Last December’s agreement in Bali to launch a two-year negotiation on climate change was good news, a rare example of international cooperation in a world seemingly stuck in a spiral of conflict. Cynics might note that the only accomplishment was an agreement to talk some more, and their cynicism may yet be confirmed. Nevertheless, the growing understanding that serious climate-control measures are feasible at modest cost is welcome.
The arithmetic is becoming clearer. If the rich nations continue to grow in wealth and the poor ones systematically narrow the income gap with successful development, by 2050 the global economy might increase sixfold and global energy use roughly fourfold. Today’s anthropogenic carbon dioxide (CO2) emissions are around 36 billion tons annually, of which 29 billion are the result of fossil-fuel combustion and industrial processes, and another seven billion or so are to the result of tropical deforestation. Roughly speaking, every 30 billion tons of emissions raises CO2 levels by around two parts per million (ppm). The current atmospheric concentration of CO2 is around 380 ppm, up from 280 ppm at the start of the industrial era in 1800. Thus, to arrive at 430 to 450 ppm by 2050—a plausibly achievable “safe” level in terms of its likely climate change consequences, but only 50 to 70 ppm more than the current one—cumulative emissions should be kept to roughly 750 to 1,050 billion tons, or roughly 20 billion tons a year. This goal can be achieved by ending deforestation (on a net basis) and cutting by one third our current fossil-fuel-based emissions.
So here is the challenge. Can the world economy use four times more primary energy while lowering emissions by one third?
The key, arithmetically, is to cut CO2 emissions per unit of primary energy to roughly one-sixth of their current level. That may sound like a daunting task, but it is actually within reach. Let’s remember that 80 percent or so of total energy use will come from a small number of types of sources: electricity production (40 percent), vehicles (25 percent), heavy industries including cement, petrochemicals, refining, and steel (10 percent), and heating of buildings (10 percent).
A promising core strategy seems to be the following. Electricity needs to be made virtually emission-free, through the mass mobilization of solar and nuclear power and the capture and sequestration of carbon dioxide from coal-burning power plants. With a clean power grid, most of the other emissions can also be controlled. In less than a decade, plug-in hybrid automobiles recharged on grid will probably get 100 miles per gallon. Clean electricity could produce hydrogen for fuel-cell-powered vehicles and replace on-site boilers and furnaces for residential heating. The major industrial emitters at refineries, cement plants, and steel mills could be required (or induced through taxation) to capture their CO2 emissions or to convert part of their processes to run on power cells and clean electricity.
The economics are also favorable. Carbon capture and sequestration at coal-fired power plants might raise costs for electricity as little as one to three cents per kilowatt-hour, according to a special report of the Intergovernmental Panel on Climate Change. The mass conversion of the U.S. to solar power might involve an incremental cost of roughly four cents per kilowatt-hour, with overall electricity costs on the order of eight to nine cents per kilowatt-hour. These incremental costs imply far less than 1 percent of the world’s annual income to convert to a clean power grid. The costs in the other sectors will also be small. The fuel savings of low-emissions cars could easily pay for the added costs of batteries or fuel cells. Residential heating by electricity (or co-generated heat) rather than by home boilers will generally yield a net saving, especially when combined with improved insulation.