Cat litter could be an antidote to climate change, researchers say

CAMBRIDGE, Mass.—Researchers at the Massachusetts Institute of Technology say they’ve found a powerful new tool in the fight against global warming. It is basically kitty litter.

They soaked a scented clay used in cat boxes in a copper solution to create a compound they believe extracts methane from passing air and turns it into carbon dioxide, a greenhouse gas much less harmful.

The Department of Energy has given researchers $2 million to design devices with the compound that can be attached to vents in coal mines and dairy barns, which are big emitters of methane. The idea is to change the chemistry of emissions before they reach the open air, like a catalytic converter on a car.

The MIT researchers say their findings have the potential to dramatically reduce the amount of methane in the atmosphere and slow warming temperatures on the planet. The discovery could also create another possible application for zeolite, a clay used to clean up some of humanity’s most nasty messes, from oil spills in walkways to the 2011 meltdown at Japan’s Fukushima Daiichi nuclear power plant. .

The magic of zeolite is in its tiny pores, which allow it to function as a filter or a sponge, depending on the chemistry. It is used to strengthen cement, improve soil, remove odors, prevent fruit from ripening, and soothe stomachs of cows. Keeping methane out of the atmosphere might be its biggest task yet.

MIT professor Desirée Plata, in red, and PhD student Rebecca Brenneis say their team’s findings have the potential to dramatically reduce the amount of methane in the atmosphere.


Ryan December/The Wall Street Journal

Known commercially as natural gas, methane is much more effective at trapping heat in the atmosphere than carbon dioxide, which is the by-product of methane combustion in power plants, on stoves or at home. top of the oil wells. A large amount of methane escapes into the atmosphere in concentrations too low to be burned.

Besides coal mines and belching livestock, methane flows from swamps, landfills, manure lagoons and melting permafrost. It springs from the bottom of lakes and escapes from pipelines and drilling sites. Termites are notorious emitters.

Nature’s ability to process methane has been surpassed by human activity, from hot showers to hamburgers. National Oceanic and Atmospheric Administration scientists recorded the largest annual increase in atmospheric methane on record last year, at an average concentration about 162% above pre-industrial levels.


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Desirée Plata, an MIT professor leading the work, said if emissions from the world’s coal mines were filtered through copper zeolite, methane could stop building up in the atmosphere. If methane emissions were cut by 45% by 2030, projected warming would be reduced by half a degree Celsius by 2100, climate experts say.

Half a degree is nothing to sniff at. The United Nations climate change advisory body says the difference between average global temperatures rising 1.5 degrees Celsius above pre-industrial levels and 2 degrees Celsius (a difference of 0.9 degrees Fahrenheit) amounts to a ecological chaos. Species loss twice as fast for plants and animals, triple for insects. Crop yields fell by 7% instead of 3%. Virtually no coral reef survives.

Cat litter could be an antidote to climate change, researchers say

Rebecca Brenneis, a PhD student at MIT, tests a zeolite compound.


Ryan December/The Wall Street Journal

Plans to cut emissions fall short of targets set by the 2015 Paris Climate Change Agreement, adding to the urgency of developing technologies that can help slow warming. The World Meteorological Organization said last week that the odds are even that global average temperatures will temporarily rise 1.5 degrees above pre-industrial levels over the next five years.

In an MIT lab filled with gas cylinders and scientific instruments, jars of cloudy-sky-blue soup lapped around a mechanized spindle, exchanging ions. Nearby, PhD student Rebecca Brenneis poured the mixture – water, copper nitrates and a few grams of zeolite – onto a fiberglass filter. The solids crackled as they dried, like a desert after rain.

Cat litter could be an antidote to climate change, researchers say

Zeolite contains tiny pores that allow it to function as a filter or sponge.


F. Martin Ramin/The Wall Street Journal

Dr Plata said she was originally thinking about a methane erasing compound that could be used to repair leaky pipelines, which are often overlooked due to expense. His inspiration was methanotrophs, bacteria that metabolize bubbly methane from seabeds and lake beds.

Her team looked for ways to mimic nature and break down methane without dangerously high temperatures, explosive gases or expensive metal catalysts required in other techniques, she said. Scientific literature has suggested zeolite. So does an adage from MIT: “If you want to make something very cheap, make it with dirt.”

Zeolite typically costs between $50 and $300 a ton, according to the US Geological Survey, which deemed the mineral plentiful enough not to bother estimating reserves.

“It has crazy unique properties, which are potentially incredibly valuable,” said Rob Crangle, acting zeolite specialist at the Geological Survey. For now, shipping can cost more than the material, which is why zeolite has lost market share in kitty litter to other minerals, shredded corn stalks, walnut shells and old newspapers.

Last year, 87,000 metric tons of zeolite were mined from nine national mines, the Geological Survey estimates. This is consistent with recent years, but has increased approximately sixfold from production levels before the 1990s, when more zeolite was added to animal feed and new applications emerged in water filtration. water and odor control.

Cat litter could be an antidote to climate change, researchers say

Zeolite, a clay used in cat litter, bathed in a copper solution in an MIT lab.


Ryan December/The Wall Street Journal

Justin Mitchell said he hears a lot of seekers as a sales manager at KMI Zeolite Inc., which operates a mine near Death Valley, California. The Department of Energy buys lots from the mine to absorb the liquids into radioactive waste drums at an underground nuclear power plant. dump in New Mexico. Mr Mitchell will travel to a biogas conference in Las Vegas later this month to launch zeolite in processes that purify and divert methane vapors from manure lagoons and sewage treatment plants to the grid gas.

The MIT findings were peer-reviewed and published in December by the American Chemical Society’s journal ACS Environmental Au. “Atmospheric- and Low-Level Methane Abatement via an Earth-Abundant Catalyst” describes how, with little extra heat needed to cook pizza, copper-tipped zeolite can remove methane from passing air.

Researchers are heading to South Dakota this summer, where a dairy farmer has offered the family herd for field testing. A big question they want to answer is how the compound will handle the moisture in the air that comes from hundreds of ruminants, which is difficult to replicate in a lab.

Work is still in the test-tube stage at MIT. Experiments are carried out with a tangle of electronics table, tubes, a block of valves and a reactor the size of a microwave. A larger reactor is being installed in a mechanical engineering lab on campus for the experiments needed to determine the best grain size and configuration of the zeolite particles inside the device.

“If you can imagine all the trouble when trying to blow a lot of air through kitty litter, that’s where we are now,” Dr. Plata said.

Cat litter could be an antidote to climate change, researchers say

MIT researchers are designing devices with the compound that could help clean up emissions from coal mines and dairy barns.


Ryan December/The Wall Street Journal

Write to Ryan Dezember at [email protected]

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