As summers become more sweltering, homeowners are turning more and more to air conditioning to keep cool. But that cool air comes with a price. According to the Department of Energy, air conditioners use about 6 percent of all electricity produced in the United States, releasing about 117 million metric tons of carbon dioxide each year.
Colorado-based M-Cycle is out to change this trend with a more efficient cooling system — and a principle that its founders say could revolutionize power production by producing energy from just air.
The company relies on the Maisotsenko Cycle. In a conventional air conditioning system, warm outside air is pulled in and run over a cold surface to both cool it and remove its moisture, a process that takes a good deal of energy. In dry Colorado, many homes use evaporative cooling — or swamp coolers — which lowers the temperature of the outside air by blowing it over cool water. This results in a more efficient cool, but a more humid environment inside.
The Maisotsenko Cycle relies on indirect cooling, essentially treating outside air with another stream of warm air to remove the moisture from the cooler air. That results in a cool and dry product that can produce temperatures well below an evaporative cooler, but without the cost and energy use of a conventional air conditioner. The drawback is that it produces less air, requiring more fan power to move it around and cool a room, but even that generally requires less energy than what a conventional cooler needs to chill the air.
When the principle was tested in a 2009 contest run by the University of California Davis Western Cooling Efficiency Center, it showed an 80 percent reduction in energy use and 60 percent peak demand reduction. Experts say the concept is sound — by dehumidifying the air, the M-Cycle units can take the temperature below what’s called the wet bulb point, the limit for evaporative coolers, down to the lower dew point.
“Once you have this cool air, you’re just moving it with a fan, and that’s all the power you need,” said Eric Kozubal, an engineer with the Commercial Buildings Research Group at the National Renewable Energy Laboratory in Golden. But, Kozubal added, there is a limit to how effective the technology can be.
“As the outside dew point increases, you have to start pushing a lot more air. At some point, you run out of efficient temperature change,” he said. “In a hot and dry place like Colorado, Arizona or New Mexico, it makes sense, but not east of the Mississippi.”
The concept comes from Dr. Valeriy Maisotsenko and was first applied in cooling units produced by Denver-based Coolerado. That company was purchased by Australian air conditioning giant Seeley International in 2015, but the founders have reformed as M-Cycle Cooling. They are producing 1,000 solar-powered cooling units designed for recreational vehicles as a proof of concept for their new model.
But, says M-Cycle CEO Stan May, that’s just the start.
“For us, AC is the fringe of this technology,” May said in an interview. The essence of the technology, he added, is “converting air itself into energy.”
By utilizing the potential energy from the latent heat in air, M-Cycle says it can produce energy with minimal waste and little input — just the power needed to run a fan and pump to move the streams of air. The company was approved for a U.S. patent for a power generation method, and the concept is being studied at international universities including the City University of Hong Kong and Singapore University. However, little has been published in the United States and M-Cycle has struggled to get outside investment.
“Technically speaking, this could be applied to anything,” said Yaroslav Chudnovsky of the Gas Technology Institute who has studied the Maisotsenko Cycle. “I think power generation is the best application. In most power generation, waste heat is just put out … it is meaningful when you can reuse it in the same system.”
Kozubal said the principle has been used to augment the performance of a gas turbine, recycling the excess heat and reducing waste to make it run more efficiently. But, he added, it would take a good deal of air and could lose its efficiency gains.
For May, however, the Maisotsenko Cycle could end up replacing pistons in everything from power plants to cars, offering enormous efficiency gains and slashing the need for fossil fuel consumption. The cooling units are the company’s start, but May said the technology could revolutionize the energy sector.
“Imagine your father was Tesla and he leaves you a box with ideas, and every single idea is world-changing,” he said. “That’s the circumstance I feel I am in.”