As Methane Surges, Scientists Look to Nanotech and Microbes to Capture It
Methane is many times more potent than carbon dioxide, but it's also more difficult to capture.
In efforts to fight climate change, much of the focus has been on controlling and reducing carbon dioxide emissions from burning fossil fuels. But newly published research reveals, another gas is emerging as a pressing problem.
In a study published in the journal Environmental Research Letters, scientists report that concentrations of atmospheric methane - whose greenhouse effect is 25 times more potent than CO2 - according to the U.S. Environmental Protection Agency - are rising faster than at any time in the past two decades, and that efforts are "urgently needed" to reduce it.
But that's easier said than done. While about 40 percent of methane comes from natural sources - seeping from vents in the ocean floor for example - most of it comes from an array of human-caused sources, ranging from cattle burps to venting from oil and gas wells. The exact reasons for the surge remain unclear. In their article, the scientists said analysis suggests that most of the increase is coming from agriculture, and to a lesser degree fossil fuel use, with some contribution also from natural emissions from wetlands.
Since 2004, the U.S. and more than 40 other countries have signed on to work together in the Global Methane Initiative, which aims to attack the problem though an array of measures, such as using anaerobic biodigester technology to extract methane from animal manure and trapping methane emissions from coal mines.
The captured methane - the chemical equivalent of natural gas - can be burned as a fuel that only produces about half the CO2 emissions of oil or coal. In May, the Obama Administration issued new regulations that would compel the oil and gas industry to fix leaks in tanks and pipelines to curb methane emissions, though it's unclear whether President-elect Trump, who as a candidate vowed to eliminate "unnecessary" regulations on energy production, will undo those rules.
U.S. government researchers also have been working on more exotic solutions to capture methane, which is difficult to filter out of a stream of gaseous emissions because it doesn't interact as readily as carbon dioxide does. One idea is to use molecular-level engineering to create frameworks of minerals called zeolites, which could absorb methane though nano-sized pores.
Recently, they've come up with another solution that would enable captured methane to be converted into a liquid fuel which would be easier to transport and use. Researchers extracted enzymes from methanotrophs - methane-eating bacteria - and mixed them with plastics to create a 3D-printed material that could convert gaseous methane into methanol at room temperature and pressure.
"We can use materials to make biology work better," Sarah Baker, a chemist at Lawrence Livermore National Laboratory in California, told Seeker.
Baker said the new technology, which could be on the market in as soon as five years, would make it easier to make fuel from methane emitted by sources such as landfills and municipal waste water treatment plants, and reduce the amount of methane going directly into the atmosphere.
Though methane is more efficient than trapping heat than CO2, its lifetime in the atmosphere is much shorter. That means that if methane emissions could be reduced quickly, that might buy more time to reduce its CO2 emissions.
"Methane presents the best opportunity to slow climate change quickly," Rob Jackson, chair of Stanford University's Earth science program and one of the study's authors, said in a press release. "Carbon dioxide has a longer reach, but methane strikes faster."
Image: This graphic, based on data from NASA's Aqua satellite, shows the monthly average atmospheric methane for January 2016 in various parts of the world. Credit: NASA WATCH VIDEO: What Makes Methane Gas Toxic?