Energy use is a fundamental component of human development. Whether for cooking, heating or lighting, fuel for motor vehicles, power for TV or radio, for basic survival or economic development - to varying degrees we all use energy.

Energy sources fall broadly into two categories:

 - Those for which there are limited resources - classed as finite energy sources, often referred to as "conventional energy sources" (mainly fossil fuels such as coal, oil and gas).

- Those which will never be exhausted - renewable energy sources (solar, wind, hydro, biofuels, energy from the oceans and geothermal).

Finite resources

Finite energy sources - mainly coal, oil and gas - were formed over a period of millions of years by the action of heat and pressure on organic matter (dead plant and animal material). They tend to have high energy densities - i.e. have a high energy content in a relatively compact form - which has led to their extensive use over the last few hundred years to drive forward industrialization and development around the world.

Eventually, depending upon the rate at which we use these fuels, there will come a time when the resources run out. At current rates of use, coal reserves will still last for several hundred years, while oil and gas reserves are expected to be sufficient to last well into this century. However, their depletion - and the need to identify alternatives to take their place - is only one of the issues associated with finite energy sources; a more immediate problem associated with fossil fuel usage is that it gives rise to emissions of gases which can contribute to air pollution, causing problems like acid rain and smog, and climatic changes on a global level - the "greenhouse effect". The precise impact that the greenhouse effect will have on our environment is unclear and difficult to predict, but current consensus is that more extreme climate variations and weather patterns are likely, which may result in more incidents of drought, flood and severe winds. The impact of these climatic effects are expected to be increased crop failures, famine and damage to property.

Renewable energy alternatives

Renewable energy (RE) sources, sometimes referred to as alternative energy sources, will never be exhausted and their use does not present the environmental problems associated with fossil fuels.

RE sources include wind, solar (photovoltaic or thermal), hydro and ocean energy (wave, current or tidal) and sustainable biofuels. Geothermal energy is normally also categorized under the renewable energy umbrella. It is also possible to combine one or more renewable energy technologies (e.g. wind and/or solar photovoltaic) with a conventional energy technology (e.g. a diesel generator). This arrangement is know as a hybrid system.

This area provides an introduction to each of these technologies and presents an indication of their current application and future potential contribution to China's considerable energy needs.