Fossil fuel

A fossil fuel is a fuel formed by natural processes, such as anaerobic decomposition of buried dead organisms, containing energy originating in ancient photosynthesis.Such organisms and their resulting fossil fuels typically have an age of millions of years, and sometimes more than 650 million years.Fossil fuels contain high percentages of carbon and include petroleum, coal, and natural gas.Commonly used derivatives of fossil fuels include kerosene and propane.Fossil fuels range from volatile materials with low carbon-to-hydrogen ratios (like methane), to liquids (like petroleum), to nonvolatile materials composed of almost pure carbon, like anthracite coal.Methane can be found in hydrocarbon fields either alone, associated with oil, or in the form of methane clathrates. The theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the Earth's crust over millions of years was first introduced by Andreas Libavius 'in his 1597 Alchemia ' and later by Mikhail Lomonosov 'as early as 1757 and certainly by 1763'. The first use of the term 'fossil fuel' occurs in the work of the German chemist Caspar Neumann, in English translation in 1759. The Oxford English Dictionary notes that in the phrase 'fossil fuel' the adjective 'fossil' means 'btained by digging; found buried in the earth', which dates to at least 1652 - before the English noun 'fossil' came to refer primarily to long-dead organisms in the early 18th century. As of 2017 the world's primary energy sources consisted of petroleum (34%), coal (28%), natural gas (23%), amounting to an 85% share for fossil fuels in primary energy-consumption in the world.Non-fossil sources as of 2006 included nuclear (8.5%), hydroelectric (6.3%), and others ( geothermal, solar, tidal, wind, wood, waste) amounting to 0.9%.World energy-consumption was growing at about 2.3% per year. As of 2015 about 18% of worldwide consumption came from renewable sources. Although natural processes continually form fossil fuels, such fuels are generally classified as non-renewable resources because they take millions of years to form and the known viable reserves are being depleted much faster than new ones are being made. The use of fossil fuels raises serious environmental concerns.The burning of fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO2) per year.It is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year.Carbon dioxide is a greenhouse gas that increases radiative forcing and contributes to global warming.A global movement towards the generation of low-carbon renewable energy is underway to help reduce global greenhouse-gas emissions. Aquatic phytoplankton and zooplankton that died and sedimented in large quantities under anoxic conditions millions of years ago began forming petroleum and natural gas as a result of anaerobic decomposition. Over geological time this organic matter, mixed with mud, became buried under further heavy layers of inorganic sediment. The resulting high levels of heat and pressure caused the organic matter to chemically alter, first into a waxy material known as kerogen which is found in oil shales, and then with more heat into liquid and gaseous hydrocarbons in a process known as catagenesis. Despite these heat driven transformations (which may increase the energy density compared to typical organic matter), the embedded energy is still photosynthetic in origin. Terrestrial plants, on the other hand, tended to form coal and methane. Many of the coal fields date to the Carboniferous period of Earth's history. Terrestrial plants also form type III kerogen, a source of natural gas.