Ron Bailey of Reason, reporting from Bali, has an interesting post up summarizing the discussion by James Connaughton, director of President Bush's Council on Environmental Quality, on one small aspect of the climate conundrum, namely, what would be actually involved in meeting the energy shortfall implict in targets to reduce CO2 emissions by half by mid-century.
Connaughton offered an interesting thought experiment. The major economies emit 22 gigatons (1 billion tons) of CO2 annually. In one reference case, those emissions would rise to 37 gigatons by 2050. So, Connaughton says, assume that we need to reduce current emissions by half from current emission—by 11 gigatons—to stabilize CO2 atmospheric concentrations. That means that the world would have to find the equivalent energy that producing 25 gigatons of emissions would have produced in 2050.
To get a handle on what this might mean, Connaughton asked, "How big is a gigaton?" One gigaton is equivalent to 273 coal-fired electric generation plants with carbon capture and sequestration (CCS). Of course, there are only a few demonstration plants now, and 273 plants represent 7 percent of the world's current coal-fired generation capacity. Estimates of how much CCS might cost range between $150 to $250 per ton of carbon (or $50 to $80 per ton of CO2). By one estimate CCS would raise the cost of electricity to 25 to 40 percent; others suggest that the increase could be as much as 85 percent.
Connaughton also pointed out that avoiding the emission of a gigaton of CO2 implies building 135 new nuclear power plants. The world has 400 now. In addition, a gigaton is equivalent to 270,000 windmills which is 4-times more than are currently operating. Growing enough biofuels to reduce a gigaton of emissions would take an area twice the size of the United Kingdom. Of course, such projections rely on the deployment of near-term technologies. It's impossible to tell what new technologies a higher price on carbon fuels might call forth from the world's laboratories.