In 2005 Amory Lovins of the Rocky Mountain Institute in Snowmass CO, USA showed that the output of decentrallised, low-carbon power sources has caught up with the world's nuclear generation capacity and is predicted to overtake it during 2006. This is the first time that the combined output of small-scale generators has been calculated. The study included non-biomass decentrallised cogeneration (60%-70% natural gas fuelled) together with geothermal, photovoltaic, biomass, small hydro and wind generation. Small hydro excludes schemes with outputs of over 10 MW. Fossil fuelled cogeneration accounts for 72% of this capacity and renewables for 28%.
This study predicts that by 2010 renewables are expected to be producing 45% as much electricity as the nuclear generators.
The renewable energy sources divide into seven categories: