Lowering warming within our lifetimes

A flexible membrane that captures methane gas bubbles escaping from rivers, lakes, wetlands and oceans offers a route to sequestering this potent greenhouse gas and lowering the rate of climate warming within decades, according to Mechanical Engineering Professor Kripa Varanasi and Civil & Environmental Engineering Professor Desirée Plata.

Concentrated methane gas percolates up through sediments and geologic seeps into the water column, creating the world’s largest source of methane emission. Varanasi and Plata envision deploying the membrane to both capture and recover the gas—potentially for use as an economically vital fuel stock. If gasphilic membranes placed near underwater methane sources could reduce emissions by only 190 million metric tons per year—a lofty but achievable goal—this technology could save 0.5 degrees C of warming by 2100.

“It seems impossible for a single technology to bend the curve of accumulating methane in the atmosphere, but that is exactly the bold vision what we seek to realize,” say Varanasi and Plata.

In labs, seas and lakes

Discussions between the two scientists inspired them to join forces on this project. The membranes developed in the Varanasi Lab can be engineered into a variety of shapes, including flat films and rolled cylindrical tubes. The Plata Group has expertise in methane quantification, recovery and destruction.

“The traditional failure modes—of the engineer who doesn’t understand the environment, or the environmental scientist who doesn’t get material or energy constraints—will not occur here,” the scientists suggest.

Varanasi and Plata will design and deploy these membranes at laboratory scale in a test tank, a local lake and in the ocean at the Santa Barbara oil seeps to study and optimize the capture and transport of methane bubbles across the membrane. They will also explore ways to modify the membrane surface and develop integrated systems to promote gas transport and facilitate gas transfer into a collection vessel without disturbance to critical ecosystem functions.

Even though methane emissions will be responsible for nearly half of the world’s warming over the next 20 years, less than 5% of all climate financing goes to methane and other non-carbon dioxide greenhouse gas technologies. “There are functionally zero agencies—federal, private or philanthropic—that attempt to solve this challenge,” Varanasi and Plata note.

“The Bose funds will enable a first-of-its-kind demonstration of our technology and give the world hope that these otherwise unstoppable methane leaks can be turned off and even utilized as a fuel source,” they add.

Why methane?

Methane is an abundant and potent climate pollutant. Its accumulation in the atmosphere is skyrocketing, exacerbated by warming that leads to more of the gas being produced and released. However, it is also short-lived, lasting only 12 years in the atmosphere compared to about 1000 years for carbon dioxide.

Instead of waiting until methane reaches the atmosphere, Varanasi and Plata want to seize some of it at its watery sediment source and limit its role in pushing the planet further toward rapid climate change. “We see this innovation as able to help avoid those climate tipping points, create value, and respond—the way MIT engineers do—to the emergency of accelerating greenhouse gas (GHG) emissions,” they say.