It’s both ironic and frightening that the chemical compounds used to produce the cooling effect we so enjoy in an air-conditioned building and our fridges and freezers have some of the most potent effects on global warming.
Supermarkets have colossal environmental footprints and contribute to the climate crisis in several ways. A significant and avoidable part of their climate impact lurks in their refrigerated aisles. Supermarkets across the country are leaking refrigerants, greenhouse gases thousands of times worse for the environment than CO2. A single supermarket emits 875 pounds of hydrofluorocarbons (HFCs) each year, equal to the carbon dioxide emitted by more than 300 cars. Given that there are over 38,000 supermarkets in the United States, these leaking emissions are equivalent to burning 49 billion pounds of coal... every single year.
Brief History of Refrigeration Gases
Before 1987, refrigeration systems used chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). After they were found to deplete the ozone layer, CFCs and HCFCs were phased out through the Montreal Protocol. They were primarily replaced with HFCS, touted for having a minimal deleterious effect on the ozone layer. Unfortunately, despite the negligible ozone effect, HFCs can still warm the atmosphere up to 9,000 times more than carbon dioxide. In October 2016, more than 170 countries agreed to an amendment of the Montreal Protocol which began phasing out HFCs in 2019. Unlike the Paris Climate Agreement, this amendment is mandatory with specific targets and timetables for actions. John Kerry called it “The biggest thing we can do on climate in one giant swoop.” Scientists estimate the accord will reduce global warming by nearly one degree Fahrenheit.
Hydrofluorocarbons, or HFCs, are the predominant compound used in modern appliances to absorb and release heat, the basic process behind refrigeration. In May 2021, the Environmental Protection Agency (EPA) proposed a rule to limit the use of HFCs using a cap-and-replace system. This rule, which has already begun to take effect in 2022, is projected to reduce emissions substantially by 2050. All told, the EPA anticipates that the rule could lead to reductions equivalent to 4.7 billion metric tons of carbon dioxide, or the same amount produced by the entire U.S. power sector over three years.
In the book Drawdown, Paul Hawken lists refrigeration management as the number one solution to making the biggest impact on Climate Change. This solution involves reining in HFCs, which are super-potent greenhouse gases, and Drawdown estimates that 90 gigatons of carbon dioxide can be avoided.
The good news is this problem is fixable, and grocery stores across the nation are starting to act towards eliminating leakage and, in many cases, switching their refrigeration systems to CO2 or other natural refrigerants – which have a very low GWP.
Commercial refrigeration systems used in grocery stores are highly susceptible to lose components and refrigerant leakages. These systems have lots of complex piping. Any improper installation, maintenance, or tightening can result in loose or broken fittings, which weaken connection points and allow for leaks. The mechanics of a refrigerator, which operates by expanding and contracting refrigerant under pressure, adversely affects the integrity of seals. Vibration and regular wear and tear itself can exacerbate leakages. For these reasons, it is nearly impossible to have a system that will never leak in its lifetime.
Refrigeration systems leak harmful gas every year, and that leaked volume must be replaced. The cost of replacing these HFCs has increased significantly, which has helped incentivize grocery stores to, at the very least, install leak detection systems – and, in some cases, convert to CO2 or other natural refrigeration systems.
The average supermarket system contains thousands of pounds of refrigerant, and, depending on the refrigeration system used, leaks an average of 20-25% of its refrigerant each year. The North American Sustainable Refrigeration Council (NASRC) states this adds up to “70 million metric tons of CO2 equivalent emissions each year just from supermarket refrigeration leaks. That is equivalent to the emissions from powering 12 million homes, which is roughly the number of households in the state of California.”
Beyond environmental costs, there are additional significant financial costs associated with refrigerant emissions. Lost refrigerant needs replaced once the leak has been fixed–and with spiraling refrigerant costs due to the AIM Act phase-down, as well as supply chain constraints, this is a constant challenge. What’s more, when refrigerant charges are below the optimum level, the equipment requires more electricity to maintain operations – adding extra financial costs and CO2 emissions. Additional financial costs of spoilage, lost sales, and customer dissatisfaction can occur as well.
Refrigerants currently cause emissions throughout their life cycles – in production, filing, service, and when they leak. Their damage, however, is greatest at the point of disposal. Ninety percent of refrigerant emissions happen at end-of-life. If the chemicals are not disposed of effectively, they escape into the atmosphere and cause global warming. Refrigerant recovery has immense mitigation potential. After being carefully removed and stored, refrigerants can be purified for reuse or transformed into other chemicals that do not cause warming.
Transitioning to a Low GWP system
Managing the refrigerant that is used is essential to reduce the climate impact of these systems; an even more effective solution, however, is to discontinue the use of high-GWP gases altogether. Commercial refrigeration is one of the most advanced cooling sectors when it comes to adopting climate-friendly refrigerant solutions. The barriers to adopting better, climate-friendly technology in this sector are less pronounced than in other cooling applications. In fact, in Europe ultra-low GWP natural refrigerants are the new standard for supermarket builds, with over 26,000 supermarkets using trans-critical CO2 technology, not to mention those using hydrocarbons, ammonia, or other system types. This is in stark contrast to the barely 600 known stores in the U.S. using the same technology.
Global demand for commercial refrigeration equipment is forecasted to increase dramatically. Many commercial refrigeration systems in use contain ozone-depleting refrigerants chlorofluorocarbon (CFC)-12, hydrochlorofluorocarbon (HCFC)-22, and R-502, which are being phased out globally under the Montreal Protocol. Many new units sold today contain HFCs and HFC blends, namely HFC-134a, R-404A, and R-507A, with GWP values of 1,430, 3,920, and 3,985, respectively. Many lower-GWP alternative refrigerants are available and currently in use or under development for use in commercial refrigeration.
Part of the Whole
If just one grocery store switches their cooling system to transcritical CO2, they avoid the same amount of emissions as are generated by 41,400 flights from LA to NYC. Switching one, average grocery store to CO2 has the same environmental impact as grounding 41,400 cross country flights.
When we take this to a nationwide level, the impact is astounding. If every grocery store in the United States converted their systems to transcritical CO2, it would have the same environmental impact as if 79,395,000 people committed to live a net-zero lifestyle. If you could wipe out the carbon footprint of a population 9.5 times as big as New York City, that’s the equivalent of all grocery stores switching to transcritical CO2.