In automotive thermal management, the reason refrigerants such as R290 (propane) have returned to the spotlight is not singular. Environmental regulations are tightening, electric vehicles are becoming increasingly sensitive to heat pump efficiency, PFAS-related replacement paths are being evaluated more actively, and OEMs together with Tier 1 suppliers are moving thermal management beyond an air-conditioning subsystem toward a platform that influences range, charging performance, comfort, and safety at the same time. R290 sits precisely at the intersection of these variables. It offers a very low global warming potential, its thermodynamic performance continues to attract attention, and it has already appeared in publicly presented EV thermal management solutions from several major automotive suppliers. At the same time, it is also a highly flammable refrigerant, which raises the threshold for safety design significantly. This is what makes its adoption in automotive applications both attractive and clearly challenging.[1][3][4][5]

The Link Between R290 and Automotive Thermal Management Begins with Its Role as a Heat Pump / Refrigeration Refrigerant

In automotive thermal management, R290 is not primarily used as a coolant in the conventional liquid circuit, nor is it simply an auxiliary material. Based on currently available public materials, the main direction of application is concentrated in its use as a refrigerant / heat pump working fluid in EV thermal management systems. In other words, it enters the cabin air-conditioning loop and heat pump heating and cooling loop, while also coupling with the thermal control requirements of the battery, electric drive, and power electronics. ZF’s publicly released TherMaS is defined as a propane-based thermal management system for the EV market, providing at least 10 kW of both cooling and heating capacity with an operating ambient range from -25°C to +35°C. Bosch Mobility’s public heat pump unit also explicitly states that its solution integrates a propane refrigerant. MAHLE, in its CES 2025 materials, further indicated that its Thermal Management Module is compatible with PFAS-free R290 refrigerant and directly linked the solution to battery fast charging, range performance, and battery life management.[3][4][5]

This matters because it shows that R290 has moved beyond being a theoretically viable substitute refrigerant and has entered the candidate list for vehicle-level thermal management architectures. Once suppliers begin naming R290 in thermal management modules aimed at mass-production pathways, the market conversation no longer remains confined to the laboratory. It moves into the stages of platform development, regulatory evaluation, supply-chain preparation, and safety validation.[3][5]

R290 Is Entering Automotive Thermal Management Primarily Because Regulations and Environmental Targets Are Pushing the Path Forward

From a regulatory perspective, the direction for mobile air-conditioning systems in Europe is already clear. Since January 1, 2017, all new vehicles placed on the EU market must use fluorinated greenhouse gases in mobile air-conditioning systems with a GWP below 150. The European Commission’s official materials also list R1234yf, R744, and R290 as climate-friendly alternatives for mobile air conditioning. For automakers, this means refrigerant selection is no longer merely a matter of legacy practice or cost preference. It is increasingly shaped by regulatory thresholds, environmental objectives, and long-term technology direction.[1]

Illustration of the R290 heat pump loop within EV thermal management systems

Within this logic, R290’s environmental profile is highly attractive. The European Commission identifies it as an ultra-low-GWP refrigerant, and ASHRAE includes R290 within its official refrigerant designation system. At the same time, the industry is increasingly discussing PFAS replacement, and MAHLE directly links R290 to a PFAS-free path in its public materials. For EV thermal management, a low-GWP, non-fluorinated route naturally carries both policy and brand narrative advantages.[1][2][5]

Even more noteworthy is the fact that, in 2026, India’s Ministry of Environment, Forest and Climate Change launched a dedicated research tender on the use of low-GWP mobile air-conditioning systems in electric vehicles. The research scope covers passenger vehicles, trucks, and transport refrigeration vehicles, and calls for systematic evaluation of thermal performance, safety classification, suitability for local climate, cost, supply-chain maturity, and service-network readiness. The fact that a national government department has formally placed low-GWP automotive refrigerant routes onto a research agenda already indicates that this is not a marginal topic.[6]

Beyond Low GWP, R290 Is Also Drawing Attention Because It Directly Relates to EV Efficiency, Range, and Heat Pump Performance

Environmental positioning alone would not be enough for R290 to generate this level of attention in the automotive sector. The reason it has entered the field of view of OEMs and Tier 1 suppliers is closely tied to EV thermal management efficiency. ZF stated publicly in 2025 that TherMaS can improve range by up to 10% through optimized heat utilization and higher winter efficiency, and even up to 30% under extreme conditions. Bosch defines its propane heat pump solution as a path to improving driving comfort while minimizing range impact. MAHLE likewise positions its next-generation thermal management module around enhancing range, supporting high-power charging, and improving battery temperature control.[3][4][5]

Academic research aligns closely with these industrial developments. A 2025 paper published in Case Studies in Thermal Engineering reported that propane-based heat pumps in EVs can improve both heating and cooling performance and showed better efficiency and heat output than R1234yf in tests from -35°C to 0°C, with range gains of up to about 5% in cold environments. A 2022 study in Energy Reports found that an R290-based EV heat pump air-conditioning system performed well in both high-temperature cooling and low-temperature heating conditions. A 2024 experimental study in Science China Technological Sciences also showed that an R290 vapor-injection heat pump system developed for EVs could operate across ambient conditions from -30°C to 0°C, with systematic analysis of charge amount, injection pressure, and cabin temperature parameters.[7][8][9]

This means that R290 is being taken seriously in automotive discussions not merely as a replacement for an older refrigerant, but because it could influence the overall performance of the vehicle thermal management system: cooling, heating, range, winter operation, temperature control during charging, as well as system size and integration level.[3][5][7][8][9]

Heat pump loop illustration of R290 within an EV thermal management system
The heat pump loop of R290 within an EV thermal management system and its coupling relationship with the cabin, battery, and electric drive.

