Heat pumps are seen as a key technology in decarbonization since they do not emit carbon dioxide (CO2) when generating heat or cold from renewable sources while contributing to increasing the energy efficiency of buildings. They are able to provide high-performance heating and cooling by using electricity, thereby avoiding the emissions from gas, oil and coal boilers. Specifically, heat pumps have the potential to reduce global CO2 emissions by at least 500 million tonnes by 2030, equivalent to the annual CO2 emissions of all the cars in Europe today.
The high performance of heat pumps is derived from the fact that they deliver a thermal output higher than the electric input required. Developments have led to a great increase of thermal output over time. For instance, the efficiency of air-water heat pumps has increased by more than 70% since the early 1990s2, meaning that CO2 emissions have been reduced further.
Clearly, the reduction of CO2 emissions from heat pumps compared to gas boilers will become more pronounced as the share of renewables in the energy mix increases. To give a rough idea, currently renewables make up about 22% of the energy mix in Europe3. Key policies announced recently, such as REPowerEU in the European Union (EU), the Inflation Reduction Act in the United States (US) and China’s 14th Five-Year Plan for Renewable Energy, will give an additional boost to renewable electricity deployment in the coming years. Moreover, heat pumps are regarded as a crucial tool in achieving independence from foreign sources of fossil fuels.
Refrigerants: a key challenge for heat pumps
With heat pumps powered by renewable energy, the refrigerant will remain the only source of CO2 emissions during their operating life. The most common refrigerant in heat pumps today, R-410A, has a Global Warming Potential (GWP) of 2088, which means that its impact on the greenhouse effect is 2088 greater than the impact of CO2. The alternative refrigerant widely used in new heat pumps, R-32, has a lower GWP: 675. The use of natural refrigerants, such as R-290 (propane) or R-744 (CO2), drastically reduces CO2 emissions since they have a negligible GWP. Other very low GWP alternatives, such as R-1234yf or R-1234ze(E), also help reduce greenhouse emissions but could be subject to potential PFAS restrictions in the future.
Under ideal circumstances, a heat pump powered by energy only from renewable sources and using a natural refrigerant would be a near-zero emissions technology during its operating life. As worldwide refrigerant regulations are phasing out the use of fluorinated refrigerants, in line with Kigali Amendment to the Montreal Protocol, technological developments are making possible the use of natural refrigerants in heat pumps, extending their use rapidly. It is essential that refrigerant policies and technological developments go hand in hand so that regulations do not become a barrier to the spread of heat pumps.
Why are actions on heat pumps essential?
Regardless of the refrigerant used, the transition to wider use of heat pumps has a long way to go. Globally, heat pumps still meet only around 10% of the global heating requirements of buildings1. However, the supply of heat pumps would need to almost triple by 2030 in order to cover at least 20% of global heating needs and meet the goal of net zero emissions by 20501, which will be indispensable in achieving the aims of the Paris Agreement: limiting global warming to below 2°C and attempting to keep it to 1.5°C.
Actions to reduce emissions from heating and cooling systems are essential, given their enormous contribution to total electricity usage. For instance, about 50% of all energy consumed in the EU is used for heating and cooling4. This is not surprising when the division of power in our houses is considered: it is estimated that around 80% of the final energy consumption of the residential sector is used for room and water heating.
Many policies and incentives directly or indirectly promote the use of heat pumps in different countries. These strategies, along with other factors, such as the increasing use of renewable sources for electricity, have contributed to the expansion of the heat pump market. Global sales of heat pumps increased by 11% in 2022, with record growth in Europe and in the US1.
In the EU, three million heat pumps were installed in 2022, reaching a total of around 20 million units, as highlighted by the European Heat Pumps Association (EHPA) in its last annual report. Curiously, the number of heat pumps grew on average by 11% a year from 2011 to 2020 yet sales boomed during 2022, recording an increase of 39%. The strongest relative growth in 2022 was achieved in Belgium, Poland, and the Czech Republic. Reversible air-water and air-water systems contributed most to the overall gains.
In US, heat pumps surpassed gas boiler shipments for the first time in 2020 and the trend was maintained in 2022, reaching 53%. The market is dominated by air source heat pumps, whereas heat pump water heaters, water loop heat pumps, and ground source heat pumps made up a little over 7% of heat pump sales in 2022.
Conclusion
The popularity of heat pumps has grown in the last years, as they are the enabling application for the electrification of space and water heating systems, thus avoiding CO2 emissions from burning fuel fossils. However, a number of challenges will have to be overcome if a timely transition from fossil fuel boilers to heat pumps as a heating source is to be successfully achieved. Policies and incentives to promote the use of heat pumps, together with technological development, are essential to achieve the needed results.
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Source: “Heat pumps: how much is enough?” carel.com
