Household cooling without heating the planet: new technology for more efficient air conditioning

Startup Transaera is using a class of materials called organic metal frames, or MOFs, to create air conditioners that could have five times less impact on climate compared to traditional ACs.

The Transaera startup is using a class of materials, advanced by MIT Professor Mircea Dinca for more than a decade, to create a more energy efficient air conditioner.

As incomes in developing countries continue to rise, demand for air conditioners is expected to triple by 2050. The increase will multiply what is already a major source of greenhouse gas emissions: air conditioning is currently responsible for nearly 20 percent of electricity use in surrounding buildings. the world.

Now startup Transaera is working to curb those energy demands with a more efficient air conditioner that uses safer refrigerants to cool homes. The company believes its machine could have a fifth of the impact on the climate compared to traditional ACs.

“The thing about air conditioning is that the basic technology hasn’t changed much since it was invented 100 years ago,” says Transaera chief engineer Ross Bonner SM ’20.

That will change quickly if the small Transaera team succeeds. The company is currently a finalist in a global competition to redesign air conditioning. The winner of the contest, called the Global Cooling Prize, will obtain 1 million dollars to commercialize their machines.

At the heart of Transaera’s design is a class of highly porous materials called organometallic scaffolds, or MOF, which passively extract moisture from the air while the machine is running. Co-founder Mircea Dincă, a WM Keck professor of energy in MIT’s Department of Chemistry, has conducted pioneering research on MOF, and the company’s team members see the commercial advancement of materials as an important part of their mission.

“MOFs have many potential applications, but what holds them back is unit economics and the inability to cost-effectively manufacture them at scale,” says Bonner. “What Transaera intends to do is be the first to commercialize MOFs at scale and lead the way in bringing MOFs into the public domain.”

Dincă’s co-founders are Transaera CEO Sorin Grama SM ’07, who is also a professor at MIT D-Lab, and CTO Matt Dorson, a mechanical engineer who worked with Grama at a previous startup.

“This idea of ​​creating something revolutionary motivates me,” says Grama. “We have designed these new devices, but we are also bringing this material knowledge, with Mircea and our collaborators, and combining the two to create something really new and different.”

A material of opportunity

Grama and Dorson previously collaborated at Promethean Power Systems, which develops off-grid cooling solutions for farmers in India. To date, the company has installed 1,800 refrigeration systems serving approximately 60,000 farmers each day. After leaving the CEO role in 2015, Grama returned to the Institute to teach at MIT D-Lab and work as an Entrepreneur-In-Residence at the Martin Trust Center for MIT Entrepreneurship.

During that time, Grama learned about MOFs from Rob Stoner, deputy director of science and technology for the MIT Energy Initiative and founding director of the MIT Tata Center.

Stoner introduced Grama to Dincă, who had been studying MOF since joining the MIT faculty in 2010 and grew up 10 miles from Grama’s hometown in Romania.

MOF’s intriguing properties come from its large internal surface area and the ability to fine-tune the size of the tiny chambers running through it. Dincă previously developed MOFs with chambers large enough to trap water molecules from the air. He described them as “sponges on steroids.”

Grama began to think about using the material for cooling, but soon another application was presented. Most people think that air conditioners only cool the air in a space, but they also dry out the air that they are cooling. Traditional machines use something called an evaporator, a cold coil to draw water out of the air through condensation. The cold coil must be much colder than the desired temperature in the room to collect moisture. Dorson says that removing moisture from the air consumes about half the electricity traditional air conditioners use.

Transaera MOFs collect moisture passively when air enters the system. The waste heat from the machine is used to dry the MOF material for continuous reuse.

Transaera was formally founded in early 2018 and the Global Refrigeration Award was announced later that year. Hundreds of teams expressed interest, and Transaera was ultimately selected as one of eight finalists and received $ 200,000 to deliver prototypes to competition organizers.

Bonner joined the company in 2019 after exploring pathways to carbon-neutral AC as part of a mechanical engineering class at MIT.

When Covid-19 started sweeping countries around the world, it was decided that the Cooling Prize tests in India would be conducted remotely. In addition to the challenge, the co-founders did not have access to their lab in Somerville due to restrictions and were using their own tools and garages to complete the prototypes. After submitting their prototypes, Transaera had to help Prize organizers install them via live video feed for field testing at multiple locations in India. The team says the results validated Transaera’s approach and showed that the system had significantly less climate impact than the reference units.

The Transaera system also used a refrigerant known as R-32 with zero ozone depletion potential (ODP) and a global warming potential approximately three times lower than another commonly used refrigerant.

The milestone further convinced the small Transaera team that they were onto something.

“This air conditioning problem can have a real material impact on people’s quality of life,” says Dorson.

Driving a field forward

The Global Cooling Prize will announce its winner next month. Regardless of what happens, Transaera will grow the team this year and conduct additional tests in Boston. The company has been working with large manufacturers who have supplied equipment for prototypes and shown the founders how they could integrate their devices with existing technologies.

The company’s fundamental work with MOFs has continued even as Transaera’s air conditioning approaches commercialization. In fact, Transaera recently received a grant from the National Science Foundation to explore more efficient pathways to MOF production with a laboratory at MIT.

“MOFs open up so many possibilities for all kinds of revolutionary devices, not just in air conditioning, but also in water harvesting, energy storage, and supercapacitors,” says Grama. “This knowledge that we are developing can be applied to many other applications in the future, and I feel that we are pioneers in this field and we are advancing to the forefront of technology.”

Still, Transaera’s founders remain focused on getting their air conditioner to market first, recognizing that the problem they’re trying to tackle is big enough to keep them busy for a while.

“It’s clear when you look at the swath of the world that is in the hot and humid tropics, there is a growing middle class and one of the first things they will want to buy is an air conditioner,” says Dorson. “Developing more efficient air conditioning systems is essential for the health of people and the environment of our planet.”

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