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Electric Vehicle Manufacturers ‘Highly Likely’ to Adopt Natural Refrigerant-Based AC, Says Consulting Firm

According to Ducker Carlisle, OEMs will opt for CO2 or R290 instead of widely-used HFO 1234yf in mobile air-conditioning.

Over the next five years, manufacturers of plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs) are “highly likely” to opt for natural refrigerants like CO2 (R744) or propane (R290) in place of HFO 1234yf in mobile air-conditioning (MAC) systems, according to a white paper from consulting firm Ducker Carlisle.

“Due to stricter environmental legislation across industries, many OEMs and thermal management suppliers anticipate that the EU will implement a regulation banning R1234yf by 2030,” explained the company, noting that the HFO is used in the majority of today’s PHEVs and EVs.

As a PFAS (per- and polyfluoroalkyl substance), R1234yf could be banned under the EU’s chemicals REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation if the Universal Restriction Proposal – officially known as the Annex XV Restriction Report – is approved by the European Chemical Agency.

“If a ban were to be voted, OEMs would have to shift to either CO2 or propane – provided the safety concern related to the flammability of propane has been addressed,” the consulting firm said.

“Due to stricter environmental legislation across industries, many OEMs and thermal management suppliers anticipate that the EU will implement a regulation banning R1234yf by 2030. If a ban were to be voted, OEMs would have to shift to either CO2 or propane.”

Ducker Carlisle

The transition to natural refrigerants will also be driven by government subsidies that favor the use of low-GWP refrigerants in thermal systems, it added.

Beyond environmental regulations, vehicle performance is also a driving factor.

As manufacturers increase their production of electric vehicles, many are focusing more on heat pump design concepts and refrigerant selection due to the impact thermal management systems have on vehicle battery range and lifespan. In electric buses, for example, R744-based heat pumps have been found to outperform electric heaters, boosting range by more than 32%.

According to Nina Piesch, a Research Assistant from the Norwegian University of Science and Technology, CO2 heat pumps boast a higher efficiency in EVs because of their increased suction vapor density. They also eliminate the need for an auxiliary heater, which enhances overall efficiency.

While all OEMs are looking at heat pump design and refrigerant selection, it is a particular priority for premium manufacturers as their customers demand a higher level of comfort and performance, explained Ducker Carlisle.

NatRefs in cars

According to Ducker Carlisle, a growing number of automakers are looking into CO2 heat pumps following the announcement that Volkswagen had chosen the technology for its modular electric drive matrix (MEB) platform. Volkswagen has said its goal is to use R744 heat pumps in all of its EVs by 2030.

Volkswagen’s MEB platform underpins several EVs in the group’s portfolio, including the Audi Q4 e-tron, which first began offering CO2 heat pumps as an option in 2021.

“When Volkswagen adopts a strategy, others are likely to follow,” a renowned international thermal management system provider told Ducker Carlisle. “We are currently receiving numerous proposal requests for R744 heat pumps, suggesting that many OEMs seem to be considering a CO2 heat pump.”

Volkswagen’s new ID.5 electric SUV coupe uses a CO2 heat pump.
Volkswagen’s ID.5 electric SUV coupe uses a CO2 heat pump. (Source: Volkswagen)

However, it is unclear whether other OEMs will follow suit and commit to CO2, continue with R1234yf or opt for other solutions like propane. This decision depends on multiple factors, including regulations, subsidies, vehicle type and size, safety concerns and brand positioning, explained Ducker Carlisle.

While propane is a highly efficient and inexpensive refrigerant, there are significant safety concerns due to its flammability, explained Stefan Schäfer, Business Development Manager at Burger Group. However, with the right technology and design, propane can also be a safe refrigerant, he added, noting that systems must be “designed as a closed unit with permanently sealed connections.”

Despite regulators like the U.S. Environmental Protection Agency (EPA) advising against the use of propane in MAC applications, the automotive industry has not ruled it out.

In June 2023, German technology company ZF presented TherMas, a new electric-drive system with a propane heat pump. With one circuit dedicated to the passenger compartment and two additional and separate circuits used for the thermal management of the power electronics and the e-drive, the heat pump doubles the cooling capacity compared to current refrigerants, while safety is ensured through a hermetically sealed system.

To date, no carmaker has announced a plan to adopt R290 for MAC systems.

“Due to the flammability of propane, it is expected that CO2 heat pumps will hold a higher market share for passenger cars,” said Ducker Carlisle.

NatRefs in public transport

With significant heating and cooling demands, buses are more likely to adopt CO2 and R290 in their HVAC systems than passenger cars, explained Ducker Carlisle.

In Germany, CO2 has become the refrigerant of choice for heat pumps in electric buses, with numerous cities opting for the technology in their bus fleets. In fact, as of 2021, more than 60% of Germany’s electric buses used R744 heat pump systems from manufacturer Konvekta.

This trend is extending across Europe.

“Since 2018, we have installed over 3,500 CO2 air/water heat pumps in European buses and anticipate another 2,500 new units this year,” said Karsten Mundt, Sales Director International at Konvekta. “Additionally, the increasing demand for CO2 applications in the automotive sector will drive innovation, lower component prices and ensure safety as well as efficiency for operators.”

Konvekta heat pump-equipped electric bus E bus
Konvekta’s CO2-based heat pumps are used in electric buses across Europe. (Source: Konvekta)

The adoption of propane in buses is also on the rise, with the ability to overcome safety concerns by installing heat pumps on bus roofs rather than alongside engines – as is the case with cars.

“Propane started to be used in buses a few years ago, and use cases are expected to strongly grow in the coming years due to its excellent thermal performance,” explained the unnamed thermal management system provider.

Natural refrigerants are also increasingly being adopted in train HVAC systems, with researchers finding that a CO2-based air conditioner can offer a 14% increase in cooling capacity and a 16% increase in COP over a system using HFC blend R407C.

German train operator Deutsche Bahn has committed to only using natural refrigerant-based heating and cooling systems in its trains from 2020. The company already has a passenger train using propane-based air-conditioning units (alongside “state-of-the-art” electric heaters) and has been testing CO2 heat pumps for both heating and cooling.

Showcasing MAC innovation

In recognition of the rapidly changing landscape in the MAC sector, ATMOsphere, publisher of NaturalRefrigerants.com, will host its first MAC and heat pump summit, ATMO MAC Summit 2024 × TU Berlin, in Berlin September 12–13.

The two-day event is organized in partnership with Technische Universität Berlin (TU Berlin)’s Department of Heat Transfer and Conversion and will be hosted at the university’s campus.

According to ATMOsphere, the conference will “offer a unique opportunity to engage and exchange insights with industry professionals.” Participants will include manufacturers from across the transport sector, suppliers and policymakers, as well as academics and R&D experts.

The event program will feature presentations and case studies on natural refrigerant-based air-conditioning and heat pump technologies for mobile applications, with a focus on CO2 and propane.

Sessions will cover a range of topics, including research, market and technology trends, electric vehicles, refrigerant charge reduction strategies and system controls and safety. Two panel discussions – one on policy developments and one on OEM experiences – are scheduled for the second day of the summit.

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