Energy

Low Carbon Future?

It's harder than you think

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Buenos Aires—"To stop further damage to the climate we need a worldwide 60% reduction in emissions by 2050," declared British Prime Minister Tony Blair in February 2003. Set aside the question of how likely we are to see catastrophic climate change brought on by extra greenhouse gases (GHG). Is Blair's goal feasible?

A report released here at the United Nations Conference on Climate Change shows that achieving such steep reductions is probably impossible. The report, from the World Business Council for Sustainable Development (WBCSD), assumes a goal of stabilizing carbon dioxide in the air at 550 parts per million (ppm) by 2050. The current level is 380 ppm. The report further assumes that the poorest people on the planet will want to enjoy the higher levels of prosperity that come from economic growth fueled by access to energy supplies.

Presented by two oilmen, Shell International climate change manager David Hone and British Petroleum climate change manager Mark Akhurst, the report outlines what it would take to attain those goals. Hone and Akhurst base their analysis on economic and GHG emission storylines devised by the Intergovernmental Panel on Climate Change's (IPCC) Third Assessment Report. Those storylines assumed that carbon emissions would reach about 14 gigatons (14 billion tons) annually by 2050. Humanity currently emits about 22 gigatons of carbon dioxide, about seven gigatons of which is carbon (excluding traditional biomass burning of one gigaton). That 22-gigaton annual output of carbon dioxide comes from burning about seven gigatons of the current mix of hydrocarbon.

To keep from building up carbon dioxide to more than 550 ppm in the atmosphere by 2050, no more than the current 7 billion tons annually should be emitted. In the WBCSD report, Hone and Akhurst claim that the goal of doubling world energy supplies while emitting only 7 gigatons of carbon by 2050 can be accomplished using technologies now available.

Although they differ in some details, the WBCSD report relies a good bit on the analysis published in Science by Princeton University engineering professor Robert Socolow and his colleagues. Both use the concept of technological 'wedges" which, when fully deployed in 2050, will result in one gigaton per year of carbon emissions reductions. Hone and Akhurst stress that major technological transitions take a long time to implement: There are no quick, easy and cheap ways to reduce carbon dioxide emissions. To illustrate the point they offer a scenario in which some type of zero-emissions vehicle becomes available in 2010. Beginning with the deployment of 200,000 such vehicles, and assuming market growth at a very unrealistic 20 percent per year, it would take until 2050 before such vehicles outnumbered conventional vehicles.

As an outlandish thought experiment, Hone sketched out a scenario in which all new power generation facilities emitted no carbon dioxide from now on, e.g., use only nuclear power, renewables, and coal power that somehow sequestered the carbon dioxide (perhaps by pumping it into empty oil reservoirs). When would carbon emissions begin to decline? In about 30 years. Why? Because the old power plants would still continue to emit before they aged out and were replaced.

Let's take a look at some of what it would take to achieve the WBCSD goal of stabilizing concentrations of carbon dioxide in the atmosphere over the next 50 years. First, new low carbon technologies would need to begin being deployed almost immediately. To reduce projected emissions by one gigaton per year in 2050, the world would have to build 1400 new one-gigawatt combined cycle gas turbine power plants to replace coal-fired plants. A gigawatt is enough electricity to power about 400,000 homes. That translates into a growth rate of 2.6 percent per year or building two new gas power plants per month for the next 50 years. The International Energy Agency projects a 2.4 percent rate of growth through 2030.

To avoid another gigaton of carbon emissions by 2050, would require building 700 one-gigawatt nuclear power plants rather than the equivalent conventional coal facilities. That means that the rate of growth in nuclear power generation needs to be 4 percent per year rather than the current 2.5 percent. One more gigaton of emissions could be cut if the world's projected 2 billion vehicles in 2050 got 60 miles rather than 30 miles to the gallon. Another could be curtailed by 300,000 five-megawatt wind turbines. Of course, the wind turbines would be need to be deployed in an area the size of Portugal and five-megawatt wind turbines are only prototypes now. Biofuels derived from 250 million hectares of high yield crops could avoid another gigaton of carbon emitted per year in 2050. This would mean that a sixth of the world's current cropland would be devoted to producing fuel. That can't be good for biodiversity. And building 700 coal-fired one-gigawatt power stations using carbon dioxide capture and storage would cut one gigaton of carbon. Akhurst pointed out that no low-cost carbon dioxide separation technology currently exists and that carbon capture and storage facilities would be nearly the same size as the power plant. The remaining two gigatons can be avoided by a combination of increased energy efficiency in appliances and buildings, more mass transit, and some societal changes.

Finally, the WBCSD study included a possible fuel mix for the world in 2050 in which the world's power supply is doubled and emits nine gigatons of carbon per year. In that scenario, the world will need the equivalent of 3,000 one-gigawatt natural gas-fired power plants, 1,000 one-gigawatt coal-fired plants, 1,000 one-gigawatt coal-fired plants with carbon capture, 1.5 million five-megawatt windmills, 2,500 nuclear power stations, 2,000 hydropower stations, 65 exajoules of solar power, 1 billion high fossil-fueled vehicles, and 1 billion biofueled vehicles, 50 exajoules of biofueled heating and cooling and 250 exajoules of fossil fueled heating and cooling. An exajoule is equivalent to approximately 23.5 million metric tons of oil.

Currently, humanity is fueled by 1,000 one-gigawatt coal-fired power plants, 400 one-gigawatt oil-fired plants, 250 gas-fired plants, 350 nuclear power stations, 500 gigawatts of hydropower, 750 million fossil-fueled vehicles, 130 exajoules for heating and cooling, 50 exajoules from the burning of traditional biomass.

Doing the math, in order to double the world's energy supplies over the next 50 years, the world will need to build, among other things: the equivalent of 2,750 new one-gigawatt natural gas-fired power stations; 1000 new coal-fired one-gigawatt power plants with carbon capture; 1.5 million windmills deployed over a bit less than 300,000 square miles; 2,150 new nuclear plants; 1,500 new one-gigawatt hydropower stations, not to mention new solar and biofuel technologies.

Recall that Blair and others are calling for emission reductions of 60 percent by 2050. That would mean that instead of emitting seven gigatons of carbon in 2050 under the WBCSD scenario, the world would emit only 2.8 gigatons of carbon annually. As the old saying goes, it may be that 'you can't there from here."