While heat pumps are “increasingly recognised as a critical technology for heat decarbonisation” and “energy security”, this technology meets only “about ten percent of the global heating need in buildings”. As the International Energy Agency’s heat pumps tracking report continues, this is “below the deployment level required to get on track with the Net Zero Emissions by 2050 Scenario”; that requires a stock of 600 million global heat pumps by 2030, versus 190 million in 2021.
This involves “policy support and technical innovation” to “reduce upfront purchase and installation costs, remove market barriers to complex renovations, improve energy performance and durability, and explore the potential of heat pumps as an enabler of power system integration and flexibility”.
The concept of heat pumps is not new – arguably, the first one was built in the 1850s. Their special attraction in the twenty-first century, is the ability to draw heat from a source (e.g., the air or ground) to heat air and water in a building without burning fossil fuels. Hence, with a green source of electricity (e.g., from wind, solar, hydro, nuclear) to power a heat pump, it’s possible to reduce hydrocarbon use, to supply a common, human need.
While gas and oil-powered boilers are well-established and popular means of heating homes and the workplace, increasing environmental and health concerns over the past few decades, as well as more recent, alarming increases in gas and electricity costs, have caused many to consider other methods.
Ostensibly, heat pumps are a possible solution, as they use a relatively small amount of energy to transport heat from a source at a low temperature to provide warmth. For example, they may receive waste heat from an industrial process, or from the air or ground to heat air and/or water in a building. However, heat pumps are still in the minority of solutions used for this.
They are more commonly adopted in other applications, such as tumble driers or air conditioning systems in vehicles, where a heat pump is employed to re-use heat generated by the device, rather than expelling it into the atmosphere and consuming further energy to manage air temperature.
Barriers to adoption
To understand the barriers to adoption of heat pumps for domestic air and water heating, we contacted William Spain of Revolutionary Concepts, a consultant mechanical engineer.
Spain highlighted the significant split in heating solutions, in most markets, between new build installation – where heat pumps are more beneficial – and retrofit installation in older housing stock. Heat pumps have a lower power output than gas boilers, so established housing with poor insulation (e.g., those in the UK) may not be suited to heat pumps, now.
Additionally, current designs of air source and ground source heat pumps are prone to poor efficiency in cold weather, which limits where they can deliver sufficient heat output.
A shortage of electricity to power heat pumps may be a major barrier to their adoption since, in the UK at least, it is not clear if the local electrical grid could meet the demand for high-density deployment of heat pumps.
While total life costs for gas boilers are often lower than just the installation costs for the more complex heat pumps, the latter’s added complexity may also make them inherently more unreliable. Historically at least, heat pumps just do not perform as advertised.
Installation disruption is also something people want to avoid in existing housing – for example, the requirement to change piping and radiators when incorporating a heat pump system. Heat pumps can also lead to low radiator temperatures, which may mean an immersion heater is still required.
Before heat pumps can become a significant contributor to reducing fossil fuel use, there are technical challenges to overcome.
Global patent activity
Research, development, and patent applications should be the obvious consequence of the need to solve current technical challenges with heat pumps.
As shown in Figure 1, patent filing numbers for heat pump-related technology are relatively constant, except in Japan where they have significantly dropped. This may indicate a switch to a different solution, or technologies may have already attained an acceptable level of performance.
Figure 1: Twenty-year trend: priority filings – most active jurisdictions – heat pump technology
However, as Figure 2 shows, the overall number of priority filings relating to heat pumps has dropped, and then plateaued, over recent years.
Figure 2: Twenty-year trend: global priority filings – heat pump technology
As shown in Figure 3 below, there is no clear pattern to applicants’ interest in securing intellectual property (IP) in this area.
Automotive industry applicants (e.g., Toyota, Hanon and Mitsubishi) have filed patents related to heat pumps, along with providers of heat and air solutions (e.g., LG, Daikin and Stiebel), with varying levels of interest and much year-on-year variation. However, what the data shows is an enduring interest in the technology.
Figure 3: Filing activity 2008-2020: top ten patent applicants – heat pump technology
Atechnology field that has seen a recent increase in filings is the use of heat pumps in transportation, as shown in Figure 4.
Figure 4: Twenty year trend: global priority filings – heat pump technology in transportation
One reason for this rise may be attributed to the rise in electric vehicles. EVs do not produce sufficient waste heat to adequately heat the interior of a vehicle (compared to traditional internal combustion engine vehicles) and so car manufacturers are turning to alternative heating solutions. In addition, heat pumps can be used during cold months to improve the efficiency of electric vehicle batteries by heating them to a target temperature.
As shown in Figure 5, car manufacturers are heavily involved in this field with Hyundai, Ford and Toyota all making filings in recent years.
Figure 5: Filing activity 2007 – 2020: top ten patent applicants – heat pump technology in transportation
Likewise for some system-related patent applications, patent filings are increasing (e.g., key applicants for district heating are EON and the Korea District heating corporation).
Heat pumps are, of course, made up of several components and operated by control systems which should, theoretically, influence technical developments and patent applications. However, for common heat pump elements such as expansion valves, heat exchangers, control systems, antifreeze solutions and defrosting management, and system integration, patent filings peaked in 2011, declined, and have now plateaued. Filings for other key parts, such as condenser coils and evaporator coils, show no significant increase in patent filings.
Conventional systems incorporating heat pumps (such as tumble driers) show fairly constant patent filings, perhaps suggesting ongoing perceived value in making these more efficient.
Implications for innovation and future patent filings
Spain suggests that the challenge for innovators and future patent holders may lie in achieving incremental improvements in component design, to make them more reliable, or a paradigm shift that provides a boost in efficiency and reduces installation costs. Other potential areas for innovation and patent applications include:
- Increasing combined use of energy systems involving renewable energy sources, such as solar or solar thermal
- Developing smart management systems that ensure heat pumps in a given location are not all operational simultaneously – addressing concerns about the effect of increased electricity consumption on the local electrical grid
- Systems which employ heat pumps alongside sources with higher thermal energy (e.g., from heat stored rather than “dumped” from other processes, devices or generated by solar thermal) to produce very high efficiency output
- Combining heat pump technology for space heating with, e.g., immersion heaters, to heat both air and water
- Innovation in alternatives created by legislation focused on more environmentally friendly refrigerants
- System management innovation driven by the need to address issues caused by the lower operating temperatures of efficient heat pump systems (e.g., icing, high temperature heat pumps and legionella regulations)
The patent data reveals that heat pumps remain relevant technology in different applications, and feature as part of a wide range of applications. Any development that increases their suitability for heating air and water would be a very valuable contribution to reducing reliance on fossil fuels.
There is also a keen economic interest in continuing to develop their components and the systems they operate in.
Paul Beynon Senior Associate
Adam Tindall Partner