The N.H.L.’s sustainability messaging now prominently features Chemours chemicals, but it wasn’t always that way. A league-issued “Greener Rinks” infographic on refrigeration systems from before 2018 endorses ammonia and carbon dioxide as natural refrigerants, saying that ammonia refrigeration systems have “significantly lower potential for ozone depletion and global warming” than HFCs and a predecessor, hydrochlorofluorocarbons, or HCFCs.
Matthew Rigby, an atmospheric scientist at the University of Bristol in England, said that the HFC refrigerants currently being marketed by the N.H.L. “weren’t the worst,” especially compared with compounds that were commonly used at arenas in the past. “They’re fairly nontoxic and they don’t deplete the ozone layer,” he said. “So obviously this is much more preferable, but they do still impact the climate.”
The major concern about ice rink refrigeration and similar systems is that they tend to be very leaky, said Alex Hillbrand, an expert on HFCs at the Natural Resources Defense Council, a nonprofit environmental group. “That system has a bunch of connections, like metal to metal joints, which can leak,” he said. “The chiller vibrates significantly as it’s operating. And vibrations over time cause small gaps to form.”
The refrigerants could also escape when these systems are ultimately disposed of, Hillbrand said, making it important for there to be programs in place to capture, collect and properly incinerate the gas.
Most scientists look at how much a substance warms the planet over 100 years to understand its effect on the environment, which is called its global warming potential. While the Environmental Investigation Agency and Chemours differ slightly on the numbers, they broadly agree that the first of two refrigerants marketed as Opteon warms the atmosphere about 600 times more than the same mass of carbon dioxide over a 100-year period; the second warms the atmosphere in excess of 1,200 times more.
Ammonia’s global warming potential is zero.
“You’re pushing facilities away from ammonia,” Hillbrand said. “That’s a step in the wrong direction.”
Chemours contends that Opteon is mostly used to replace the more harmful chemicals in older ice chiller systems, and that it reduces the global warming potential of those systems anywhere from 20 to 80 percent. Sueta, the company spokesman, said that Opteon was cost efficient for rink operators, and that while ammonia has no global warming potential, its production requires the use of fossil fuels.