For One Vexing GHG Problem, A Simple Solution Proves Effective

One of the most vexing long-term challenges in reducing greenhouse gas emissions lies quietly outside the cacophony surrounding things like automobiles, electric generation, and oilfields. It’s refrigeration, and while often overlooked, it is a critical industry that is trying to adapt as the world increasingly takes measures to rein in greenhouse gas emissions (GHGs).

Addressing a Long-Term Problem

Refrigeration has long relied on a group of effective but problematic gases called CFCs and HFCs as its base ‘refrigerant’ – the fluid used to absorb heat from the inside of your refrigerator and move it to the outside, keeping things cool. Chlorofluorocarbons (CFCs) have a habit of destroying ozone and have been largely phased out because of it. They have been replaced in recent years with hydrofluorocarbons (HFCs), which, while ozone-friendly, can have warming impacts scientists say are up to 10,000 times greater than carbon dioxide.

This wouldn’t matter much in a closed system, as refrigeration units are designed to be, but the reality is that all cooling systems tend to suffer fairly high leakage rates, allowing whatever refrigerant they’re using to eventually escape into the atmosphere. Given that a typical HFC molecule produces a heat-trapping effect thousands of times more potent than carbon dioxide, it doesn’t take a lot of the gas in the atmosphere to result in a significant impact. Thus, there has been an ongoing search for a replacement for HFCs.

One of the more promising solutions initially looked to be switching to carbon dioxide (CO2) as a refrigerant. While that may seem counterintuitive with today’s hyper-focus on reducing atmospheric CO2, it is essentially a carbon-neutral solution and certainly better than something with 10,000x the warming potential of CO2.

However, as KC Chen, Vice President-CO2, for industrial technology developer Energy Recovery
ERII
described for me in a recent interview, there is a catch in making the substitution. “The catch is that at high temperatures, the efficiency for legacy CO2 systems dropped rapidly,” he says.

As Chen describes it, the problem with leakage is especially prevalent in industrial and commercial refrigeration, such as in the frozen food sections of big grocery stores. “A typical supermarket has an annual leakage rate of about 18%,” Chen says. “That’s why they are especially focused on using CO2 as a replacement. For CO2, the global warming potential is low, but as you reach temperatures of about 20-25 degrees Centigrade (68-77 degrees Farenheit), then suddenly, the efficiency drops.”

When that efficiency factor drops, the cooling system must consume more and more energy to hold temperatures down. This leads to dramatic increases in costs and emissions, rendering the entire system less productive and sustainable.

This is why switching to CO2 has not yet become a widely adopted practice. A second solution was needed to address the efficiency of the CO2 system itself.

An Elegant Solution to a Vexing Problem

To that end, Chen and the team at Energy Recovery have developed an elegant pressure exchanger technology that does the trick. It is a technology the company has already successfully deployed in a variety of other applications, including desalination and industrial wastewater operations.

The concept is simple: The pressure exchanger, a compact modular unit, functions like a piston that enables the transfer of energy in a CO2 system from high pressure to low pressure, without mixing the fluids on either side, maximizing the system’s efficiency. By conserving pressure energy within the system, less power is needed to run it.

By incorporating the pressure exchanger into CO2 refrigeration, Chen says “we can improve the efficiency of the system by around 30%. That can actually bring CO2 back to par with HFC at extreme high temperature.”

Deployment of the pressure exchanger can also save capital costs, since, as Chen points out, industrial and commercial users have been designing their systems to accommodate for this loss of CO2 efficiency at high temperatures. “That’s created a lot of waste,” he says. “But you don’t need to do that [with the pressure exchanger installed] because once you put it in, you are addressing the efficiency issue.”

“This whole thing is all about saving energy.”

From Chen’s perspective, the development and deployment this kind of technological solution is needed to enable the world to continue to enjoy a modern way of life. “Really, this whole thing is all about saving energy,” he points out. “Because unless we as human beings want to go back to a more rudimentary lifestyle – which we can do – but if we want to maintain our current lifestyle, the only way I believe we can do it is to use the energy we have much more efficiently.”

International climate agreements and looming regulatory actions will work to ensure all of the world’s citizens face this choice in the coming years. As Chen pointed out in our interview, 197 countries have signed onto the Kigali Amendment to the Montreal Protocol, which mandates an 80% reduction in the use of HFCs by 2046. In the U.S., states like California and Washington are moving on much quicker timetables, as are many countries in Europe.

That regulatory pressure to act soon likely factored into the recent decision by Epta Group, a European company that specializes in retail commercial refrigeration, to partner with Energy Recovery to integrate pressure exchanger technology into their latest refrigeration system.

Although Energy Recovery has deployed its technology in the U.S. market too, there is a recognition that, as a whole, the European market is moving faster towards HFC reduction. “In the European market, adoption is faster because regulators there are moving more quickly,” Chen says. “And it’s not just HFC regulation, they also have requirements on energy reduction. So, that just basically makes the whole thing much more straightforward and aligned with our technology’s value proposition.”

Bottom Line

Achieving the world’s net-zero by 2050 goals will require the development of a wide variety of technological solutions to address what are often incredibly complex and vexing problems. Energy Recovery’s pressure exchanger shows that technology can get us there without taking an economic step backwards.