An anonymous reader quotes a report from Wired, written by Chris Baraniuk: The buses struggling in China's muggy weather gave [Matt Jore, CEO of Montana Technologies] and his colleagues an idea. If they could make dehumidification more efficient somehow, then they could make air conditioning as a whole much more efficient, too. They headed back to the US wondering how to make this happen. [...] "I have here 50-gallon barrels of this stuff. It comes in a special powder," says Jore, referring to the moisture-loving material that coats components inside his firm's novel dehumidifier system, AirJoule. This is the result of years of research and development that followed his team's trip to China. The coating is a type of highly porous material called a metal-organic framework, and the pores are sized so that they fit around water molecules extremely well. It makes for a powerful desiccant, or drying device. "Just one kilogram can take up half or more than half -- in our case 55 percent -- of its own weight in water vapor," says Jore.

The AirJoule system consists of two chambers, each one containing surfaces coated with this special material. They take turns at dehumidifying a flow of air. One chamber is always drying air that is pushed through the system while the other gradually releases the moisture it previously collected. A little heat from the drying chamber gets applied to the moisture-saturated coating in the other, since that helps to encourage the water to drip away for removal. These two cavities swap roles every 10 minutes or so, says Jore. This process doesn't cool the air, but it does make it possible to feed dry air to a more traditional air conditioning device, drastically cutting how much energy that secondary device will use. And Jore claims that AirJoule consumes less than 100 watt-hours per liter of water vapor removed -- potentially cutting the energy required for dehumidification by as much as 90 percent compared to a traditional dehumidifier.

Montana Technologies wants to sell the components for its AirJoule system to established HVAC firms rather than attempt to build its own consumer products and compete with those firms directly -- it calls the approach AirJoule Inside. The firm is also working on a system for the US military, based on the same technology, that can harvest drinkable water from the air. Handy for troops stationed in the desert, one imagines. However, AirJoule is still at the prototype and testing stages. "We're building several of these pilot preproduction units for potential customers and partners," says Jore. "Think rooftops on big-box retailers." Montana Technologies isn't the only firm using cutting-edge technology to make air conditioning units more efficient. Rival firm Blue Frontier has developed a desiccant-based dehumidifying system using a liquid salt solution, with installations in various U.S. locations, that links to a secondary air-conditioning process and regenerates desiccant during off-peak hours to reduce peak electricity demand.

Then there's Nostromo Energy's IceBrick system, installed in California hotels, which freezes water capsules during off-peak hours and uses the stored coolth during peak times. This system can reduce cooling costs by up to 30 percent and emissions by up to 80 percent, according to Wired.