Figure 1. Heat pump

Heat pumps are the most energy-efficient way of controlling indoor temperature. Despite being nearly a century and a half old, this technology is experiencing a resurgence in a novel manner. Transitioning to heat pumps fueled by renewable energy sources can lead to substantial reductions in emissions for households, offices, and even industrial plants.

The details of how heat pumps work are shown in Figure. 1. To heat your home in the winter, an electricity-powered fan on the heat pump draws in air from outside and passes over an evaporator coil containing the refrigerant. Heat from the outdoor air causes the refrigerant to absorb heat and evaporate, turning it into a vapor. The vapor is then compressed by a compressor, which increases its pressure. This high-pressure, high-temperature vapor is then circulated into the home, releasing heat as it condenses into a liquid in the condenser coil. The liquid refrigerant then passes through an expansion valve, where its pressure and temperature are reduced, preparing it to repeat the process. In the summer, the process is reversed, and the principle is identical to AC.

The main thing you need to take away from this is that heat pumps do not actually create heat; they simply move it. Because of this, they are both effective and durable. During the summer, heat pumps remove excess heat from indoor spaces, making them a cost-effective alternative to central air conditioning.

Global sales of heat pumps increased 11% in 2022 [1], the second consecutive year of double-digit increases, but the rate may have slowed in 2023. Europe is the place to see the most notable transformation, with 40% growth in heat pump installations through 2022, primarily driven by the energy crisis arising from the Russia-Ukraine war and by efforts to use fossil fuels.

Asia is not out of the game. With China leading the way in heat pump installations globally, China and Japan account for more than half of all new patents filed on heat pump technology since 2010 [2]. → New methods are allowing heat pumps to achieve higher temperatures, which could enable the technology to help clean up industrial production [3] by providing energy to create steam used in food processing and paper production.

Collectively, heat pumps have the capacity to slash global emissions by 500 million tons by 2030— equivalent to eliminating all cars in Europe [4]. Achieving this requires the installation of approximately 600 million heat pumps by the end of the decade [5]. Nonetheless, significant challenges lie ahead, including scaling up production to meet increasing demand and ensuring the resilience of the grid to support such technologies, emphasizing the imperative of addressing climate change. Nevertheless, all indications suggest that heat pumps are entering a period of peak performance.