Air conditioners have a climate problem.  New technology can help.

Air conditioners have a climate problem. New technology can help.

Air conditioners have a climate problem.  New technology can help.

This week, Californians were reminded of one of the most vexing paradoxes of global warming. With temperatures well above 110 degrees Fahrenheit in some regions Tuesday night, hundreds of thousands of the state’s residents received beeping text alerts to alert them that the power grid, strained under the weight of millions of air conditioning units, was about to collapse. Save power now, the text warned, or face ongoing power outages.

Consumers saved, and the state’s power grid emerged relatively unscathed from a record hot day. Still, as temperatures rise worldwide, more people will need to install air conditioners. But as currently sold, AC units can actually make global warming worse: On hot days, they suck tons of electricity from the grid, and their chemical refrigerants can accelerate global warming.

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This is why researchers and startups are hoping to create new, cutting-edge AC devices. AC technology has only seen “incremental improvements over the past 100 years,” said Ankit Kalanki, a principal at Third Derivative, a climate technology accelerator co-founded by the energy think tank RMI. “There hasn’t been a step change in innovation.”

The good news is that companies are rushing to develop more efficient ACs. The question is whether they will be ready in time.

Over the next few decades, global demand for air conditioners is expected to skyrocket. According to the International Energy Agency, the number of AC units in buildings worldwide will reach 5.6 billion by 2050, up from only around 2 billion units today.

But unless the air conditioner gets an efficiency upgrade, all these ACs will put an unprecedented strain on the power grid. Air conditioning systems and electric fans already account for approximately 10 percent of electricity consumption worldwide. On extremely hot days, AC efficiency drops, as the units have to work harder to move heat from indoors to outdoors. During a heat wave, millions of people come home and turn on their ACs at the same time, somewhere between 4:00 PM and 9:00 PM. When that happens, air conditioners can account for as much as 60 to 70 percent of electricity needs, and grills like California’s.

Meanwhile, the key component of modern air conditioning — chemicals known as refrigerants — has been the bane of the atmosphere for decades. ACs work by exposing a liquid refrigerant, a chemical with a low boiling point, to warm indoor air. That heat causes the refrigerant to evaporate into gas, cooling the air. A compressor then turns the refrigerant back into liquid and repeats the process.

The problem is that refrigerants can leak out of the air conditioner, both during use and, more commonly, when the ACs are disposed of. Early ACs were largely made with chlorofluorocarbons, or CFCs, which were responsible for one of the first truly global climate fears: the hole in the ozone layer. CFCs were phased out by the 1987 Montreal Protocol, an international treaty to combat ozone depletion, and eventually replaced by hydrofluorocarbons, or HFCs.

But HFCs have their own problem – they are greenhouse gases that are thousands of times more powerful than carbon dioxide in the short term. An amendment to the Montreal Protocol has set HFCs to be phased out dramatically by the mid-2040s; in the meantime, however, they continue to contribute to global warming.

There are many ways to make existing AC technology more efficient. Some newer AC units use different refrigerants, such as one known as R-32, which has less global warming potential than other hydrofluorocarbons and also takes less energy to compress, saving electricity. Other units use technology known as “variable speed compressors”, which allow the unit to run at different settings. The compressor can speed up if it’s 100 degrees Fahrenheit and swallow, or slow down if it’s only 85 degrees. It can help save electricity and electricity bills.

And more advanced models are just around the corner. Kalanki was one of the leaders of an initiative at RMI known as the Global Cooling Prize, which rewarded manufacturers who could produce affordable AC prototypes that would be at least five times better for the climate than existing models. Two companies received the award at the same time: Gree Electric Appliances and Daikin Industries. Both used traditional vapor compression technology, but with improved refrigerants and clever designs that could change settings in response to outside temperatures.

Other companies, start-ups and researchers are investigating whether they can ditch vapor compression altogether. A startup called Blue Frontier uses a liquid that sucks moisture from the air and stores it in a tank to control the temperature. According to the company, this approach can save up to 60 percent of the electricity required to run an AC year-round. And a group of researchers at Harvard University has developed an air conditioning prototype that they call coldSNAP. The prototype does not use refrigerant, but uses a special coating on a ceramic frame to evaporate water to cool the indoor space without adding moisture to the air. “Because we don’t have the vapor compression system and the energy to try to release and compress the refrigerants, the energy consumption of these systems is far, far lower,” said Jonathan Grinham, one of the researchers on the project.

Some of these new designs may take years to reach the market, and when they do, they may still be more expensive than conventional ACs. But in the meantime, says Kalanki, there are still many options for buying a more efficient AC unit.”There are technologies that are two to three times more efficient than the most common ACs on the market today,” Kalanki said. “The challenge is that adoption is very low.” Most consumers, he claims, look only at the sticker price of an air conditioner, ignoring the fact that buying a more expensive unit upfront can save them money in the long run.

He recommends that buyers look at three things when considering an AC unit: The type of refrigerant used, the efficiency rating, and whether or not the unit has a variable speed compressor. These calculations can tell consumers whether their device is likely to cost them thousands of dollars in utility bills down the road, and whether it will unnecessarily add to the problem of climate change.

Ultimately, he added, the government needs to set stricter performance standards for air conditioners so that all ACs on the market — not just high-end ones — are efficient and safe for the planet. “There are regulations in place to put the floor for air conditioning,” he said. “But that floor is a little too low.”

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