Possible consequences of very large-scale use of unconventional energy sources

Hitherto, unconventional energy sources have been thought of as such minor contributors to the total energy budget that the consequences of their use have had little attention. They will become more important as fossil fuel is used up, if world demand for energy increases, and if power from nuclear fusion does not materialize. It may therefore be useful to consider some possible consequences if unconventional sources were used on a very large scale.