energy – coal, petroleum, natural gas and nuclear – should be familiar to practically everyone on our planet, which they affect with the pollution that results from their use. But what exactly do we know about these four prevalent non-renewable energy sources?
Coal is a black rock that can be burned to produce energy, it has the largest supply of the non-renewable fossil fuels¹. Coal is made from plant fossils. There are 5 main types of coal, in order of highest carbon content to least: Anthracite, Bituminous, Subbituminous and Lignite². It is dug up from the ground where it is in seams that are trapped between two layers of rock³.
Globally in 2013 we used 7,876 metric tonnes of coal, this was a 70% increase from 2000 ⁴.
Coal is harmful to the environment because when it is mined it destroys the local landscape, burning it releases toxins into the air and the process of generating power from it uses a lot of water⁵,³. Some of the merits of using coal are that it can be used as soon as it is dug up, it is cheap to mine and coal supplies are larger than oil and gas³.
Petroleum is the least abundant non-renewable energy source⁶. It is liquid fossil fuel made up from fossilised animals⁴. When extracting oil from the ground it comes out in the form of crude oil. This needs to be refined into different petroleum products. One US barrel of oil is 42 gallons of crude oil. When it is refined around 45 gallons of petroleum products are created through refinery processing gain. The products created are gasoline, ultra-low sulfur distillate, jet fuel, hydrocarbon gas liquids, heavy fuel oil and heating oil as well as some other products⁷. Petroleum is extracted by drilling into where it is trapped between 2 layers of rock, a pipe is then inserted in the hole to siphon it to the surface³.
The world used 35 billion barrels of oil in 2016 ⁸.
There are however many environmental impacts to using oil. When burned it releases toxins into the air which include greenhouse gases. There is also a risk of oil spills. For example, if there is a problem when drilling it can spill out of the well onto the sea and land causing environmental disasters¹. The advantages of oil are that it is the fuel that has made modern transportation possible, it is relatively cheap to produce and use¹⁰,⁴. It is also used to create many synthetic materials, plastic, chemicals and asphalt¹¹.
Natural gas is the second most abundant non-renewable energy source⁷. Natural gas is predominantly methane¹. It was formed like the other fossil fuels with pressure and heat on organic material over millions of years. When natural gas is initially extracted from the ground we get wet natural gas because it usually contains liquid hydrocarbons and non-hydrocarbon gases. To separate methane and other useful gases from wet natural gas it has to be processed¹².
Natural gas is found a few hundred metres underground between 2 layers of rock. A hole is drilled into the ground and pipes are inserted into that hole to funnel it to the surface to be processed and stored. It is most often used in houses for heat and cooking¹,⁴.
The total amount of natural gas consumed in the world in 2010 was 113 trillion cubic feet¹³.
Its extraction causes environmental problems: fracturing rocks can create small earthquakes, high-pressure water and chemicals which are forced underground during the extraction process can leak into water sources. When burned it gives off toxins which include greenhouse gases¹⁴.
There are advantages to natural gas which include it is cheap to produce and when it is burned it produces mostly carbon dioxide and water vapour so it burns cleaner than coal and oil¹⁴.
Nuclear energy can be considered a renewable energy source but the radioactive element uranium used to produce it is a non-renewable¹⁴. Energy is generated from the energy released when atoms of uranium are split during the process of nuclear fission in a nuclear reactor⁴. The type of uranium used for nuclear energy is U-235 it is used because its atoms are easily split apart¹,¹⁵.
Uranium is a common metal found in rocks worldwide but nuclear energy needs uranium 235 for nuclear fission. Uranium is extracted from rock and then enriched in uranium 235 isotope before being made into pellets that are loaded into assemblies of nuclear fuel rods¹⁶.
The problems with nuclear energy are nuclear reactors are expensive, the power plants used are complex, the production of nuclear energy creates nuclear waste which is extremely toxic and causes many diseases and any leakage of nuclear material can have a devastating effect on the environment¹,⁴.
There are some advantages from nuclear energy as a small amount of radioactive material produces a lot of energy, the raw materials are relatively cheap and last a long time and nuclear power plants do not produce or omit any greenhouse gases¹,⁴.
⁸ https:// www.iea.org/about/faqs/oil/