Air Conditioners Might Be a Water Source of the future

Some places, like Austin, Texas — where water will probably become scarcer — have already taken steps to promote condensate reuse.

“We’re in a part of the country where we expect climate change to impact the frequency and severity of our droughts,” says Mark Jordan, an environmental program manager with Austin Water. “We want to stretch our supply as much as possible by turning more and more to reuse. We’re really promoting that as a way to meet water demands for the next hundred years.”

Two prominent Austin structures use the technology. First, the Austonian, a 56-story residential skyscraper, captures some 12,800 gallons of condensate a year, using this to irrigate a 10th-floor green space. Second, Austin Central Library combines alternative water sources including reused condensate, rainwater harvesting, and reclaimed water to save some 350,000 gallons per year — enough to meet nearly 90% of the library’s water demands.

In an attempt to get other large indoor spaces to follow suit, the Austin City Council in April approved an incentive program aimed at fostering the use of reclaimed water, including condensate. Commercial developments that use reclaimed water to replace between 1 million and 3 million gallons of potable water per year can obtain $250,000 in city funding; those that save more than 3 million can get $500,000. Similar programs already exist in San Francisco and San Antonio.

Still, there are a few obstacles to wider adoption. Building condensate reuse systems has an upfront capital cost, and some places produce more condensate than others. Condensation forms best when hot, humid air contacts a cold surface. Think of a mirror and a hot shower. For this reason, the deep American South and other hot, humid places have the potential to produce far more condensate. Many of these places, too, already have enough water (for now).

Broadly, the American West — which is already seeing megadroughts and water shortages, especially in regions like the Colorado River Basin — has a hot, dry environment less conducive to creating air conditioner condensate. But the sharply escalating water emergency has spurred some groups to leave nothing to waste.

For one, the University of Arizona’s College of Architecture, Planning & Landscape Architecture building reuses some 95,000 gallons of condensate a year, routing it to a pond and garden. One of its professors, Jonathan Bean, says reusing condensate is important but not a critical piece in counteracting climate change. He believes there are more effective strategies, such as making buildings smaller and reconsidering refrigerants.

Nevertheless, reusing condensate, Bean believes, makes for more climate-intelligent buildings — even in hot Arizona, which only gets real humidity during a summer monsoon season. “It makes sense,” to divert the water to a garden, he said. “It’s a resource that you’re expending a fair amount of energy to generate, so why wouldn’t you?”

While the water volume from air conditioners humming in big buildings is small compared with rivers and the underground aquifers, it can make a difference, especially when combined with other alternative water sources like rainwater capture and treated wastewater. Even this smaller volume can green gardens, fill toilets, provide cooling, meet partial needs of single buildings, shorten water supply chains (saving energy), and make people more conscious of water’s scarcity.

In 2019, the San Diego International Airport embarked on one project to draw more attention to water conservation: turning condensate into beer. Before the pandemic, it partnered with Ballast Point Brewing to turn some of the condensate from its massive cooling towers used to control airport temperature. The result was SAN Test Pilot, a lighter German-style kölsch beer that needs good water. Three Ballast Point locations in San Diego poured the beer while the batch lasted.

Image: San Diego County Regional Airport Authority

It’s just one way the airport has experimented with water reuse. In an average year, the airport collects some 100,000 gallons of condensate, mostly for cooling towers and power washing. According to Richard Gilb, manager of the airport’s planning and environmental affairs department, the airport has been reusing condensate since 2014.

“Since we’re in a coastal environment, there’s enough humidity to create condensate on a regular basis,” he said. “It was just dripping on the ground and it looked like a pretty good source of water we should do something with.”

Though the pandemic temporarily dashed hopes for further batches, Gilb hopes to partner with other San Diego breweries to make more beer from condensate in the future. He even dreams of serving pints in terminals — making people conscious of what can be done, sharing a frosty-cold testament to possibilities already here.

See more here: bloomberg.com

PSI editor’s note: Principia Scientific International does not believe there is any climate change, other than that which occurs naturally

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