Fossil fuels are formed by the anaerobic decomposition of remains of organisms including phytoplankton and zooplankton that settled to the sea (or lake) bottom in large quantities under anoxic conditions, millions of years ago.
Fossil fuels are oil, coal and natural gas. In 2006 primary sources of energy consisted of petroleum 36.8%, coal 26.6%, and natural gas 22.9%, amounting to an 86% share for fossil fuels in primary energy production in the world.
Crude oil is a smelly, yellow-to-black liquid and is usually found in underground areas called reservoirs. Scientists and engineers explore a chosen area by studying rock samples from the earth. Measurements are taken, and, if the site seems promising, drilling begins.
Coal is a readily combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds.
Natural gas is a gas consisting primarily of methane. It is found associated with fossil fuels, in coal beds, as methane clathrates, and is created by methanogenic organisms in marshes, bogs, and landfills.
Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being formed.
All fossil fuels are made of hydrocarbons. Hydrocarbons store energy in the form of the atomic bonds. Energy stored in hydrocarbons can be released very easy - we just have to burn them.
When fossil fuels are burned carbon and hydrogen react with oxygen in air to carbon dioxide (CO2) and water (H2O). During this reaction heat is released which further amplifies the reaction.
One of the biggest benefits of fossil fuels is their cost. Coal, oil and natural gas are abundant right now and relatively inexpensive to drill or mine for.
At current usage, the coal supply will last 1500 years. However at a 5% growth rate the coal supply will last only 86 years. We can expect even greater usage as other fossil fuels become scarce.
Coal energy yield depends on how much carbon is contained in it. Two types dominate US reserves. Anthracite is 95% carbon and is approximately 300 million years old. Lignite is 25% carbon is nearly 150 million years old.
To run a 100-watt light bulb 24 hours a day for a year we need to use about 714 pounds (325 kg) of coal in coal powered power plant (thermal efficiency of such power plant is typically abut 40%).
Fossil fuels are also overwhelmingly responsible for fueling our transportation system. Petroleum-based fuels are the standard.
One liter of regular gasoline is the time-rendered result of about 23.5 tonnes of ancient organic material deposited on the ocean floor.
The total fossil fuel used in the year 1997 is the result of 422 years of all plant matter that grew on the entire surface and in all the oceans of the ancient earth.
Burning fossil fuels is responsible for environmental issues that are high on the political agenda these days. Examples are greenhouse gas accumulation, acidification, air pollution, water pollution, damage to land surface and ground-level ozone.