How Far Does Obama's Clean Power Plan Go in Slowing Climate Change? - Scientific American

Here’s what the Clean Power Plan delivers versus what climate scientists say we need:

Overall Emissions

Clean Power Plan:  Assuming the Clean Power Plan is fully implemented in all 47 affected states, U.S. CO2 emissions just from generating electricity will still add more than 1.7 billion metric tons to the atmosphere each year in 2030—more than the combined emissions of the entire economies of Germany and the U.K. today.

Scientists say:  To avoid 2 degree Celsius of warming the world should restrict total emissions of CO2 to no more than one trillion metric tons before 2050 and not exceed atmospheric concentrations of 450 parts per million.  There are already nearly 600 billion metric tons of extra CO2 in the atmosphere because of fossil fuel burning, forest clearing and other human activities—a number that increases by roughly 50 billion metric tons per year. These figures suggest that pollution must peak before 2020, a full two years before the plan even comes into effect.  Atmospheric CO2 concentrations are already higher than 400 ppm. The cuts included in the plan are a first step but will not be enough to combat climate change.

The Role of Natural Gas

CPP:  Natural gas will become the single largest fuel for electricity generation, and gas-fired power plants will run more often—75 percent of the time, up from roughly 50 percent today. Existing nuclear plants do not help states meet emission-reduction targets.  Only "uprated" or new nuclear power plants, like those under construction in Georgia and South Carolina, can help ensure compliance.  And in case the electricity supply falters, the plan offers exemptions in the form of a so-called "reliability safety valve"—a 90-day period when emissions will not count against a state's reduction goals in the event of emergency, such as extreme weather or a nuclear power plant that must unexpectedly shut down.

Scientists: Natural gas is better than coal—when gas replaces coal as a fuel to generate electricity, CO2 emissions are cut in half—but it still produces CO2 when burned.  And when the methane it contains leaks into the atmosphere, it acts as a potent greenhouse gas itself. When natural gas replaces nuclear power, however, CO2 emissions rise, and cheap natural gas can prevent renewable power from being built in the absence of mandates or other policies.  Natural gas power plants will still be emitting 771 pounds of CO2 per megawatt-hour of electricity at the end of the Clean Power Plan in 2030, adding yet more to the thickening blanket of atmospheric greenhouse gases and potentially slowing the shift to even cleaner forms of electricity generation, such as renewables or nuclear.  "I usually compare natural gas to reduced-fat Oreos," says environmental scientist Steven Davis of the University of California, Irvine.  "They may have less calories than the regular ones but if you are morbidly obese, you should be looking for an apple."

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