Researchers say cat litter could be antidote to climate change

CAMBRIDGE, Mass. — Researchers at the Massachusetts Institute of Technology say they have found a powerful new tool in the fight against global warming. It’s basically cat poop.

They soaked an odorous clay used in a cat litter box in a copper solution to create a compound they say sucks in methane from passing air and turns it into carbon dioxide, a gas. Greenhouses are much less toxic.

The Department of Energy has provided researchers with $2 million to design devices with the compound that can be attached to vents at coal mines and dairy farms. big methane generator. The idea is to change the chemistry of the exhaust gases before they are released into the open air, like a catalytic converter in a car.

The MIT researchers say their findings have the potential to significantly reduce the amount of methane in the atmosphere and slow down global warming. The discovery could also create another possible application for zeolite, a clay used to clean up some of humanity’s worst messes, from oil spills in driveways to crisis of 2011 at the Fukushima Daiichi nuclear power plant in Japan.

Zeolite’s magic lies in its microscopic pores, allowing it to act as a filter or a sponge, depending on the chemistry. It is used to strengthen cement, improve soil, eliminate odors, keep fruit from ripening, and soothe cow stomachs. Keeping methane out of the atmosphere may be its biggest job.

Red MIT professor Desirée Plata and doctoral student Rebecca Brenneis say their team’s findings have the potential to significantly reduce atmospheric methane.


Ryan Dezember / The Wall Street Journal

Known commercially as natural gas, methane is many times more effective at trapping heat in the atmosphere than carbon dioxide, a by-product of methane combustion at power plants, on the kitchen or oil well on top. Much methane enters the atmosphere in concentrations too low to ignite.

Beside coal mines and burping cattlemethane seeps from swamps, landfills, manure compaction and permafrost melts. It bubbled up from the bottom of the lake and exited the pipelines and drilling sites. Termites are notorious emitters.

The natural ability to process methane has been overwhelmed by human activity, from hot baths to burgers. National Oceanic and Atmospheric Administration scientists recorded the largest annual increase in atmospheric methane last year, with average concentrations about 162% larger than pre-industrial levels. .


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Desirée Plata, the MIT professor who led the work, said that if emissions from coal mines around the world were filtered through copper zeolites, methane could stop accumulating in the atmosphere. According to climate experts, if methane emissions are reduced by 45% by 2030, warming is expected to be cut by half a degree Celsius by 2100.

Half a degree is nothing to sniff. The United Nations think tank on climate change says the difference between a 1.5 degree Celsius increase in average global temperatures above pre-industrial levels and 2 degrees Celsius (0.9 degrees Fahrenheit difference) equivalent to ecological turmoil. The rate of species loss for plants and animals is double and triple for insects. Crop yield decreased by 7% instead of 3%. Almost no Coral reefs surviving wave.

Rebecca Brenneis, an MIT doctoral student, is testing a zeolite compound.


Ryan Dezember / The Wall Street Journal

The emission reduction plans are disappointed targets set by the 2015 Paris Agreement on climate change, adding urgency to developing technologies that can help slow warming. The World Meteorological Organization said last week it was likely that average global temperatures would temporarily exceed 1.5 degrees above pre-industrial levels within the next five years.

In an MIT lab crowded with gas cylinders and scientific instruments, blue soup jars, clouded around a motorized nozzle, exchange ions. Nearby, PhD student Rebecca Brenneis poured the mixture — water, copper nitrate, and a few grams of zeolite — through a fiberglass filter. Solids crack as they dry, like a desert after a rain.

Zeolite contains tiny pores, which help it act as a filter or a sponge.


F. Martin Ramin / The Wall Street Journal

Dr Plata said she was initially considering a methane-clearing compound that could be used to patch leaky pipe, which is often overlooked due to cost. Her inspiration is supertrophs, bacteria that metabolize methane that rises from the seabed and lakebed.

Her team found a way to mimic nature and break down methane without the dangerously high temperatures, explosive gases or expensive metal catalysts needed in other techniques, she said. Scientific literature recommends zeolites. So is an MIT adage: “If you want to make something cheap, make it dirty.”

According to the United States Geological Survey, zeolite typically costs between $50 and $300 a ton.

“It has crazy unique properties that are potentially incredibly valuable,” said Rob Crangle, a zeolite expert with the Geological Survey. Currently, transportation costs can be higher than raw materials, which helps explain why zeolites have lost market share in cat feces to other minerals, corn flakes, walnut shells, and old newspapers.

Last year, 87,000 tons of zeolites were extracted from nine mines in the country, the Geological Survey estimated. That is in line with recent years, but a six-fold increase from production levels before the 1990s, when more zeolites were added to animal feed and new applications emerged in water purification and control. odor.

Zeolite, a clay used in cat poop, is soaked in a copper solution at MIT’s lab.


Ryan Dezember / The Wall Street Journal

Justin Mitchell said he hears from a lot of researchers as a sales manager for KMI Zeolite Inc., which operates a mine near Death Valley, California. The Department of Energy buys a lot from the mine to soak the liquid in a barrel of radioactive waste in an underground nuclear dump in New Mexico. Mr. Mitchell will attend a biogas conference in Las Vegas later this month to introduce zeolites into processes that clean up and redirect methane fumes from composting and wastewater treatment plants into the gas grid.

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 depletion through an abundant catalyst in the ground” describes how, with more unnecessary heat to cook a pizza, zeolite has spikes copper can prevent methane from escaping.

This summer, the researchers will travel to South Dakota, where a dairy farmer has volunteered to take his family’s cattle for field trials. One big question they want to answer is how the compound will handle the moisture in the air that rises from hundreds of species of ruminants, which is difficult to replicate in the lab.

The work is still in the test tube stage at MIT. The experiments were conducted with a bunch of electronics on a countertop, tubes, a valve block and a microwave-sized reactor. A larger reactor is being installed in the mechanical engineering lab on campus for the experiments needed to determine the best size and particle configuration of the zeolite particles inside the device.

“If you can imagine all the problems when you try to blow a lot of air through cat poop, that is where we are,” says Dr. Plata.

MIT researchers are designing devices with compounds that could help clean up emissions from coal mines and dairy farms.


Ryan Dezember / The Wall Street Journal

Write to Ryan Dezember at [email protected]

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