The Rise In Demand For Cooling Sparks Interest In More Energy Efficient Air Conditioners

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In 2022, cooling equipment consumed an estimated 5,000 terawatt-hours (TWh) of electricity globally — about the same as the entire electricity consumption of the United States today. According to RMI, by 2050, this demand is projected to more than triple to 18,000 TWh. We could, of course, take reasonable and rational steps to keep the Earth from getting hotter, but since that seems to be an impossibility, making more energy efficient cooling systems may be the next best thing.

Transaera is one of many MIT spinoffs that focuses on using energy more efficiently to reduce the amount of carbon pollution from everyday activities, from cement, to process heat, to cooling. It has begun manufacturing the enormous rooftop air conditioning, ventilation, and heating systems we see on the roofs of big box stores and factories everywhere. The difference is that the equipment Transaera makes can cool those buildings using 40 percent less energy than traditional equipment.

The difference is that in addition to using heat pumps, Transaera employs new cutting edge MOF technology to remove moisture from the air separately from the cooling mechanism, which dramatically reduces the need for cooling. A room where the air is 80 degrees F and 10 percent humidity may be comfortable for most people, whereas the same room at the same temperature but with 90 percent humidity would be unbearably hot.

No Over-Cooling Need To Control Humidity

Conventional cooling systems ​“typically have to over-cool the air” to wring out excess moisture, which drives up energy costs, says Ankit Kalanki, who leads global initiatives to turbocharge cooling tech at clean energy think tank RMI and who has worked with Transaera in the past. The Transaera systems cost about 20 percent more than conventional systems but pay for themselves in lower energy bills in just about two years. With a typical useful life of 15 years or more, that means 13 years of energy savings for customers after the equipment is paid for. Who wouldn’t take that deal?

Using heat pump technology is part of the energy efficiency gains, but another big piece of the puzzle is the the use of metal organic frameworks, a new class of materials that won the Nobel Prize in chemistry last year for three researchers — Susumu Kitagawa of Japan, Richard Robson of Australia, and Omar M. Yaghi of the US. Yaghi is one of the three founders of Transaera.

The Nobel Prize committee said the trio “have created molecular constructions with large spaces through which gases and other chemicals can flow. These constructions — metal–organic frameworks — can be used to harvest water from desert air, capture carbon dioxide, store toxic gases, or catalyze chemical reactions.” Their ability to extract moisture from the air is what makes the Transaera system so energy efficient, because it can dehumidify with cooling the air.

Canary Media says that when looked at under a microscope, metal-organic frameworks look like clumps of melded sugar cubes. While the material can have thousands of different chemical compositions, Transaera uses a proprietary recipe ​“that is really good at soaking up water molecules.”

Sorin Grama, the company’s CEO and one of its three co-founders, says the process begins by applying a thin layer of a hydrophilic framework on a wheel with a honeycomb structure that allows air to flow through it. As the wheel spins, it removes moisture from the outdoor air before it’s cooled. This reduces energy use while delivering fresh, conditioned air to improve the health and comfort for a building’s occupants.

Removing Moisture Without Cooling

Sharp eyed readers will note that the equipment allows dehumidification without cooling. Traditionally when the air is too humid, we crank up the A/C and let the moisture in the air condense on the cold surfaces within those machines but at the cost of using more energy to operated the A/C units than necessary.

Transaera makes the dehumidification portion of the new rooftop heating and cooling equipment and partners with an unnamed US manufacturer that builds the rest of the system. The startup has previously announced $15 million in seed and grant funding.

Amazon tried a Transaera system for six months at a facility it owns in Houston. Apparently, the company was pleased with the results, because now it has signed a multi-year deal to install the units on several of its buildings. Amazon declined to say how many units it has ordered, what it’s paying, and where it would install them, but did say they would help the company hit its target of net-zero emissions by 2040.

Of course, the panic to install data centers will militate against any carbon reductions, but we should welcome any progress the company can make toward not turning the Earth into a toxic waste dump in the pursuit of profits. ProFood Properties has installed two Transaera systems at its commercial kitchen in Hialeah, Florida.

Molecular Lego

Yaghi describes MOFs as being like “molecular Lego.” He says, “You take molecular building blocks and stitch them together to form scaffolds that have enormous surface area and highly tunable chemistry.” A single gram of MOF can have an internal surface area equivalent to a football field. That’s enough space to trap vast amounts of carbon dioxide or water vapor, he says.

His passion is reticular chemistry — the science of linking molecular units into open frameworks, has given rise to what he calls the “air economy,” which he describes as harvesting valuable resources like water and carbon dioxide directly from the air around us. The concept is gaining traction, thanks in part to Atoco, a startup he co-founded recently to commercialize the ability of MOFs to provide water even in parched environments

Atoco co-founder Samar Taha describes what the company is doing as beginning of a decentralized, low energy infrastructure to deliver clean water and the means to capture carbon anywhere, even in the most remote desert or most humid city. The Atoco off-grid atmospheric water harvesters will undergo field tests in the coming months. They are powered by free ambient energy, such as solar or thermal energy.

One ton of Yaghi’s MOF material deployed in Atoco’s off-grid atmospheric water harvesters can generate up to 20,000 liters (5300 gallons) of water per day. “We’ve tested the prototypes in Death Valley,” Yaghi says. “They pull water from thin air. It’s the purest water you can get.”

Carbon Capture Too

MOFs are also able to capture carbon dioxide at low temperatures instead of relying on the high temperature chemically intensive processes used in many direct air capture plants today. This cuts operational costs and opens the door to deployment in regions and industries previously considered impractical. The materials developed by Yaghi’s group also are particularly resilient to humidity—an issue that plagues many existing carbon capture systems. “In many technologies, you have to pre-dry the air before capturing CO2. That adds complexity,” says Taha. “Ours can handle ambient air as it is.”

The cost of manufacturing MOFs is the primary factor preventing wider adoption of the technology. Selina Ambrose, product manager at Promethean Particles, a UK based company that specializes in the synthesis and production of MOFs, said, “There has been a real challenge in making MOFs in large quantities cost effectively because a lot of the manufacturing processes are reliant on batch methods, and there are real limitations in scaling that up from a chemical engineering point of view.” While that is undoubtedly true, we can expect the technology to scale quickly once more people and companies understand its benefits.

The Transaera systems come with a 20 percent price premium but offers rapid recapture of the extra cost. They look exactly like conventional large rooftop heating and cooling equipment, which is intentional. It’s products fit in the same footprint as regular equipment and uses the same electrical and plumbing connections. The only way a casual observer can tell it apart from a normal unit is the green finish and the name Transaera painted on the side.

The company plans to ramp up production to several hundred units a year as the news about its more efficient technology spreads among commercial building owners. Having Amazon endorse the equipment should give a significant boost to the company’s fortunes.