Fossilfuel

Fossil fuels are energy resources formed from ancient organic matter that, over geological timescales, was buried and transformed by heat and pressure. The three most widely used fossil fuels are coal, crude oil, and natural gas. They are nonrenewable on human timescales.

Formation: Coal forms from terrestrial vegetation in swampy environments; petroleum and natural gas originate mainly from marine microscopic organisms. Conditions such as burial depth, temperature, and pressure determine the type and quality of the fuel. They are typically found in porous rock formations capped by impermeable layers.

Uses and production: Fossil fuels have broad uses in electricity generation, transportation, heating, and industrial processes. Coal is mined and burned for power and industry; crude oil is refined into fuels, lubricants, and petrochemicals; natural gas is used for heating, electricity, and as a chemical feedstock. Extraction and refining involve drilling, mining, pipelines, and shipping.

Environmental and health impacts: Combustion releases greenhouse gases, notably carbon dioxide and methane, contributing to climate change. It also emits sulfur dioxide, nitrogen oxides, and particulates that affect air quality and human health. Extraction, processing, and transport can cause oil spills, habitat disruption, and water and soil contamination.

Reserves and transition: Global fossil-fuel reserves are finite and unevenly distributed, with ongoing debates about future supply and price. Many governments and organizations promote reduced emissions and a transition to low-carbon energy, including renewables and energy efficiency; policy instruments include carbon pricing, subsidies, and regulations. The pace and mix of transition vary by region.