New Science Highlights a Curious Case of HFC-23

A new scientific study has uncovered a vast increase in atmospheric levels of a powerful climate pollutant called HFC-23, a hydrofluorocarbon with more than 12,000 times the heat-trapping power of carbon dioxide. The authors calculate that global HFC-23 emissions have wildly exceeded projections recently, costing our carbon budget as much as building 26 new coal-fired power plants.

HFC-23 is mainly produced as an unwanted byproduct of making another chemical, HCFC-22. A majority of the world’s HCFC-22 plants (accounting for two-thirds of world production) are located in China, but there also appears to be significant HCFC-22 production in other countries with fluorochemical industries, such as several in Europe, India, Japan, Russia, and the United States.

Surprisingly, global HCFC-22 production is still on the rise. Production of that chemical for use as a refrigerant or for other end uses is being phased out under the Montreal Protocol, the treaty to save the ozone layer. But that phase-out is not yet complete in developing countries.  More importantly, the treaty allows companies in all countries still to produce unlimited amounts of HCFC-22 indefinitely, as a “feedstock” ingredient for making other products. There’s no deadline to end feedstock production. 

A plant with HFC-23 incineration. CCM Data and Business Intelligence

Many HCFC-22 plants in developing countries are equipped with incinerators to destroy the HFC-23 byproduct. Indeed, the plant owners were paid handsomely through international emissions trading markets to install those incinerators about a decade ago. Although those payments were far larger than needed, they did get many incinerators installed and operating. The credit program for HFC-23 ended by 2014, and it now seems that some of the plants have stopped running their HFC-23 incinerators.

It’s unclear just how much HFC-23 is being released from HCFC-22 plants in developed countries. It’s even unclear just how much HCFC-22 is being made in each of those countries in the first place, because those reports to the Montreal Protocol are kept largely confidential.

That scientists have now detected a big spike in atmospheric concentrations of HFC-23 strongly suggests that some plants have simply turned incinerators off and are releasing this super-pollutant directly into the atmosphere. There may also be new HCFC-22 plants that don’t have destruction technology installed at all. Some plants may even be illegal – that is, they may have been constructed and operated without reporting under the Montreal Protocol, even though the treaty requires countries to identify and report on all HCFC-22 producers.

Installing and using incinerators is the best practice for destroying HFC-23. It is required by national laws in many countries. The incinerators are cheap to run, costing just tens of cents per ton of carbon dioxide equivalent avoided. But some plant operators may be looking to cut costs by idling them.

The team of scientists, led by the University of Bristol, point to China and India, the developing world’s top two producers, as the likely sources for a substantial slice of the unexpected emissions. Both countries have committed to limit these emissions. In 2016 India decreed that no HCFC-22 producer may emit HFC-23. China promised to the Montreal Protocol’s Multilateral Fund that it would implement best practices for HFC-23 management and has a patchwork of such requirements. In 2018, China reported to the Fund that it successfully destroyed 99.8% of HFC-23 byproduct (the study considered the period 2015-2017, so the reports don’t directly conflict).

Both countries have also been constructive partners in the global effort to begin phasing down HFCs under the Kigali Amendment. China has made great strides in rectifying a recent spurt in emissions of CFC-11, a different gas controlled by the Montreal Protocol—apparently by strengthening enforcement of its domestic CFC phase-out laws. India adopted a Cooling Action Plan in 2018 to cut down on fast-growing demand for hydrofluorocarbon refrigerants while meeting its growing need for cooling.

All countries home to HCFC-22 manufacturing—including in the U.S., Europe, Russia, and Japan—would do well to verify that factories reporting on HFC-23 destruction, whether voluntarily or mandatorily, are providing accurate accounts. These emissions also call for greater commitment by all countries to eliminate HFC-23 emissions. HFC-23 destruction is mandatory for parties to the Kigali Amendment to the Montreal Protocol, the 2016 global agreement to phase down HFCs. Although 92 countries have ratified the Kigali Amendment, the United States, China, India, and Russia have yet to ratify.  

The scientific community should follow up with more detailed atmospheric measurements and modeling to help pinpoint the sources of the emissions, as was done to chase down the unexpected CFC-11 emissions. There are monitoring sites within range of most countries with fluorochemical production, but some additional monitoring stations are needed, including near India, to help governments better understand emissions from within their borders. The possibility that rogue HCFC-22 plants are contributing to the problem strengthens the case for adding to the monitoring network in a number of regions worldwide.

Scientists and diplomats have long worked cooperatively under the Montreal Protocol to identify and curb problematic fluorocarbon emissions like the ones we’re seeing today. HFC-23 has always been a curious case, and the time has come to tackle it once and for all.

About the Authors

Alex Hillbrand

HFC Expert, Climate & Clean Energy and International Programs

David Doniger

Senior Strategic Director, Climate & Clean Energy Program

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