COAL: The fuel associated with the industrial revolution remains a key energy staple. Hard coal production worldwide has increased by 65% over the last quarter of a century. Proven reserves are abundant and estimated to last 164 years - considerably longer than oil or gas. Coal supplies over 24% of global primary energy needs, and is the largest single source of the world's electricity (40%). However it also produces more greenhouse gas emissions for the energy it gives than any other major fuel.
OIL: Although known from early times, it was not used a fuel until recently. But since the development of the refining process and the start of commercial drilling some 150 years ago, it has come to assume a central place in the global economy. Apart from fuelling vehicles, aircraft and ships, and heating homes and businesses, it is also a source of raw material for plastics, chemicals, fertilizer and fabrics. It is used for 6.9% of electricity generation. Oil prices hit new highs in 2005 amid instability in areas where most oil is extracted, along with signs that supplies may be running down.
GAS: Natural gas is found in pockets on its own, or in oil or coal deposits. Environmentally, it burns more cleanly than oil and coal and produces less carbon dioxide, the principal greehouse gas, than either. Its contribution to the total primary energy demand is projected to rise to 25% by 2030. It is a major source for electricity generation and industrial production. Compressed and liquefied gas are also used as a vehicle fuel.