The development of potentially enormous new natural gas deposits in the U.S. has revived an old idea for cleaning up America’s power sector: using natural gas a low-carbon bridge from dirty coal to clean renewable power. What makes the idea enticing is that we don’t need to build much new infrastructure to significantly reduce carbon emissions. According to Geoffrey Styles, we already have an enormous amount of gas-powered generation capacity just lying around unused:
Capitalizing on shale gas to take a big bite out of US GHG emissions would depend on two key facts: First, gas-fired power plants emit on average 37% less CO2 than coal-fired plants. At the same time, although the US generated more than twice as much electricity from coal as from gas last year, we actually have more gas-fired generating capacity than coal-fired. The former is merely utilized less–an average of 25% of the time, compared to 73% for coal — for reasons that made perfect sense in a world in which CO2 emissions didn’t matter. If we doubled our utilization of existing gas-fired power plants and burned correspondingly less coal, the country would emit roughly 330 million fewer tons of CO2 per year, representing about 13% of the emissions from the power sector, or a reduction of a bit more than 5% of all US net emissions. And that’s probably a conservative estimate, since the best combined-cycle gas turbine power plants emit less than half the CO2 per kWh of the oldest, least efficient coal-fired plants.
That last sentence is key. Although gas-powered plants are on average 37% more efficient than coal-fired plants, the best gas plant is far, far more efficient than the worst coal plant. As Sean Casten notes, even a relatively low carbon price can begin to shift generation on the margin. Sean somewhat fancifully observes that, at least in theory, if we fully used the current capacity of our gas plants, we could shut down 93% of our coal plants without decreasing our electricity supply.
This isn’t really true on a technical level, and certainly the economics wouldn’t support a scenario like this. But the potential is big enough for Joe Romm to declare that natural gas “may be the single biggest game changer for climate action in the next two decades.”
Natural gas is, of course, a fossil fuel, and everything from the extraction to the burning of it carries environmental consequences. Nevertheless, even Greenpeace is on board with the idea of significantly boosting use of natural gas as a low-carbon stepping stone away from coal and towards a truly no-carbon future.
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