There Are Differences Between Heat Pumps

Heat pumps offer energy efficient cooling and heating, but their environmental impact is more complex. The sustainability of a heat pump cannot be defined without taking into account the refrigerant used in it.

Valtteri Haavisto, Technology & Development Director at Vahterus

Renewable and low-emission energy are topics that have dominated the debate on energy production in recent years. Rapid change has brought a vast number of new solutions onto the market, and has necessitated and driven technological development.

Heat pumps are part of the new energy solutions. Households are changing their heating systems to heat pumps, and the same trend can be seen on an industrial scale. Energy companies have increasingly been adding heat pumps to their products. The efficiency of industrial heat pumps enables the effective utilisation of waste heat from several sources and brings it to a higher temperature. New heat pumps have also made it possible to use air or seawater as a source of heat, which was previously thought to be impossible. However, the refrigerants used in heat pumps are a topic that is often excluded from these studies.

The compressor in a heat pump takes the pressure of vaporised gas to a higher level, enabling heat transfer between the refrigerant and user of the heat. The same refrigerants are used in the housing, food and transport industries in countless applications, and their total volume is millions of tonnes. Refrigerant leaks from systems are also huge.

The troubled history of refrigerants is as follows:

• 1834: A refrigeration system based on compressed gas is invented. Ammonia or water is used as the refrigerant.
• 1930–1950: The first synthetic CFC refrigerants (R12) are developed.
• 1960–1987: New synthetic HCFC refrigerants (R22) are developed.
• 1970: It is discovered that CFC and HCFC refrigerants cause ozone depletion.
• 1987: A global agreement, the Montreal Protocol on CFC and HCFC is introduced to reduce the use and production of refrigerants that cause ozone depletion.
• 1987–2015: New synthetic HCF refrigerants are developed and used (R23, R32, R134a, R404a, R507a).
• 2015: The EU decides to reduce the use of HCF refrigerants gradually.
• Also 2015: The era of natural and HFO refrigerants begins.

The purpose of the decisions made by the EU in 2015 was to find refrigerants with the lowest GWP values possible. Natural refrigerants are usually considered to include ammonia (0), carbon dioxide (1) and hydrocarbons such as propane (3), butane (4) and ethane (6). Synthetic HFO refrigerants include, for example, R-1234yf (1), R-1233zd (4), R-1134ze (1) and R-1366mzz (2). The figures in brackets are the GWP (Global Warming Potential) values of the substances.

However, when refrigerants are examined, it is not sufficient to take only the GWP value into consideration. When selecting refrigerants, the emissions generated during their production and the long-term decomposition of refrigerants leaking from systems should also be taken into account. In addition, the user should consider whether the refrigerant will be available throughout the useful life of the equipment and how its price will change over the years.

In terms of the environment, the most important aspect is the decomposition of refrigerants and their breakdown products leaking into the environment. According to studies, trifluoroacetic acid (TFA), which is one of the breakdown products of fluorinated refrigerants (HFO), has been found, to an increasing extent, in rain and drinking water.

According to a statement issued by the German Environment Agency (UBA) in May 2022, using low GWP natural refrigerants in heat pump and refrigeration systems is the best way to reduce TFA in our environment and there by prevent this harmful substance from affecting people and animals through the soil. The EU has already started to analyse whether some of the HFOs should be listed as PFAS (forever chemicals), which are extremely harmful. It is hoped that these observations will accelerate the transition towards natural refrigerants, and that this change can be implemented among manufacturers and users more rapidly than previous changes. This would ensure that the energy-saving principle of heat pumps is not built on technical solutions that will burden the environment with new emissions.

I hope that those purchasing heat pumps will look far into the future and make decisions that will withstand critical examination for decades to come.