Mark Koppang, Raley's director of sustainability, stands on the roof of a Raley's supermarket in Sacramento where heat from the market's refrigeration system is discharged. This market keeps their products cool using gases with near zero impact on global warming. (Laura Klivans/KQED)
Open your refrigerator. Take a look around the inside walls. See that label?
That is a record of the gas inside, and it’s responsible for keeping your food cold.
That gas is called a refrigerant, and refrigerants are found in everything from air conditioning systems to grocery store freezers, from industrial warehouses to Slurpee machines.
The majority of the gases used in refrigerants are hydrofluorocarbons, or HFCs. While they work well at keeping things cool, they have a significant drawback: they’re hundreds to thousands of times more potent a greenhouse gas than carbon dioxide.
Researchers at Project Drawdown, a nonprofit focused on how to cut greenhouse gases, say management and disposal of HFC refrigerants is the number one way to address climate change globally. Quickly phasing down HFC use has the potential to avert 0.5° C in warming by 2100.
“One large glass of HFC 134 has the same warming as a thousand pounds of carbon dioxide pollution from our cars,” says Stanford professor of Earth system science Rob Jackson, referring to one of the most commonly used HFCs. “It's really an amazingly potent greenhouse gas.”
If those gases were well-contained and disposed of properly at the end of their usable life, the high global warming potential of these gases may not have become a major concern.
But they are not contained. HFC refrigerants leak. The Environmental Protection Agency estimates supermarkets in the U.S. leak an average of 25% of their refrigerants annually.
Wright’s organization estimates that for the entire U.S., that’s roughly equivalent to the emissions from 12.5 million passenger vehicles driven for one year.
“The reason we got to these leaky systems isn't because we can't build a leak-proof system, it's because it's not cost-effective to do so,” Wright said. Refilling refrigerants is simply less expensive.
In California, HFCs account for 4% to 5 % of greenhouse gas emissions today, said Pamela Gupta, a manager overseeing HFC regulations at the California Air Resources Board. But the demand for refrigeration and cooling is growing as Earth warms, Gupta says: “They are the fastest growing source of greenhouse gas emissions in California, nationally and also globally.”
While the majority of the HFCs used in California are in air conditioning units, state regulators and academics see promise in addressing HFC use in supermarkets, given the large amount of refrigerant supermarkets use, and their high leak rate.
While experts agree it’s important to phase down all greenhouse gases quickly, some are harder to address than others; curbing HFCs is pretty straightforward.
“Replacing HFCs is much simpler than eliminating carbon dioxide pollution,” Jackson says. “We don't have to replace our entire energy and transportation sectors to get rid of HFCs.”
Refrigeration Isn’t What You Think It Is
To understand what refrigerants do, it helps to know a little about how they work.
Ed Estberg, a refrigeration consultant for Raley’s Supermarkets, knows quite a bit about the subject. His first job as a refrigeration mechanic apprentice was in 1962. He’s spent the decades since gaining expertise in the field. Nonprofit leaders to managers at competitor chains call him a master innovator.
Estberg says, to understand refrigeration, you’ve got to wrap your mind around something counterintuitive:
“There's no such thing as cold,” he says. “Absolute zero’s -459.6° F, anything above that has heat in it.”
Ice cream, for example, is much warmer than absolute zero. Refrigeration doesn’t actually cool something; it removes the heat from something you want to be cold.
“You're just moving the heat away from the place where you don't want it to a place you don't care,” Estberg said.
A place like the backside of your refrigerator, where it typically feels warm.
In a large supermarket, refrigerants speed through a pipe superhighway, cruising from ceilings down to refrigeration units, where they absorb the ambient heat circling your frozen peas, and travel skyward again, to a machine room above the ceiling.
Then, through a master stroke of engineering, the excess heat is discharged as steam or warm air — usually from supermarket roofs.
The refrigerants, ready to absorb more heat, then cycle back through the store.
