Chemical energy is that which is either released or absorbed when a chemical reaction takes place, such as the release of heat and electrical energy from a hydrogen fuel cell. Another example is the heat release derived from burning wood or other organic substances. Burning represents a commonly relied upon chemical reaction used to release the stored energy in a wide variety of biomass fuels ranging from coal and natural gas to oil and other fossil fuel derivatives.
Chemical bonds store energy and the proper chemical reactions will release that stored energy for human use. Most of the stored energy comes from the sun through photosynthesis, a process of absorption and storing of solar energy in organic mass until it is released through burning. The exploitation of biomass fuel, however, does not come without drawbacks because burning them also produces byproducts which are harmful to the environment.
Burning biomass fuel has produced atmospheric carbon dioxide levels that are higher than what have occurred in 600,000 years. This has led scientists to seek out alternative forms of energy-releasing chemical reactions that can provide for human energy needs without the drawbacks of environmental pollution. Some of the new technologies being explored include the development of improved catalysts for splitting water into hydrogen and oxygen, more efficient battery components and methods that can release energy from biomass fuels through chemical reactions other than burning.