You may say that nuclear power is not really CO2-free and you would be right. But that is also true of wind and solar power. A complete life cycle analysis of energy sources would include CO2 produced when mining for uranium, enriching the
uranium, and making fuel pellets. Similar things are also true of solar and wind. Solar requires a lot of energy and resources to make the solar panels. Wind farms use enormous amounts of concrete for the bases (which requires mining), large amounts of steel for the towers, petroleum products for plastics, and a lot of fuel for constructing the huge wind farms. Numbers vary considerably for these activ­ities, but a range in the amount of CO2 -equivalent greenhouse gases in grams produced for each kWh of energy is 9-21 g/kWh for nuclear, 10-48 for wind, and 100-280 for solar. For comparison, coal produces 960-1,300 and natural gas pro­duces 350-850 g/kWh (6). A conservative estimate is that nuclear power produces about 2% of the CO2 emissions of coal. While the exact numbers are disputed, it is generally agreed that nuclear and wind are similar in CO2 emissions, solar is substantially higher, but they are all much better than coal or natural gas. Because of new technologies for enriching uranium—the step that uses most of the energy and produces most of the CO2—the emissions of CO2 from the nuclear fuel cycle will go down substantially in the future, and nuclear power will be even more important in mitigating global warming (see Chapter 11).