The gas industry is fond of saying that burning gas for energy will help tackle climate change. Australian energy company AGL says burning coal seam gas (CSG) results in 50% less greenhouse gas emissions than coal. Industry advertising campaigns bump up that figure to 70%.
But a new peer-reviewed study has found that replacing coal-fired power stations with gas won’t help stop climate change at all. The study said a worldwide move from coal to gas would not cut greenhouse gases in the next 100 years, and maybe not for 250 years.
The study, by Nathan Myhrvold from technology company Intellectual Ventures and Stanford climate scientist Ken Caldeira, was published on February 16 in the US Institute of Physics’ Environment Research Letters.
The authors carried out a “life cycle analysis” of the emissions from various technologies and compared them with coal. For natural gas, the study accounted for the emissions created by building new gas-fired power plants and the methane — a greenhouse gas with a warming impact about 100 times worse than carbon dioxide over 20 years — that leaks from drilling and transporting gas.
The study also took into account the long time that greenhouse gases stay in the atmosphere and the very slow pace that the world’s oceans will cool down. Greenhouse gases emitted today will still be warming the planet decades from now.
Myhrvold and Caldeira’s results wipe out the gas industry’s claim that gas is a “transition fuel” that can buy us time to avoid runaway climate change. Even if all coal-fired power plants in the world were replaced with gas over the next 40 years it would hardly make a difference.
They said: “Natural gas plants emit about half the greenhouse gases emitted by coal plants of the same capacity, yet a transition to natural gas would require a century or longer to attain even a 25% reduction in [high greenhouse gas emission] warming.
“Natural gas substitution thus may not be as beneficial in the near or medium term as extrapolation from ‘raw’ annual greenhouse gas emissions might suggest.”
The report concluded that burning gas for energy “cannot yield substantial temperature reductions this century”.
Myhrvold told Climatecentral.org’s Mike Lemonick on February 28: “The most surprising thing we found is that unless you switch to a form of energy that cuts emissions really drastically, you basically don’t get any real effect …
“If you take 40 years to switch over entirely to natural gas, you won’t see any substantial decrease in global temperatures for up to 250 years. There’s almost no climate value in doing it.”
Myhrvold told Climatecentral.org that several people had challenged some of the study’s assumptions about the life cycle emissions from gas. But he insisted that it did not affect the study’s key conclusions.
He said: “The main idea is that if you’re transitioning to something that’s only twice as good as coal, it’s not really worth your time. If you’re doing something that’s better by a factor of 10, it’s reasonable.”
Myhrvold also told Climateprogress.org’s Joseph Romm that the study did not model the climate impact of “unconventional” gas sources, such as shale and coal seam gas.
He said estimates of the emissions caused by unconventional gas are “still controversial” because relatively few studies have been made. But he said “people are coming in with higher emissions from shale than conventional gas. That would tend to make any shale gas scenarios worse than the natural gas scenarios we cover”.
Myhrvold and Caldeira’s findings are similar to other recent studies of the climate impact of gas.
In September last year, the US National Center for Atmospheric Research’s Tom Wrigley published a peer-reviewed study that said: “In summary, our results show that the substitution of gas for coal as an energy source results in increased rather than decreased global warming for many decades — out to the mid 22nd century [if gas leakage rates reach 10%.]”
Myhrvold and Caldeira’s report warned that even if zero carbon energy is built to replace coal “there is no quick fix”. Even a fast rollout of wind and solar power may not lead to any cut in greenhouse gases until after 2050.
However, they said: “Despite the lengthy time lags involved, delaying rollouts of low-carbon-emission energy technologies risks even greater environmental harm in the second half of this century and beyond. This underscores the urgency in developing realistic plans for the rapid deployment of the lowest greenhouse gas emission electricity generation technologies.”
Myhrvold and Caldeira do say that nuclear power should be part of this future zero carbon energy mix, alongside wind and solar energy.
Nuclear power has low greenhouse gas emissions, but it is still a highly dangerous technology that causes other big environmental and social problems. Last year’s Fukushima disaster and the Chernobyl meltdown before are painful reminders of this.
In any case, the climate benefits of nuclear power are far from conclusive. A 2008 study by the University of Singapore’s Benjamin K Sovacool said nuclear emits two times more greenhouse gases than solar panels and six times more than onshore wind farms.
Sovacool said: “So for every dollar you spend on nuclear, you could have saved five or six times as much carbon with [energy] efficiency, or wind farms.”
