mainly of carbon, with many other trace elements. Coal's high energy density makes it useful as a fuel for electricity generation in coal-fired power plants, and in some places, heating. Coal can be extracted in a number of different "grades". The lowest quality of true coal is lignite coal, then sub-bituminous, bituminous, and finally high quality anthracite coal. Coal is formed from peat which is technically a fossil resource, however it is not used extensively.
Unconventional resources are generally oil or natural gas resources that do not appear in traditional formations and must use specialized extraction or production techniques to obtain. For oil and gas, conventional deposits are porous and permeable rocks below ground that have tiny connected pore spaces which contain oil or natural gas. Unconventional resources are locked in geological structures where extraction is not economically or technologically feasible without the relatively recent technological advancements that can turn these into viable hydrocarbon reserves. Advances in technologies including hydraulic fracturing is making the extraction of these resources more viable.
When hydrocarbons are used, they undergo a process known as combustion. This means that hydrocarbons react the with oxygen in the atmosphere to form carbon dioxide, water vapour and heat. The environmental impacts of burning these hydrocarbons are drastic because combustion releases a significant greenhouse gases. In addition to these greenhouse gases (which is the leading cause of climate change), the burning of oil, coal, and natural gas releases pollutants like NOx, SOx, particulate matter, volatile organic compounds, carbon monoxide, and mercury.
The extraction of some of these resources can also result in environmental changes. Coal mining, particularly strip mining, can result in the destruction of wildlife habitats and forests to make room for mining sites. This removal of fauna can result in erosion and pollution of waterways with sediment. Moreover, hydraulic fracturing necessary to obtain some unconventional natural gas is questionable because of contamination as a result of the use of fracturing fluid.
Currently, the quantity of hydrocarbon resources that exist in the ground are declining (particularly light petroleum) but demand is growing. This is confusing because hydrocarbon reserves are increasing due to the improvements of technology and lower price, allowing us to attain previously 'unattainable' resources (see Reserve vs occurrence). Despite the increasing reserve (and decreasing occurrence), the demand and continued extraction lead a geophysicist named Hubbert to predict that the production of oil would peak in the 1970s and decline after this. This prediction regarding the decreasing production of oil is known as Hubbert's peak.
As consumption of resources increases, alternate energy is being explored to meet emerging energy and environmental demands. Some of these potential alternatives include nuclear, solar, geothermal, and wind.