The Montreal Protocol was designed to reduce ozone depleting substances which were affecting the earth’s protective ozone layer.
Since its inception in 1989, there has been an almost complete reduction in production and emission of ozone depleting substances (primarily refrigerants) and there has been measured evidence indicating some level of reversal in the size of the hole in the ozone layer above Antarctica in recent years.
Unfortunately, one of the problems not solved and in some cases made worse by the substitution of CFC/HCFC refrigerants with the current HFC refrigerants, is that the new refrigerants have not addressed the issue of very high global warming properties (GWP) – thousands of times more impact than equivalent weight of carbon dioxide.
So where is policy heading?
The next issue of focus is to now transition from high GWP refrigerants, to alternative refrigerants which have much lower GWP.
Australia and most of the other 196 countries that are parties to the Montreal Protocol reached a global agreement on reducing hydrofluorocarbon (HFC) emissions when they met in Kigali, Rwanda, from 10 to 14 October 2016. This is known as the Kigali Amendment to the Montreal protocol and its aim is to push industry to migrate from current refrigerants with 2000-plus GWP, to refrigerants with much lower GWP – HFO refrigerants with typical GWP of four.
The agreement stipulates an international phase-down of global HFC production and imports. The agreement aims for an 85 per cent phase-down in developed countries by 2036, an 80 per cent phase-down by 2045 in most developing countries including China, and the remaining developing countries reaching an 85 per cent phase-down by 2047.
Legislation was introduced in the Australian Parliament in March 2017, to implement a domestic phase-down of HFC imports. The Ozone Protection and Synthetic Greenhouse Gas Management Amendment Bill 2017 will phase down HFC imports starting in 2018 and reach an 85 per cent reduction by 2036.
Pathways to meet targets
There are a number of ways in which these targets can be addressed. On the refrigeration front, there are continuing improvements coming on to the market, utilising blended refrigerants which provide lower GWP but still retain reasonable coefficient of performance (COP). Degradation of COP to achieve lower GWP values is not a desirable outcome as it can lead to increased CO2 emission from electricity generation and places larger demand on electrical infrastructure.
The latest refrigerants now coming onto the market are hydrofluoro olefin (HFO) refrigerants. These have low toxicity, zero ozone depletion potential, low GWP and similar pressures to HFC 134a. As an example, HFO-1234yf has the potential to be used in current HFC-134a systems with minimal system modifications. So we may see this refrigerant being a dro- in replacement for existing operational chillers in the future.
There is continuing and growing uptake of natural refrigerants which can provide significant improvements in energy efficiency as well as provide low GWP and zero ozone depletion potential. Natural refrigerants most commonly used are ammonia, carbon dioxide, and hydrocarbons. These refrigerants are primarily used for specialist refrigeration applications.Some have challenges with toxicity or flammability, and some have challenges with operating pressures/vacuum.
It is expected that natural refrigerants will continue to gain market acceptance as alternative environmentally sustainable alternative refrigerants given the increased cost of producing the new breed of flouro based refrigerants, to meet the low GWP targets.
There has been significant development in thermoelectric cooling systems. This technology utilises electricity via semi-conductor materials to produce a heat flow effect (heat pump). This technology does not require a refrigerant to produce a heat flow effect and does not require a compressor or moving parts. The main disadvantage at this stage is that the efficiency of operation (COP) is much lower than conventional refrigeration systems.
The technology is already available and in use for specialist applications such as cooling of high output computing systems and some medical equipment. Further development of the technology should see increasing application possibilities for this technology.
Consideration for future projects
Below are a number of items to consider when considering cooling systems for your next project:
Consider what the expected life of the plant will be. The cost of HFC refrigerants will increase over the life of the plant, as has previously occurred with CFC and HCFC refrigerants, so consider adoption of lowest available GWP refrigerant or potential for drop in replacement refrigerant in the future.
Consider adoption of HFO refrigerants to ensure the plant can operate for its rated design life without the need for replacement or significant modification.
Explore natural refrigerant systems to see whether these can be utilised instead of the flouro based refrigerants. These will provide sustainability benefits including lower energy use.
Keep informed on advancements in thermoelectric cooling systems as a possible alternative to refrigerant based cooling for specialist applications such as high density IT equipment and specialist laboratory and medical equipment.
Always consider means of reducing or eliminating active cooling in a building by adopting good passive building design. This will bring much greater benefit in reducing greenhouse gas emission over the life of a building.