Fossil fuels
Natural gas is a fossil fuel. A fossil fuel is a source of energy that was created millions of years ago from fossils. Fossils are calcified plant and animal remains that have been submerged underground for many centuries. Exposure to intense pressures and temperatures have converted them into coal and gas.
Composition
Natural gas is odourless, slightly flammable and non-toxic. It consists of methane, light hydrocarbons such as ethane, propane and butane, and small quantities of derivatives such as carbon dioxide and nitrogen. The precise composition of natural gas differs from region to region.
Groningen gas
Natural gas from Groningen’s Slochteren field is 81% methane, 3.6% higher gaseous hydrocarbons and 0.4% hydrogen sulphide, plus traces of nitrogen and carbon dioxide. Natural gas that is found elsewhere sometimes contains different quantities of methane or more hydrogen sulphide.
