Rather than trying to pin down and capture methane emissions leaking into the atmosphere because of its potent warming potential, policy makers can ignore methane reduction efforts and instead invest in renewables to meet climate change goals more efficiently, researchers at the Massachusetts Institute of Technology posit in a research paper.
The researchers said that supercharging investments in renewables to replace coal generation will have a greater long-term carbon dioxide reduction effect because it avoids the potential of locking in natural gas use for a longer period. Policies that favor carbon-free power can help the U.S. meet 2030 carbon dioxide emissions reduction targets even though gas would still be a significant part of the energy mix.
The difficulty in cutting methane emissions is there is very little agreement on how much methane is being emitted, where it's leaking from, and how to measure any reductions, the paper said. "Fugitive emissions can be escaping all the way from where natural gas is being extracted and produced, all the way along to the end user," coauthor Jessika Trancik said in a statement with the study's Dec. 16 release. "It's difficult and expensive to monitor it along the way."
That challenge inspired Trancik and fellow MIT researcher Magdalena Klemun to look at alternatives. "An important thing to keep in mind when thinking about greenhouse gases is that the difficulty in tracking and measuring methane is itself a risk," Trancik said. "If researchers are unsure how much there is and where it is, it's hard for policymakers to formulate effective strategies to mitigate it. This study's approach is to embrace the uncertainty instead of being hamstrung by it."
Policymakers will need to choose between further investments in methane reduction — finding and plugging leaks in the gas system from the wellhead through pipelines to homes and power plants — or in renewable systems, to meet climate change goals, the authors said. Although wind and solar power is not totally carbon-free on a life-cycle basis, they accounted for that in their calculations.
To achieve a 32% reduction in carbon dioxide equivalent emissions from 2005 to 2030, the researchers' baseline scenario said methane emissions will have to be dramatically scaled back for gas to be a major component of the nation's energy mix. The scenario called for methane emissions reductions ranging from 40% to 88% depending on how much is actually leaking. The research then modeled other scenarios where renewables displace coal, gas use held steady and no leakage mitigation was required. Each was able to meet the 2030 target, but the scenario with the deepest CO2 cut has power from renewables almost doubling between 2014 levels and 2030.
"Pursuing deeper CO2 reductions instead of a [methane] clean-up effort would not only achieve the 2030 CO2-equivalent target but would also allow the U.S. to move closer to the reduction in fossil fuel use needed to reach 2050 targets," the study concluded.
They note that the Obama administration's 2016 Mid-Century Energy Strategy for decarbonizing the electricity sector envisions natural gas' share of the power stack declining to less than 10% by 2050 with roughly 75% of power demand being met by renewables, stranding investment in methane monitors and leak prevention. "Investments in improving natural gas infrastructure ... might see limited use beyond the next couple of decades, since natural gas would be phased out to meet more stringent climate goals," the study said.
In reaction, the nation's largest oil and gas trade group said natural gas is driving down U.S. carbon emissions and more investment in the sector is needed as it works to reduce methane emissions.
"The low-cost fuel is the leading reason why U.S. emissions are at the lowest levels in a generation," API spokeswoman Bethany Aronhalt said. "The idea that we cannot increase energy development while driving climate solutions is obsolete and contradicts the industry's continued progress in minimizing emissions."