Why We Use HFCs In the First Place
For most of the 20th century, the most widely used refrigerants were chlorofluorocarbons, or CFCs. CFCs are synthetic chemicals that were effective at keeping things cool, but had a treacherous side effect: ripping a hole in Earth’s ozone layer, threatening humans and all life with harmful ultraviolet radiation.
The Montreal Protocol was the first United Nations treaty to be ratified by all countries.
“It's one of the few things humanity's done collaboratively that actually worked,” says Project Drawdown senior research fellow Kevin Bayuk.
As CFCs phased out, HFCs became the common gases used for refrigeration.
Five years ago, nations in the Montreal Protocol, realizing the dangers of HFCs, gathered again in Kigali, Rwanda, to craft a new agreement. In what became known as the Kigali amendment to the Montreal Protocol, nations pledged to slash HFCs by more than 80% over 30 years.
In January, President Biden asked the Senate to ratify it.
Meanwhile, new federal and California laws already mirror the Kigali phasedown.
The Next Step Is a Look to the Past
To replace HFCs, grocery stores are turning back to what they used before synthetic refrigerants hit the market. These are called natural refrigerants because they’re found in nature and don’t have to be synthesized in a lab. They include ammonia, propane — and carbon dioxide.
“Natural refrigerants have zero or near-zero global warming potential,” says Wright of the North American Sustainable Refrigeration Council.
One reason companies moved away from natural refrigerants is that they have drawbacks: ammonia is toxic, propane is flammable, and carbon dioxide requires high amounts of pressure. That’s one reason stores that switch can’t simply put natural refrigerants into their existing systems. They have to rebuild the whole system of pipes and heat transfer.
Right now, not many stores have done this.
“Of the total number of grocery stores in the U.S., only 1% are using natural refrigerants,” Wright says. “If we were to move to, let's say, 10% adoption, that's equivalent to about six and a half million cars.”
The Supermarket of the Future
A high-ceilinged, natural-light-infused Raley’s supermarket on Freeport Boulevard in Sacramento boasts several climate-friendly features: efficient LED lights, a roof covered in solar panels, and a refrigeration system cooled by two natural refrigerants: carbon dioxide and ammonia. The CO2 circulates through the store, absorbing ambient heat, and the ammonia is used in the machine room above the supermarket floor, to keep it far from customers.
After more than 50 years building and adapting supermarket refrigeration systems based on changing refrigerant regulation, Estberg is hoping to build a system that lasts far into the future.
“We wouldn’t want to go through this again,” he says, “It’s expensive and it’s time consuming. And it takes a long time to perfect.”
Raley’s and other supermarkets are spurred on by a recent California regulation setting a limit on how much global warming potential is allowed in any new store construction. Currently, the only refrigerants that meet the requirement are natural ones.
Raley’s director of sustainability, Mark Koppang, says anything that can help supermarkets defray the cost of building a new system helps. An incentive program from the Sacramento Municipal Utility District helped fund the refrigeration system at the new Raley’s.
Would the company make the switch without regulation?
“There's a business decision to be made,” Koppang said. “I think there's a case to be made that we might not if we didn't have to. But that's a moot point now.”
What Individuals Can Do
Kevin Bayuk from Project Drawdown says there’s good reason to “to feel optimistic about refrigerants” in the fight to reduce greenhouse gas emissions. “But it does require at least a certain amount of people to put their attention on it.”
Here’s how you can do that:
While there are some efforts to push supermarkets to move away from HFCs, Danielle Wright of NASRC thinks that’s “misplaced effort.” Instead, she says, “consumers will have more impact pressuring their local legislators to support policies that incentivize low global warming potential solutions, fast-track innovative technologies, and support workforce training programs.”
Students at universities have created groups to address refrigerant management on campus, including recycling student mini-fridges. One example is at UC Berkeley, another is at Yale.
For people in the technology or financial sectors, Kevin Bayuk of Project Drawdown says there are ample opportunities for innovation to build appliances that accommodate non-HFC refrigerants, and for financing the transition away from HFCs.
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