Introducing 700 GWe of nuclear power by 2055 would yield another wedge of C02 reduction. This is about double the total nuclear capacity deployed today. While the public is becoming less opposed to nuclear power, serious concerns remain about safety, waste disposal, and proliferation. The wind turbine generating capacity is currently about 40 GWp, which corresponds to about 14 GW continuous power, assuming a capacity factor of This would need to increase by 50 times over the next 50 years to produce another wedge. There has been public opposition to siting wind farms in some areas due to their effect on the landscape and on the bird population. There is a strong case to be made that we should accept a relatively short-term disadvantage (wind turbines could be easily fully dismantled at the end of their use) because of the serious need to take action that will help everyone now.
Solar power could also make a wedge but there is currently only about 3 GWp of photovoltaic (PV) power installed. In very sunny locations a capacity factor of close to a third can be realized, though generally it is closer to 10-20%. PV has considerable potential, particularly in rural areas, as well as being integrated in new buildings. Geothermal power would need to expand by about a factor of 100 to provide a further wedge. There are considerable reserves of geothermal energy and it can be used both on a large scale and on a domestic scale using heat pumps to provide more efficient heating and cooling of buildings.
Currently, nearly all the world’s transport uses fossil-based fuels. Biomass can be used to produce ethanol or biodiesel, but this requires huge land areas to produce a significant amount. Pacola and Socolow estimate that 250 million hectares would be required to produce one wedge. This is three-quarters of the size of India! An alternative would be to use hydrogen, which could be produced using nuclear power or fossil-fuel based power with carbon capture and storage (CCS). The hydrogen would then be used in fuel-cells in cars and trucks. Reducing the CO2 emissions from vehicles and planes is of major importance. It would be easier to produce sufficient biofuel for planes, as they use less than vehicles. Furthermore, there is no simple alternative fuel.