Coal, oil, and natural gas provide over 85% of the total primary energy used around the world. Although figures differ in various countries, nuclear reactors and hydroelectric power together produce less than 10% of the total world energy. Wind power, active and passive solar systems, and geothermal energy are examples of alternative energy sources. Collectively, these make up the final small fraction of total energy production.

The exact contribution alternative energy sources make to the total primary energy used around the world is not known. Conservative estimates place their share at 3–4%, but some energy experts dispute these figures. Amory Lovins has argued that the statistics collected are based primarily on large electric utilities and the regions they serve. They fail to account for areas remote from major power grids, which are more likely to use solar energy, wind energy,or other sources. When these areas are...