The Challenges Are Just as Clear: R290 Is an A3 Refrigerant, and Its Flammability Raises the Entry Barrier Far Above Conventional Substitution Paths

The biggest point of debate surrounding R290 is also very clear. ASHRAE formally classifies R290 as an A3 refrigerant, meaning low toxicity but high flammability. The UK F-Gas Register technical brief likewise states that R290 is a highly flammable refrigerant. In the automotive sector, the significance of this characteristic is amplified. Vehicle operating conditions involve vibration, collision scenarios, confined spaces, dense electrical equipment, multiple heat sources, strict occupant safety requirements, and complex aftersales repair environments. As a result, OEM tolerance for A3 refrigerants will always depend on one critical prerequisite: system-level safety must be controllable.[2][10]

Academic literature describes these risks in considerable detail. A 2020 study published in International Journal of Refrigeration analyzed leakage and concentration distribution of R290 in automotive air-conditioning systems and concluded that evaporator leakage represents a high-risk operating condition, because refrigerant may enter the passenger cabin and form dangerous local concentrations. Related research in 2023 further indicated that condenser leakage in EV underhood scenarios can produce more hazardous flammable-zone distributions, with leakage aperture and charge amount both significantly affecting risk level. Additional experimental work on leakage and combustion characteristics in EV heat pump systems also shows that R290 may introduce fire or explosion risk under potential leak events, which remains one of the most important safety constraints on broader adoption.[11]

This is precisely why recent research and public industry materials frequently include keywords such as “secondary loop,” “indirect heat pump,” “safety regulations,” and “charge reduction.” A 2025 study on single-loop and dual-loop indirect propane heat pumps explicitly stated that, when propane is used, single-loop or dual-loop indirect systems are needed in order to comply with safety regulations. A 2025 review in The Innovation Energy also noted that, because of flammability constraints, R290 often requires secondary-loop architectures.[12][13]

Final Assessment: The Opportunity for R290 in Automotive Applications Has Already Emerged, but the Pace of Commercialization Depends on Whether Efficiency Gains and Safety Closure Can Be Achieved Together

Taken together, public materials and recent research show that R290 has already entered a substantial phase of technical evaluation and prototype-level demonstration in automotive thermal management, with the main focus on EV heat pumps, cabin air-conditioning systems, and integrated thermal management modules coupled with the battery and electric drive. It is gaining attention primarily because low GWP and heat pump efficiency improvement form a compelling combination. Its progress remains cautious primarily because A3 flammability significantly raises the threshold for system design, safety validation, and regulatory justification.[1][2][3][4][5]

So, the most accurate answer to the question of why highly flammable R290 is still entering automotive thermal management systems is this: it offers efficiency and environmental value that OEMs are willing to evaluate seriously, while at the same time requiring the industry to deliver more mature safety engineering solutions. As long as both of these lines continue to advance, the presence of R290 in automotive thermal management is likely to keep growing.[7][8][9][12][13]

References

  1. European Commission. Mobile air-conditioning systems (MACs).
  2. ASHRAE. ASHRAE Refrigerant Designations.
  3. ZF. Comfortable temperature for electric cars: New ZF thermal management system increases range by up to 10 percent.
  4. Bosch Mobility. Heat pump unit.
  5. MAHLE. CES 2025: MAHLE on Display with Electrification as the Focus.
  6. Ministry of Environment, Forest and Climate Change, India. Study on use of Low GWP Mobile Air-Conditioning (MAC) in India’s electric vehicles.
  7. Khader, S. et al. 2025. Electric vehicle heat pump system operated with R290... Case Studies in Thermal Engineering.
  8. Huang, Y. et al. 2022. Research on the electric vehicle heat pump air conditioning system with R290 refrigerant. Energy Reports.
  9. Yang, Y.C. et al. 2024. Performance analysis of an R290 vapor-injection heat pump system for electric vehicles. Science China Technological Sciences.
  10. UK F-Gas Register. Flammable refrigerants in air conditioning and heat pump systems.
  11. Li, K. et al. 2020. Experimental investigation on combustion characteristics of R290/R1234yf...
  12. Kwon, S. et al. 2025. Single- and dual-loop indirect heat pumps with propane...
  13. Future development trends in new energy vehicle thermal management system... The Innovation Energy, 2025.