commentRefrigerants Pose New Climate Risk
A recent study from the National Academy of Sciences predicts so-called “green” refrigerants that replace ozone-depleting ones will contribute to global warming if left unchecked.
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Published last month in the Proceedings of the National Academy of Sciences, the study presents new data about modern hydrofluorocarbons (HFCs), which are considered greenhouse gases. The study claims HFCs could contribute the equivalent of 45 percent of carbon-dioxide emissions by 2050. Under that worst-case scenario, even if countries adopt a 450-ppm cap on CO2, “You still would have overshot it by about 50 percent,” says Mack McFarland, a scientist at refrigerant maker DuPont and the paper’s co-author.
Use of such HFCs as R-404a, R-410a and R-134a is set to grow as hydrochlorofluorocarbons (HCFCs), such as R-22, phase out under the Montreal Protocol. Starting in January 2010, manufacturers must stop producing R-22 for new equipment but may still make it for existing units. By January 2020, recycling will be allowed, but R-22 will be banned. During the 1990s, HCFCs were phased in to replace chlorofluorocarbons (CFCs), such as R-12.
Since then, ozone-depleting-potential levels in air-conditioning fluids have dropped to near-zero levels, but their global-warming potential, while lower than in the past, is now too high to ignore. Economic growth in established markets, as well as developing ones, such as Asia, are expected to boost HFC use. The paper concludes that the transition away from ozone-depleting fluids “has implications for future climate.” A cap-and-reduction program would help stem growth, McFarland notes, adding that DuPont and others are working on next-generation, low-GWP refrigerants, such as HFO-1234yf to replace R-134a for automobiles.
Low-ozone mandates, in addition to new tax rebates, are pushing owners to go geothermal. Yet, as rising heat-pump installations are expected to play a major part in HFC use—most new systems today use R-410a—heat pumps are set up to play a big part in global warming. There are now more than 600,000 GHPs installed in the United States, according to government statistics, and while this is the largest number for any one country, European nations have already surpassed the United States on a per-capita basis. The future is still bright for heat pumps, but they will likely require greener working fluids to solve future climate concerns.
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