LEILA FADEL, HOST:
You may have missed it, but last December, Congress passed major climate legislation. It calls for slashing hydrofluorocarbons, or HFCs, over the next 15 years. One place these potent greenhouse gases are used is grocery stores. This switch away from them is already underway in California.
Laura Klivans of member station KQED in San Francisco reports.
(SOUNDBITE OF GROCERY SCANNER BEEPING)
LAURA KLIVANS, BYLINE: Every grocery store uses refrigerants to keep items frozen or cold. Refrigerants are gases that pump through thousands of feet of coils and pipes in meat displays, frozen cases, the cold juice section. How they work is a little counterintuitive.
ED ESTBERG: There's no such thing as cold.
KLIVANS: Ed Estberg is a refrigeration consultant for Raley’s supermarkets in California and Nevada.
ESTBERG: Absolute zero's -459.6. Anything above that has heat in it.
KLIVANS: Ice cream, for example - that's much warmer than absolute zero. Refrigeration actually removes heat.
ESTBERG: So you're just moving the heat away from the place where you don't want it to a place you don't care.
KLIVANS: Like cycling that captured heat out through the supermarket roof - but there's a problem with these gases.
DANIELLE WRIGHT: They're leaking.
KLIVANS: Leaking 25% a year, says Danielle Wright - she heads the North American Sustainable Refrigeration Council, an environmental nonprofit.
WRIGHT: The reason we got to these leaky systems isn't 'cause we can build a leakproof system. It's because it's not cost-effective to do so.
KLIVANS: Refilling refrigerants is just cheaper. The leaking doesn't harm a customer walking around the store. But it's really bad for the climate because of HFCs.
WRIGHT: HFCs, or hydrofluorocarbons, are the worst greenhouse gas that nobody's heard of.
KLIVANS: And they're everywhere - in AC units, vending machines, trucks driving food from place to place. They're the fastest-growing source of greenhouse gases globally.
Rob Jackson is a professor of earth systems science at Stanford.
ROB JACKSON: One large glass of HFC-134 has the same warming as a thousand pounds of carbon dioxide pollution from our cars. That's why it matters if it's leaking out, why it matters so much.
KLIVANS: Jackson says, while it's crucial to curtail carbon emissions, cutting HFCs is more straightforward. Plus, there's a lot of bang for your buck.
JACKSON: If we can phase out HFCs quickly, we'll reduce global warming by 1 degree Fahrenheit at century's end.
KLIVANS: In recent months, the U.S. has been moving in the right direction. A bipartisan federal law passed last December will cut HFCs by 85%, which will mean a different kind of supermarket, like this Raley's supermarket in Sacramento, with our refrigeration expert Ed.
ESTBERG: Well, this is just one of maybe 13 walk-in boxes where the refrigerated product is stored.
KLIVANS: It's HFC-free. Instead, it uses natural refrigerants, like ammonia, propane, even carbon dioxide, which may sound confusing. Carbon emissions are bad, right? Well, except when the alternative is hundreds to thousands of times more potent.
Here's Danielle Wright again.
WRIGHT: Natural refrigerants have zero or near-zero global warming potential.
KLIVANS: So when they leak, they don't damage the atmosphere nearly as much as HFCs. But building these stores is expensive. Supermarkets need to rip out and replace their whole cooling systems to switch over to natural refrigerants.
WRIGHT: Of the total number of grocery stores in the U.S., only 1% are using natural refrigerants.
KLIVANS: But that's a number that will change quickly, an example of policy working.
For NPR News, I'm Laura Klivans in Sacramento.
(SOUNDBITE OF TYCHO'S "EASY") Transcript provided by NPR, Copyright NPR.