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Turn methane into CO2 to reduce heating, experts suggest



Most plans to tackle climate change are about reducing carbon dioxide, usually by reducing human emissions.

But an unconventional new idea could actually slow down the development of global warming by putting more carbon dioxide into the atmosphere – while removing a more potent planet-heating gas in the process.

In a comment published Monday in the journal Nature Sustainability a group of climate and chemistry experts said that methane should focus more on the fight against climate change. Methane continues for much shorter time in the atmosphere than carbon dioxide, but is a much more powerful climate-warming gas while it lasts.

Capturing atmospheric methane and converting to less potent carbon dioxide using special materials and chemical catalysts can be a way to reduce the warming potential of greenhouse gases in the air, the authors say.

The idea is not intended to be a substitute for reducing emissions, noted commentator author Rob Jackson, a climate and environmental researcher at Stanford University.

"The smartest thing to do is keep methane and carbon dioxide from entering the atmosphere," he said. "It's just that emissions are still rising and we need to think of other tools and methods to combat climate change."

Returning greenhouse gases out of the atmosphere, in addition to reducing emissions entering it, is a long-discussed idea among climate scientists and activists. But it has mostly focused on carbon dioxide until this point.

The idea has typically focused on ways to suck CO 2 out of the air and then store it away so that it does not leak back into the atmosphere ̵

1; a process widely known as "negative emissions" . The net result would be a lower total concentration of carbon dioxide in the atmosphere.

Scientists have suggested a variety of ways to extract it, from large forests filled with carbon-confusing trees that naturally absorb carbon dioxide, to special machines that would suck CO 2 out of the air. In the latter scenario, the captured carbon dioxide should then be permanently stored away somewhere, probably by injecting it deep into the soil.

There has been much less focus on capturing methane, probably partly because the process is more technically difficult than capturing carbon dioxide. But scientists have some ideas on how to do it.

The new comment suggests a promising method involving the use of porous minerals called zeolites. Scientists are already using zeolites to capture methane and convert it to methanol, an alcohol that can be used in chemical raw materials or other industrial applications.

It is not much more chemically complicated to convert methane to carbon dioxide instead, to Jackson. Once the conversion has taken place, the most cost-effective action would be to simply release carbon dioxide back into the atmosphere. This means that more CO 2 2 ends up in the air, but because it accommodates a more potent greenhouse gas, the immediate effect is to reduce the progress of global warming.

Currently, the concentration of methane in the Earth's atmosphere is hovering around 1,866 parts per million. billion. Prior to the industrial age, when human emissions of greenhouse gases began to skyrocket, methane levels were closer to 750 ppb.

Recovery of the atmosphere to its pre-industrial methane concentrations would produce about 8 billion tons of carbon dioxide in the conversion process, Jackson and fellow note. This is equivalent to a few months' current global carbon dioxide emissions. Currently, the world emits about 40 billion tons of carbon dioxide each year.

"It's not trivial, but it's not a breaker," Jackson said.

Since the concept is almost entirely hypothetical at the moment, it is difficult to outline all the conditions that would be needed to develop it and bring it to a scale.

When it comes to direct air capture of carbon dioxide – its closest existing analogue – the cost of using the technology and the challenges of developing a market for it are some of the biggest obstacles. Experts have pointed out that federal incentives may be needed for companies to consider investing in technology. It can mean anything from a carbon emissions tax to a carbon removal subsidy.

The same will probably be true for methane conversion, the authors of the new comment say, noting that "a price of carbon emissions or a policy mandate would be necessary" for the process of becoming economically attractive. In such a scenario, however, they note that methane attacks can become even more attractive than carbon dioxide capture. The price of methane is likely to be higher because it is a more potent greenhouse gas than carbon dioxide.

All the details remain to be discussed. For now, the idea is just a concept – but it is one that some experts say could potentially add a new tool to the weapon's arsenal against climate change.

"We should look at the possibilities of removing all the major greenhouse gases," said David Victor, a climate and energy political expert at the University of California, San Diego, in an emailed comment on E&E News. "After CO 2 methane is the next leading candidate."

Reprinted from Climatewire with permission from E&E News. E & E provides daily coverage of important energy and environmental news at www.eenews.net.


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