ABSTRACT
Fossil fuels are inevitably going to run out one day. Coal reserves seem very high, but the proximity of peak oil is a subject of discussion. We won’t always be able to extract more oil than we did the year before. Many authors are concerned about this, considering the economy’s dependence on oil. Uranium resources needed for nuclear power are not worrying for the moment; moreover other nuclear technologies exist and could increase the reserves tenfold. The potential of renewable energies is difficult to assess: solar, wind, wood, hydroelectricity, geothermal energy, etc., require large areas or suitable geographical sites. Their ratio of “energy returned on energy invested” is quite low. This ratio is a fundamental and largely neglected parameter. Renewable energies require more concrete, copper, aluminium and steel than nuclear and fossil fuels.
