What if we told you that in order to feed that light bulb that you leave on, in your office, 2 hours a day, 7 days a week, are necessary 800 kilos of coal? Or that, to produce the gas litter, used yesterday, took 26 tons of raw oil?

Fossil fuels, like coal and oil, as well as rock fossils, are formed by dead plants and animals. These non-renewable energy sources currently supply about 80% of world energy. They generate electricity and heat, and they move transportation, besides feeding manufacturing processes of various products, from steel to plastic.

When fossil fuels are burnt, they release carbon dioxide (CO2) and other greenhouse effect gases (GEG), that’ll retain heat in the atmosphere, being primarily liable for global warming and climate change.

Climate Works Foundation tells us that, from 1850 to 2019, 2.400 gigatons of CO2 were issued through human activity. Around 950 gigatons were released into the atmosphere. The remaining was absorbed by the oceans and the Earth.

What are fossil fuels after all?

Coal

Coal started forming during the Carboniferous period (360 to 290 million years) when in swampy forests, deeper under the mud, layers of seaweed and vegetation debris started being deposited. Depending on their level of carbon, it’s classified into four categories: coal anthracite, bituminous, sub-bituminous, and lignite.

It provides a third of all the energy in the world. CO2 emissions are induced by the burning of coal, representing 44% of the world's total (data from the World Nuclear Association). This activity is the main responsible for the rise in global temperature above the pre-industrial levels.

The consequences for health and the environment of the use of coal, as well as the growing competition for cheap natural gas, have been granting for the demise of this energy source in several western countries.

Oil

A great part of oil was formed during the Mesozoic period (252 and 66 million years), when plankton, seaweed, and other materials ended up buried deep underwater. Raw oil, composed primarily of carbon and hydrogen, is extracted from terrestrial and water wells, and later refined into a variety of oil products, including gasoline, diesel, and heating oil. According to released data by BBC, the USA, Saudi Arabia, and Russia, together, are responsible for nearly 40% of the world supply.

National Geographic points towards the use of oil as responsible for nearly half of the carbon emissions in the USA and around a third of the global total. Besides atmospheric pollution, induced by the burning of oil, its perforation and transportation originated serious accidents with severe consequences, such as the ones that happened at the time of cargo vessel spillage Exxon Valdez (1989) and Prestige (2002); or the problems occurring in the Deepwater Horizon platform (2010), besides the thousand of incidents in oil pipelines.

Still, supplied by the growing desire for motility and the production of items that require petrochemicals, usually derived from oil and gas, the search for oil keeps growing.

Natural gas

It concentrates, usually, in deposits, such as coal and oil, which have formed for millions of years, from the decomposition of vegetable materials and organisms. Composed primarily of methane, it’s odorless and is the cleanest fuel than coal and oil, when it comes to emissions.

According to the European Commission, it represents a fifth of the total world emissions, without counting the so-called fugitive emissions. Not all the worldwide natural gas emissions are being actively extracted. Underwater methane hydrates, for example, where gas is trapped under frozen water, are being faced as a prospective resource of gas.

Powered by the progress in perforation techniques, natural gas production has increased in the last two decades. The USA is the world leader in natural gas production, followed by Russia and Iran.

Reduction of fossil fuels emissions

Governments all over the world are now committed to reducing the emissions of greenhouse effect gases induced by fossil fuels, to avoid the more worrying effects of climate change.

Committed to the goal for the reduction of emissions, undertaken individually, or resulting from the Paris Agreement (2015), governments concentrate efforts having in mind the replacement of fossil fuels for renewable energy sources.

Many sources of carbon emissions, like the electric power plants, that work with natural gas and coal, are being shut down a little at a time, all over the world. Considering the continuous world dependence on fossil fuels, the need to resort to technology is also defended, by capturing carbon from the air and deviating emissions to underground storage or recycling.

It’s already undergoing, several projects to capture carbon dioxide from mill chimneys that resort to fossil fuels. Although the increasing cost inherent to this capture is preventing their application in a more generalized way, it’s expected that technological advances end up turning this into a more accessible solution.