Alternative energy is an umbrella term that refers to any source of usable energy intended to replace fuel sources without the undesired consequences of the replaced fuels.
The term "alternative" presupposes a set of undesirable energy
technologies against which "alternative energies" are contrasted. As
such, the list of energy technologies excluded is an indicator of which
problems the alternative technologies are intended to address.
Controversies regarding dominant sources of energy and their
alternatives have a long history. The nature of what was regarded
alternative energy sources has changed considerably over time, and
today, because of the variety of energy choices and differing goals of
their advocates, defining some energy types as "alternative" is highly
In a general sense in contemporary society, alternative energy is
that which is produced without the undesirable consequences of the
burning of fossil fuels, such as high carbon dioxide emissions, which is considered to be the major contributing factor of global warming according to the Intergovernmental Panel on Climate Change. Sometimes, this less comprehensive meaning of "alternative energy" excludes nuclear energy (e.g. as defined in the Michigan Next Energy Authority Act of 2002).