R290 is replacing super-potent greenhouse gases in commercial fridges and freezers.

For a huge retailer like Target, with more than 1,900 stores nationwide, any enterprise-wide change is a big deal. Consider just its reliance on freezers and fridges. A typical store can have scores of such units, stocked full of frozen fare, fresh produce, dairy, and other perishable products. To sustain its fast-growing grocery sales, Target relies on tens of thousands of these condenser units.

A few years ago, the Minneapolis-based company began replacing the standard hydrofluorocarbon (HFC) refrigerant used in its freezers and fridges with a greener alternative: super pure propane, known as R290. In 2018 alone, Target installed more than 3,000 new stand-alone refrigerators and freezers running on R290. By 2021, the chain had installed some 15,000 HFC-free units, covering more than half of the systems in stand-alone cases, on the road to fully HFC-free refrigeration systems.

Target is a leader but it’s not alone.

Driven by a mix of sustainability goals and evolving regulations, grocers in the US and Europe are at the front of a wider shift away from coolants that damage the ozone layer, the climate, or both. And R290 is emerging as a reliable and affordable option, with low greenhouse (GHG) impacts. Other major grocery chains including Whole Foods and Aldi are likewise swapping in propane-powered freezers and fridges across their networks.

The family of HFCs that retailers are carefully extracting from their chillers have a global warming potential (GWP) — a measure of how destructive a climate pollutant is — in the thousands, compared with 3 for R290 and 1 for CO2. By comparison, today’s most common HFC refrigerant, R-22, has a 100-year GWP of 1,810. HFCs routinely leak during manufacturing, from poor seals, and/or during disposal, so even tiny wisps of escaped HFCs can have an outsized climate impact.

Fixing ozone first

The roots of this switch go back to Obama-era climate policy. In 2015, in a landmark move by the Environmental Protection Agency, the federal government mandated the retirement of a long-serving family of HFC coolants, to be replaced with a handful of so-called fourth generation alternatives, including R290 propane, with dramatically lower GHG emissions.

HFCs first emerged as a solution to an earlier environmental crisis: the growing ozone hole. Beginning in the 1960s, scientists began to recognize that leaks of so-called second-generation coolants — chlorofluorocarbons (CFCs), then used widely in everything from hair spray cans to refrigerator coils — were destroying a protective layer of the upper atmosphere, creating a zone of missing ozone over the South Pole. Absent action, declining ozone threatened to expose people, plants, and animals to damaging levels of ultraviolet radiation.

The crisis triggered an unprecedented international mobilization. The 1987 Montreal Protocol banned the use of CFCs and set the stage to replace them with HFCs. The plan worked better than anticipated. CFC levels have fallen steadily and the ozone layer is on track to recover by the 2030s.

Yet this effort to fix the ozone hole had unintended consequences by exacerbating the climate crisis. For all the success HFCs have had in healing the ozone, their role in climate change was little understood in the era when they were chosen. In the years since, the climate crisis has come to the fore and HFCs have been identified as powerful greenhouse gases.

As part of wider global efforts to reduce emissions of climate warming gases, CO2 remains the first focus of companies and policy makers, but other exotic gases — such as fluorinated compounds like HFCs and nitrous oxides — are coming under increased scrutiny, too. Given their high global warming potential — from tens to thousands of times that of CO2 — removing them makes possible significant, relatively quick reductions.

That’s why state, national and global efforts to shift away from HFCs are gathering pace. In January 2021, the White House took steps for the US to ratify an update to the Montreal Protocol, backed by over a 120 countries as well as US industry, that will ramp down HFC production. And in September 2021, the EPA formally implemented a 2020 law mandating the reduction of US HFC production by 85% over the next 15 years. By mid-century, the move will avoid the equivalent of 4.6 billion metric tons of CO2, the EPA estimates — equal to about three-quarters of total US emissions in 2019.

Propane returns

The wind down of HFCs is opening the door for fourth generation coolants such as R290. And for propane, the shift marks a return to the past, when propane was among the top options at the dawn of mechanical refrigeration.

In 1922, for example, propane was pitched as an “odorless safety refrigerant.” Around the time GE introduced the first household refrigerator, other first-gen coolants included highly pungent blends of ammonia and sulfur dioxide. Today, the propane and natural gas we use at our homes are chemically odorized with a derivative of sulfur so any leaks are noticed quickly.

While produced in similar facilities, R290 is purposefully de-odorized to achieve near complete chemical purity. Where household propane is typically blended to around 90% purity, R290 is refined to greater than 99% to deliver maximum efficiency in refrigeration systems.

Propane’s flammability, combined with the absence of any warning odor, limits its use to commercial applications where professional installation and careful monitoring minimize the risk of leakage, explains Bryan Cordill, director of residential and commercial business development at the Propane Education & Research Council.

In a nod to safety, the propane-based systems used to chill freezers and fridges at Target and other US grocers are limited to 150 grams of propane per condensing unit. A typical aisle of freezer cases would use a series of such units to keep temperatures icy.

Europe, which began shifting away from HFCs ahead of the US in 2015, increased the charge limit of R290 from to 500 grams from 150 in 2019. Industry watchers contend that, in time, US regulations could follow suit.

Niche market, big impact

For the overall propane market, R290’s emergence amounts to a tiny sliver of specialized demand. Given the small volumes of R290 used in each system – grams versus pounds — only a handful of US refiners produce the refrigerant. It’s high purity and limited quantity production profile means a 20-pound tank of R290 can cost roughly eight times that of conventional propane.

All the same, as cooling technology continues to shift away from CFCs and HFCs, the impact of fourth-gen coolants such as R290 should help limit global warming. According to a recent study in Nature, the Montreal Protocol has already avoided enormous climate change impacts. CFCs are super potent warming agents in their own right — some with GWPs of 10,000 or more.

Further, by avoiding anticipated damage to forest lands and other vegetation had the ozone layer collapsed, the move protected countless CO2-sequestering trees and other foliage. Combined, the shifts away from CFCs and HFCs promises to stave off a potentially massive amount of warming — an additional 2.5°C by the end of this century, the analysis estimate.

To date, the world is some 1.2°C warmer than pre-industrial historical averages and under current policies, the world is on track to experience 2.9°C of warming by 2100. The U.N. has identified 2°C as a critical threshold beyond which catastrophic destabilization of the economy, ecosystems, and weather is more likely.

By playing a part in the push to cut emissions while also protecting the ozone layer, R290 is playing a key role in protecting the climate.