Getting rid of coal and using more natural gas has been a touch stone for Colorado utilities – but a study from the National Center for Atmospheric Research, in Boulder, raises the prospect that the flight to gas could raise the temperature.
Xcel Energy, the state’s largest utility, is spending about $1 billion to close four coal-fired units, switch a fifth to natural gas and build a new gas-fired power plant. Tri-State Generation and Transmission Association, Colorado’s second biggest electricity provider, announced this month it is buying a 272 megawatt gas-fired power plant in Fort Lupton for an undisclosed sum, and Black Hills Energy retired four coal-power units and replaced them with two gas-fired plants at a cost of $40 million.
A big spur for the move has been efforts to meet Clean Air Act standards for ozone and regional haze – as the gas-fired plants emit less of the pollutants NOx and SO2 into the air.
The problem according to the study by Tom Wrigley, a senior NCAR researcher, is that natural gas or methane is 25 times more potent a greenhouse gas as the main greenhouse gas emission from a coal plant – carbon dioxide. Coal plants also emit sulfates which contribute to acid rain, but help cool the atmosphere.
Wrigley’s computer simulations indicate that a worldwide, partial shift from coal to natural gas would slightly accelerate climate change through at least 2050, even if no methane leaked from natural gas operations, and through as late as 2140 if there were substantial leaks.
“Relying more on natural gas would reduce emissions of carbon dioxide, but it would do little to help solve the climate problem,” says Wrigley.
“The paper is not meant to be anti-gas — just to tell people that simplistic arguments like “less CO2 per unit of energy” are only part of the picture,” Wrigley said an an email.
The only “hope to save the planet,” Wrigley said, is the deployment of 4th generation nuclear power.