book_cover_big.gifThere is a fierce, ongoing debate between supporters and opponents of using nuclear fission for power plants. The issues are many:  environmental safety, terrorist threats, storage of radioactive waste, depletion of worldwide uranium reserves, and last but not least, the prospect of greatly decreased CO2 emissions. At first glance, most people think that nuclear power plants will not emit CO2 at all, but this is not the case. To perform a truthful analysis, a life cycle analysis must be done¹. In this analysis, the following factors have to be taken into account:

1. Construction of the reactor

2. Operation of the reactor

3. Mining and refinement of uranium

4. Decommissioning the reactor at the end of its lifetime

5. Transporting and storing nuclear waste

Each of these activities will need energy from fossil fuel and other sources, and therefore will generate CO2. For a complete life cycle analysis, we also need to account for the reactor’s operational lifetime, and calculate the amount of uranium present in the ores.

Based on 2004 data from the International Energy Agency (IEA), I believe it is possible to make a rough estimate of how much CO2 is generated by today’s nuclear power plants. In the table below, I have included data from selected industrialized nations that use variable amounts of hydro or nuclear power. We need to look at both data sets together if we want to correlate  energy consumption with CO2 emissions.

Nuclear hydro powertable

Data source: International Energy Agency 2004

For nuclear power, France, Sweden and Ukraine are the top users, and the range runs from almost 80% (France) down to 15% (Canada). The leading users of hydropower  are Norway, Canada and Sweden, and the range here is from 99% (Norway) to 1% (Korea). When we consider both power sources together, we see that these countries use substantial amounts electricity generated from non-fossil fuels, with a range from 99% for Norway to 21% for the United Kingdom.

How does this data allow us to decide whether nuclear power generation is helping to reduce CO2 emissions? Take  a look at the graph below, which plots the CO2 emissions of these nations against the percentage of their non fossil fuel-based electricity generation.

Nuclear power




Data source: International Energy Agency 2004

A few conclusions can be made:

  1. The country with the highest fraction of non- fossil fuel electricity generation (Norway) indeed has the lowest CO2 emission per units of electricity generated.
  2. This correlation seem to hold well for the other countries, except that Ukraine and Russia seem to be outliers. This may be due to less-efficient power plants. Also, Japan is somewhat atypical (on the positive side), perhaps for  the opposite reason (more-efficient generation plants)
  3. The top three nations in hydropower (Norway at 99%, Canada at 57%, and Sweden at 40%) score the lowest in CO2 emission per electricity unit produced². It’s interesting that the number one nation in nuclear power (France, at 78%) is in that same group of low-CO2 performers.

In summary, we can preliminary conclude that both the use of hydropower for electricity generation clearly decreases production of  CO2. However, a complete life cycle analysis (LCA) must be done first before final conclusions can be reached. See for that reference 1.

Later on, I’ll delve a bit deeper into several aspects of using nuclear power for electricity generation.


1. For a detailed discussion, see this article at:

2. I was made aware of a somewhat unexpected source of  CO2 from hydropower generation by  a reader at

Copyright ©2007 John E.J. Schmitz