This week the U.S. Senate is debating the Climate Security Act, a piece of legislation which would require the country to cut its greenhouse gas emissions by 4 percent in 2012, 19 percent in 2020, and 71 percent in 2050 below what they were in 2005. The act rations the emission of greenhouse gases produced by burning fossil fuels by issuing an ever declining supply of emissions allowances. Emitters such as electric power generators, coal, oil and natural gas companies, and energy intensive industries like steel and cement manufacturers will be able to buy and sell the government-issued permits. This trading puts a price on greenhouse gases. The idea is that as energy produced from climate-damaging fossil fuels becomes increasingly expensive, industries, researchers and entrepreneurs will be encouraged to develop new climate-friendly, low-carbon and no-carbon energy technologies. But will this happen?
First, let's consider just how big a technological challenge it will be to cut greenhouse gases by 70 percent. Former General Electric executive Don Dears provides some sense of the size of the challenge when he points out that an 80 percent cut means reducing U.S. carbon dioxide emissions from about 6 gigatons (1 gigaton = 1 billion tons) today to 1 gigaton by 2050. One gigaton is the amount the U.S. emitted around 1920, when there were just 100 million Americans.
Now let's widen the focus to include cuts that the whole world will need to make in order to stabilize concentrations of greenhouse gases in the atmosphere. Currently, the world emits about 26 gigatons of carbon dioxide. In 2007, the International Energy Agency (IEA) projected that by 2030 carbon dioxide emissions will rise by 57 percent to 42 gigatons per year. Climate researchers estimate that in order to stabilize atmospheric concentrations of carbon dioxide at 450 parts per million (ppm) (where there's a good chance that average temperatures would increase by less than 2 degrees Celsius) emissions must be cut by 80 percent from current levels by 2050. This means that the world will have to produce considerably more energy while emitting only 5 gigatons of carbon dioxide annually. If IEA estimates of future energy demand are accurate, this implies that the world would have to find the equivalent of 37 gigatons of carbon-free energy by 2030.
So just how big is a gigaton? Cutting a gigaton of carbon dioxide is equivalent to replacing 1,000 conventional 500-megawatt coal-fired electric generation plants with zero-emission plants. Zero-emission might mean coal-fired plants using carbon capture and sequestration (CCS) technologies, perhaps costing as much as $80 per ton. By some estimates, CCS would increase the cost of producing electricity by 25 to 40 percent. Cutting another gigaton would be equal to building 500 one-gigawatt nuclear power plants. The world currently has 439 nuclear plants in operation. One gigaton more would require increasing the number of windmills operating in the U.S. by 150-fold, or increasing solar photovoltaics by 10,000-fold. It would take farming an area 15-times the size of Iowa to produce the biomass to replace 1 gigaton of carbon dioxide emissions.
The energy technology debate among those who are concerned about the dangers of man-made global warming divides into two camps—wedgists and breakthroughists. Wedgists are deploying the concept of "stabilization wedges" devised by Princeton University researchers Stephen Pacala and Robert Socolow. They define a stabilization wedge as the reduction of carbon dioxide emissions by 1 billion tons of carbon per year by mid-century (1 billion tons of carbon is equivalent to 3.7 billion tons of carbon dioxide). In their analysis, each wedge of reductions is achieved using already commercialized technology, generally at much larger scale than today. The goal is for the world to emit no more greenhouse gases than we do today by mid-century and then steeply cut emissions to near zero in the last half of the 21st century.
Some proposed stabilization wedges include increasing the fuel economy for 2 billion cars from 30 to 60 miles per gallon (mpg); decreasing car travel for 2 billion 30-mpg cars from 10,000 to 5000 miles per year; deploying 2 million one-megawatt windmills occupying 74 million acres; building 700 one-gigawatt nuclear power plants; installing 2000 gigawatts of photovoltaic power on 5 million acres; and planting more than 600 million acres with biofuel crops.
Breakthroughists argue that the wedgist approach is a technical and political non-starter. In 2002, a number of leading energy researchers argued in Science that current on-the-shelf technologies cannot supply low-carbon energy at an acceptable cost. One of the co-authors, MIT engineer Howard Herzog, declared, "To reduce greenhouse gas emissions from our energy systems while maintaining energy prices at comparable levels to today will take revolutionary change as opposed to evolutionary change."
More recently, passionate breakthroughists like Ted Nordhaus and Michael Shellenberger claim that studies show that carbon dioxide emissions would have to be priced at around $100 per ton between 2010 and 2030, rising to $160-200 per ton between 2030 and 2050, to achieve deep cuts in U.S. greenhouse gas emissions by 2050. Thus they argue that the wedgists are framing the energy challenge "as a forced choice between poverty and environmental ruin. With a choice like that, it is no surprise that the world has failed to make real strides towards a cleaner energy future." They add, "If policymakers limit greenhouse gases too quickly, the price of electricity and gasoline will rise abruptly, triggering a political backlash from both consumers and industry."
Breakthroughists point out that polls regularly find that people around the world are unwilling to pay much more for green energy. In addition, higher energy prices would mean that more than a billion poor people in developing countries will have to wait even longer to gain access to modern fuels.
So breakthroughists Nordhaus and Shellenberger are proposing "a ten-year, $300 billion public investment into accelerating the transition to a clean energy economy. The goal of the program is to bring the price of clean energy down to the price of coal and natural gas as quickly as possible." Even breakthroughists agree that the price of energy produced using fossil fuels must increase at least somewhat in order to encourage energy suppliers to switch to whatever new breakthrough technologies are developed. Wedgists like Climate Progress editor Joseph Romm dismiss such breakhthroughist proposals as wishful thinking. Romm asserts that ramping up energy supply breakthroughs would take decades and that the climate change problem is too urgent to wait for such breakthroughs to emerge.
Although the Climate Security Act does direct some spending towards low-carbon energy research, it is basically a wedgist scheme. If something like it is adopted by the next presidential administration, we will find out which side is right. If the wedgists are correct, cutting carbon dioxide emissions will produce a modest increase in energy prices resulting in the deployment of a wide variety of readily available low-carbon energy sources over the coming decades. If the breakthroughists are right, energy prices will soar provoking a political backlash. In which case, perhaps one need only peer across the Atlantic to the spreading protests against higher fuel prices in Europe to see the future.
Ronald Bailey is reason's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books.