A word about carbon.

There's a widely held belief that renewable and nuclear energy production is 'clean' because it emits no carbon, or at least nothing that wasn't extracted from the atmosphere within the last century or so. Well, that isn't true. A study in 2008 by Benjamin Sovacool at the National University of Singapore calculated the amount of carbon dioxide emitted per kilowatt-hour of electricity generated during the power plant's entire lifecycle, which means that it includes emissions resulting from:

The paper appeared in Energy Policy, vol 36, page 2950. Here is a summary of its findings:

Generator type Carbon dioxide equivalent
emitted (g/kWh)
Emissions relative to a
coal-fired generator
Coal-burning 960 100%
Natural gas [1] 277 28.9%
Nuclear [2] 66 6.9%
Solar photo-voltaic 32 3.3%
Onshore wind farm 10 1%



This figure is not taken from the original paper but was estimated by me. The assumptions I used to calculate the emissions figure are:

  • The energy content of natural gas per tonne is 2.6 times that of coal.
  • Burning a tonne of natural gas emits 75% of the carbon dioxide produced by burning a tonne of coal.

I have further assumed that the construction and decommisioning emissions scale accordingly. This seems reasonable since gas generation plants are considerably smaller and simpler than coal fuelled ones.


Carbon emissions due to uranium mining and refining will rise as the higher quality uranium ore is used up and progressively poorer ores replace them. This assumes that all nuclear electricity generation will continue to be based on natural or low enrichment uranium. In reality uranium fueled reactors will be replaced by MOX, thorium or fast-breeder reactors as uranium reserves are used up.

This may underestimate carbon emissions from uranium-fueled generation: Storm van Leeuwen & Smith estimate nuclear carbon emissions as 1/3 that of natural gas-powered generation, or about 90 g/kWh based on my estimate of gas-powered emissions. This is 9.3% of coal emissions: close enough for Government work.