Limiting HFCs and Replacing Them with Other Coolants, Often Natural Gas Liquids-Based Hydrocarbon Refrigerants

Limiting HFCs and Replacing Them with Other Coolants, Often Natural Gas Liquids-Based Hydrocarbon Refrigerants

The 1987 Montreal Protocol successfully banned the use of chlorofluorocarbons (CFCs) as refrigerants, or coolants. CFCs were eating a hole in the stratospheric ozone layer as well as making a serious contribution to global warming since CFCs are an extremely powerful greenhouse gas. The phase-out of CFCs has indeed stopped the hole from growing and it has ‘healed’ some. Since then one of their main replacements was hydrofluorocarbons (HFCs) which do not affect the ozone but HFCs are still a powerful greenhouse gas, though less so than CFCs. Climate scientist James Hansen once quipped that if we moved to another planet and wanted to create habitable temperatures we could create an atmosphere by increasing greenhouse gases and to do so we could just start a couple CFC-generating factories.

A new global agreement was recently reached on Oct. 15, 2016 in Rwanda to phase-out HFCs in favor of other refrigerants. This is necessary especially since electrification and subsequent refrigeration is increasing throughout the developing world and is expected to continue to increase. The main goal of the Rwanda deal is to bring usage of HFCs down 80-85% by 2047, which could theoretically prevent as much as 0.5 degree Celsius warming by 2100. The EU banned the use of HFCs in cars in 2011. Most HFCs are made by big Western chemical companies so phasing them out should be easy from the source. However, fast developing countries like China, India, and Pakistan have been expanding air conditioning and refrigeration massively and so have previously resisted attempts to phase out HFCs. The U.S., Japan, and Europe will begin phasing out HFCs in 2019 but India, Pakistan, and China have negotiated a later phase-out beginning in 2024 in China and 2028 in India. 

From the Guardian article:

“The new agreement is welcomed by many chemical and manufacturing companies because it gives them green kudos and market advantage over inferior products made in poor countries.”

“But it was much harder for India, China, and other developing countries to strike a deal. Their companies have relied on old refrigeration and coolant technologies, and will now have to invest in R&D and upgrade or replace factories and equipment.”

New alternatives to HFCs are widely available, safe, energy-efficient, and inexpensive.

Car air conditioners typically use HFO-1234yf and those molecules break down relatively quickly in the atmosphere drastically reducing the global warming potential (GWP) although there still is some. One replacement for freezers, R-134a, also has a much smaller global warming potential (GWP) than CFCs and HFCs. However, it also makes a freezer or refrigerator run less efficiently and when the extra energy use is added, much of the global warming advantages are cancelled out. Propane-based R-290A has been a successful replacement for R-134a as hydrocarbons like propane are very efficient. Hydrocarbons that trap less heat such as butane, isobutane, ethane, propane, propylene, and various blends, all derived from natural gas liquids or petroleum refining, are also used fairly extensively. They are projected to become the main alternative in the future for home and light commercial use and already are in much of the world. Their global warming potential is miniscule compared to the others and they do not affect the ozone layer at all. They are efficient and low cost for domestic and light commercial applications but higher cost for industrial refrigeration applications due to the need to safeguard against the higher explosion risk. There are some safety concerns due to their flammability but these are thought to be minimal, especially when potential ignition sources within appliances are properly avoided by good system design and when charged low so that if leaked they will not exceed the limits to flammability. Alternatives other than hydrocarbons are CO2, ammonia, and natural methods using air and water that are high in cost and take up too much space. R&D continues. CO2 and ammonia combinations are being used in large commercial apps although ammonia has toxicity issues. 

According to the Danfoss white paper (Danfoss is a world leader in HVAC/R system design) HFCs in North America are still the main refrigerant for household and light commercial applications compared to the rest of the world which uses hydrocarbons mainly. This is expected to change as the protocol is implemented in 2019 and by 2025 hydrocarbons are projected to be the main refrigerant for such applications in North America. Hydrocarbons are apparently less suitable for use as air conditioning coolants and so most of the transition from HFCs in this app is expected to be to other HFCs and HFOs with GWPs below 700, except in China where hydrocarbons are projected to be the main A/C refrigerant by 2025. The problem with using hydrocarbons (and some low GWP HFCs) in larger industrial applications and (presumably) A/C units is the need for higher charges which increases the flammability and explosion hazards. 

In the future there will even be bans on servicing equipment with high-GWP refrigerants. This will be part of the later phase-out process. 

References:

Wanted: New Ways to Chill Air Conditioners, Fridges – by Thomas Sumner, in Science News, Oct. 25, 2016

Kigali Deal on HFCs is Big Step in Fighting Climate Change – by John Vidal, in The Guardian, Oct. 15, 2016

Hydrocarbons – from www.refrigerants.danfoss.com 

Refrigerant Options Now and in the Future: a white paper on the global trends within refrigerants in air conditioning and refrigeration seen from a Danfoss perspective: Achieving sustainable HVAC/R through intelligent solutions, energy efficiency, and low GWP refrigerants – www.refrigerants.danfoss.com