The AirJoule system consists of two chambers, each with surfaces coated with this special material. They take turns dehumidifying a stream of air. One chamber is always drying the air passing through the system while the other gradually releases moisture it had previously accumulated. Some heat from the drying chamber is applied to the moisture-saturated lining of the other, as that helps water drip away. These two cavities switch duties every 10 minutes or so, Jore says.
This process does not cool the air, but it does allow dry air to be introduced into a more traditional air conditioning unit, dramatically reducing the amount of energy that secondary unit will use. Jore claims that AirJoule consumes less than 100 watt-hours per liter of water vapor removed, potentially reducing the energy needed for dehumidification by up to 90 percent compared to a traditional dehumidifier.
Montana Technologies wants to sell the components of its AirJoule system to established HVAC companies rather than trying to make its own consumer products and compete directly with those companies; the approach is called AirJoule Inside. The company is also working on a system for the U.S. military, based on the same technology, that can harvest drinking water from the air. Useful for troops stationed in the desert, one imagines. AirJoule is still in the prototype and testing stages, though.
“We are building several of these pre-production pilot units for potential customers and partners,” says Jore. “Think rooftops of major retail chains.”
Rival company Blue Frontier has also introduced a desiccant-based dehumidifier system, although it uses a liquid desiccant — a salt solution that is capable of collecting moisture from the air. CEO Daniel Betts says his company is installing the technology in several undisclosed locations across the United States, including office spaces, warehouses and restaurants. Three of them are up and running, with six more to be installed before the end of the year.
As with AirJoule, Blue Frontier’s approach would tie into a separate secondary air conditioning process to cool dry air. And Blue Frontier must also account for the need to regenerate its desiccant, although this process can be separated from dehumidification and run at times when there is less demand on the grid. “We’re shifting the air conditioning load from peak hours,” Betts says.
Large air conditioning systems work differently than the unit you may have in your home or apartment. Take centralized cooling plants in hotels as an example. They circulate cold liquid to guest rooms, where it is used to cool the air. Cooling plants that reduce the temperature of this liquid are already reasonably efficientBut they still have to draw power from the grid during peak times, such as in the late afternoon when everyone wants to cool off from the heat of the day, says Yaron Ben Nun, founder and chief technology officer of Nostromo Energy, which focuses on energy storage.
To solve this problem, Nostromo has created a system called IceBrick, which it installed last year at two adjacent hotels in California: the Beverly Hilton and the Waldorf Astoria Beverly Hills. The IceBrick, a rectangular module, sits on the roof of a building. It contains nearly 200 insulated capsules of water that can be frozen when power is available during off-peak hours. Then, in the middle of a hot day when hotel guests are starting to swelter, the cooling plant can use that stored cold, so to speak, to avoid paying high electricity prices. This doesn’t mean a reduction in energy consumption—in fact, it increases it slightly—but Ben Nun says the system can reduce annual cooling costs by 30 percent and associated emissions by as much as 80 percent, because the IceBrick can wait to consume power at times when there’s plenty of renewable electricity available on the grid (for example, when wind turbines are spinning at full blast in the middle of the night).