Comparisons of life-cycle greenhouse gas emissions attempt to calculate the emissions of greenhouse gases or solely carbon dioxide over the full life of a power source, from groundbreaking to fuel sources to waste management back to greenfield status.
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A meta analysis of 103 life cycle studies by Benjamin K. Sovacool, found that fossil fueled power plants produce electricity with about 443-1050 g equivalent lifecycle carbon dioxide emissions per kWh, nuclear power plants produce electricity with about 66 g (no range given) equivalent lifecycle carbon dioxide emissions per kWh, and renewable power generators produce electricity with 9.5-38 g carbon dioxide per kWh.[1]
Nuclear energy technologies are thus seven to sixteen times more effective than fossil fuel power plants on a per kWh basis at fighting climate change, and renewable electricity technologies are "two to seven times more effective than nuclear power plants on a per kWh basis at fighting climate change". Such estimates already include all conceivable emissions associated with the manufacturing, construction, installation and decommissioning of renewable power plants.[2]
| Technology | Description | Estimate (g CO2/kWhe) |
|---|---|---|
| Wind | 2.5 MW offshore | 9 |
| Hydroelectric | 3.1 MW reservoir | 10 |
| Wind | 1.5 MW onshore | 10 |
| Biogas | Anaerobic digestion | 11 |
| Hydroelectric | 300 kW run-of-river | 13 |
| Solar thermal | 80 MW parabolic trough | 13 |
| Biomass | various | 14-35 |
| Solar PV | Polycrystaline silicon | 32 |
| Geothermal | 80 MW hot dry rock | 38 |
| Nuclear | various reactor types | 66 |
| Natural gas | various combined cycle turbines | 443 |
| Diesel | various generator and turbine types | 778 |
| Heavy oil | various generator and turbine types | 778 |
| Coal | various generator types with scrubbing | 960 |
| Coal | various generator types without scrubbing | 1050 |
A 2007 report published by the Oxford Research Group listed the following results: coal = 755 g/kWh; natural gas = 385 g/kWh; biomass = 29 - 62 g/kWh; wind = 11 - 37 g/kWh; nuclear = 11 - 130 g/kWh (using the minimum and maximum results amongst 3 studies). The report concluded that "Emissions from nuclear power lie somewhere between biomass and natural gas ... Furthermore, as the available average ore grade declines CO2 (and other Greenhouse Gases) emissions from nuclear power will increase." [3]
In terms of individual studies, a wide range of estimates are made for many fuel sources which arise from the different methodologies used. Those on the low end tend to leave parts of the life cycle out of their analyses, while those on the high end often make unrealistic assumptions about the amount of energy used in some parts of the life cycle.[5]
The Intergovernmental Panel on Climate Change states that total life-cycle GHG emissions per unit of electricity produced from nuclear power are below 40 gCO2-eq/kWh (10 gC-eq/kWh), similar to those for renewable energy sources. [6]
A study of life-cycle emissions by Swedish utility Vattenfall reported that nuclear power produced 3.3 g CO2/kWh, wind power produced 10, natural gas produced 400 and coal 700.[4]
Another report - Life-Cycle Energy Balance and Greenhouse Gas Emissions of Nuclear Energy in Australia - conducted by the University of Sydney in 2008 produced the following results: nuclear = 60-65 g CO2/kWh; wind power = 20 g/kWh; solar PV = 106 g/kWh. Furthemore, the study criticised the Vattenfall report : "it omits the energy and greenhouse gas impacts of many upstream contributions".[7]
In a study conducted in 2006 by the UK's Parliamentary Office of Science and Technology (POST), which used figures from the Torness study[8], nuclear power's life cycle was evaluated to emit the least amount of carbon dioxide (very close to wind power's life cycle emissions) when compared to the other alternatives (fossil fuel, coal, and some renewable energy including biomass and PV solar panels). [9]
A 2005 study[10], issued by stormsmith, reported that carbon dioxide emissions from nuclear power plants per kilowatt hour could range from 20% to 120% of those for natural gas-fired power stations depending on the availability of high grade ores.[10]