ShareNatural refrigerants power the transition to climate-friendly transport refrigeration
Refrigerated transport is essential to global food and pharmaceutical supply chains – but it’s also a hidden source of greenhouse gas emissions. As climate targets tighten and refrigerants face regulatory phase-outs, the sector stands at a crossroads. Can natural refrigerants deliver the performance, safety, and sustainability needed to future-proof cold logistics?
A comprehensive review published in the International Journal of Refrigeration, explores how natural working fluids (NWFs) such as carbon dioxide (CO₂), ammonia, and hydrocarbons are reshaping the future of transport refrigeration. The study, led by Silvia Minetto, President of the IIR’s Commission D2 on Transport Refrigeration, outlines both current applications and emerging innovations that support the transition to low-emission, energy-efficient cooling systems across road, rail, sea, and air transport.
Transport refrigeration systems face unique challenges – including space constraints, harsh environmental conditions, and high refrigerant leakage rates. According to the study, leakage rates in refrigerated trucks can reach up to 165% of the initial charge over a 10-year lifespan, contributing significantly to greenhouse gas emissions. The adoption of NWFs offers a path to drastically reduce these emissions while improving system reliability and safety.
CO₂: A Safe and Scalable Solution
Carbon dioxide is gaining traction as a non-toxic, non-flammable refrigerant suitable for a wide range of transport applications. The review highlights successful field trials of CO₂-based systems in trailers, intermodal containers, and fishing vessels, with innovations such as ejector cycles and multi-temperature configurations improving performance even under extreme ambient conditions.
In fishing vessels, CO₂ systems have demonstrated up to 70% performance improvement in warm climates compared to traditional systems. The technology also enables heat recovery, which can be used for onboard processing, such as fish oil production.
Ammonia and Hydrocarbons: Efficient but Regulation-Dependent
Ammonia is already widely used in marine refrigeration, often in cascade systems with CO₂ to achieve ultra-low temperatures. Hydrocarbons like propane (R290) offer high efficiency and low environmental impact, but their flammability requires robust safety standards and risk assessments. Field tests in South Africa showed 25% higher COP and significant reductions in fuel consumption and emissions when replacing R404A with R290 in refrigerated trucks.
Cryogenic and Hybrid Systems
The review also discusses thermal energy storage (TES) systems using liquefied CO₂ or nitrogen, which are gaining popularity in urban delivery and air cargo. Hybrid systems combining cryogenics with vapour compression cycles are emerging as promising solutions, especially when integrated with electric or solar-powered vehicles.
Policy and Market Outlook
The paper emphasises the impact of EU F-gas regulations, the Kigali Amendment, and upcoming PFAS restrictions, which are accelerating the shift away from synthetic refrigerants. Minetto calls for standardisation efforts, particularly for flammable refrigerants, to support manufacturers in deploying safe and efficient NWF-based systems.
The complete study is available in open access in FRIDOC.