The Environmental Journal of Southern Appalachia

Oak Ridge National Laboratory helps keep our cool as refrigerant restrictions begin

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2015 P00418Brian Fricke, group leader for Building Equipment Research, conducts testing in his refrigeration system research lab at Oak Ridge National Laboratory. Jason Richards/ORNL

ORNL pursues refrigerant efficiencies and alternatives as we warm the Earth to keep things cold

You can flick it off; it’s cool.

Finally there’s a window, literally, for the annual retirement of your air conditioner. But the freezer aisles at your favorite supermarket aren’t going anywhere.
As summer slowly slips into autumn and we aspire to warm ourselves through winter, let’s consider the cost, economically and environmentally, of keeping ourselves under blankets in August or loading up on frozen burritos on a broiling day inside the deliciously cool air of a grocery store freezer aisle.
Let’s cast a cold eye toward Oak Ridge National Laboratory, where engineers are developing improved storage and transmission techniques to limit the harrowing climate-change effects of coolants and refrigerants, even as new pollution restrictions come into effect.
Coolants have played a role in environmental change and global warming since the very advent of the crudest cooling devices
Refrigerants have even driven human-settlement patterns and development of areas with harsh, hot climates such as the American South and Southwest. They’ve been rough on the Earth’s atmosphere and played an oversized role in climate change.
It’s kind of complicated:
Chlorofluorocarbons (CFC) used in 20th-century cooling and refrigeration systems thinned the ozone layer.

Then the hydrofluorocarbons (HFC) that replaced them turned out to be greenhouse gases that in some cases were 4,000 times more potent than carbon dioxide, itself a powerful driver of climate change.
The recent federal climate change directive requires an 85-percent phaseout of HFCs over the next 15 years.

So what will replace those coolants as heat waves associated with climate change only increase, in the near-term at least, the use of refrigerators and air conditioners across the world?

Scientists and engineers at ORNL are working on the next generation of coolants — and the efficiency and safety of their delivery systems — as HFCs are phased out.

The scale and potential impact of the ORNL effort is vast: Consider how many air conditioners and refrigeration systems you encounter regularly, especially during trips to the supermarket, where invisible refrigerant lines cool everything from produce to frozen pizzas.

Those supermarket lines — and compressors and pipes — leak an estimated 25 percent of their coolant into the atmosphere every year, according to Brian Fricke, a group leader for building equipment research at ORNL who specializes in retail cooling.
The coolant known as R404A, commonly used in supermarket systems, can be 4,000 times more potent as a greenhouse gas than carbon dioxide (the “global warming potential” of certain gases has a baseline of 1, which represents carbon dioxide), Fricke said.

The use of that coolant, aside from reclamation purposes, was banned beginning in 2020 in the European Union. In the U.S., the coolant is set for phaseout by 2030.

Supermarket cooling infrastructure is just one source of the pollutant.

“Think about air conditioners, heat pumps, refrigerant charge … if you sum all those millions of units up, residential, commercial, industrial sector,” the climate-change effects are vast.

“What we’re trying to do is develop energy-efficient and low-emission equipment,” he said, and the Building Equipment Research Group focus ranges from water heaters to heat pumps and refrigeration.

He spoke to Hellbender Press in a Zoom interview about his group’s work, but first wanted to provide a history lesson about the toxic and somewhat haphazard and dangerous development of refrigerants beginning in the late 1800s.

“There were some fairly nasty chemicals, that were used as refrigerants, like methyl chloride, like sulfur dioxide, and and maybe some more familiar ones, like ammonia and carbon dioxide,” he said.

(More irony: carbon dioxide, the climate change poster child, is a quality coolant that is the subject of increasing research and use).

The cooling process was stabilized somewhat over the decades to the point that refrigerators became a more common feature of homes and businesses, but coolants still had widespread toxicity and flammability issues. 

In the 1930s, an engineer with General Motors’ Frigid Air division introduced a new refrigerant that harnessed CFC for its cooling properties. It was ultimately marketed under what became a familiar trade name: Freon. An old tale still survives of the engineer, Thomas Midgley Jr., inhaling Freon to prove its safety to interested clients.

The problem was, and it wasn’t noticed until decades later, chlorine damaged high-level ozone, one of Earth’s shields against solar damage that makes the planet hospitable to life.

In a further cycle of irony and alphabet soup, the HFC that replaced the CFC (the chlorine molecule was replaced with a hydrogen molecule) were extremely potent greenhouse gases.

Those gases, most notoriously carbon dioxide, “are gases that will absorb radiation from the sun and then reemit that typically in the infrared area,”   Fricke said.

“If we have a lot of types of those gases in the atmosphere absorbing and then reemitting the radiation at a different wavelength … then we’ll experience heating of the planet.

“What we’re trying to do is develop energy-efficient and low-emission equipment,” he said, and the group’s focus ranges from water heaters to heat pumps and refrigeration.

In terms of refrigeration systems, the group’s focus is on ensuring the coolant stays contained and that minimal amounts are needed in the first place.

One efficient coolant suggests that “what once was old is new again,” Fricke said in reference to the revival of carbon dioxide as a refrigerant. Its GWP is 1, as mentioned above, which means it’s a relatively benign greenhouse gas compared to refrigerants such as R404A  .

Fricke said some new supermarkets in the Atlanta area now use a CO2-powered refrigerant system, which can also be used in tandem with ammonia to improve cooling efficiency,

Gases such as butane and ammonia and even a new class of molecule (hydrofluoroolefins) offer more benign refrigerant alternatives for the future, and Fricke’s team is pursuing all possibilities, including how to safely deliver and contain the emerging new coolant classes.

“There are issues with these new refrigerants?” he said, such as toxicity and flammability. A main concern is “how can we design equipment that can safely use these refrigerants?”

And in the case of carbon dioxide for use as a commercial-level coolant, it must be delivered via high pressure through an especially “robust” pipe system.

“Throughout the whole history of refrigeration, we’ve been looking for silver bullets, but there is no silver bullet. There are always tradeoffs, in terms of performance, flammability, toxicity and now we can add impact to the environment to that, as well.”  
This story has been corrected: Ammonia is not a hydrocarbon.
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