R744 (CO2) vs R290 (propane) — picking the right natural refrigerant for commercial refrigeration
By DigiEntropy Engineering · 2026-02-15 · 8 min read
Both R744 and R290 survive every regulatory threat on the horizon — F-Gas, PFAS, the lot. Both are commercially mature. So which one for your project? A frank comparison from someone who's watched the catalog data accumulate.
About this post — Authored by an AI assistant using DigiEntropy's polynomial corpus, the universal compressor predictor, and the project's chart-generation tooling. Charts are produced by Python scripts that read the same database the live site queries; tables and formulas are pulled from the same engineering modules. Findings reflect the project's current dataset and methodology — send corrections or deeper questions to admin@digientropy.com.
Both R744 (CO2) and R290 (propane) survive every regulatory threat on the horizon — F-Gas Regulation 2024/573 (both GWP under the 150 threshold), the proposed PFAS restriction (neither degrades to PFAS-class compounds), Montreal Protocol (zero ozone depletion potential). Both are commercially mature: CO2 transcritical has dominated European supermarket refrigeration for a decade, propane has been the default for low-charge plug-in cabinets just as long.
So if you're specifying a new commercial refrigeration system in 2025+ and you've ruled out the HFCs and HFC/HFO blends on F-Gas + PFAS grounds, which natural refrigerant?
The honest answer is it depends on charge size, climate, and operating envelope. This post walks through the decision.
1 and 3 - GWP of R744 and R290 - both under the 150 threshold
Both R744 (CO2) and R290 (propane) survive every regulatory threat on the horizon: F-Gas Regulation 2024/573 (both GWP under the 150 threshold), the proposed PFAS restriction, Montreal Protocol.
5-50 kW - where the choice matters - the capacity ranges overlap
The capacity ranges overlap in the 5-50 kW window, and that's where the decision actually matters. Below 5 kW, R290 wins easily. Above 100 kW, R744 wins.
150 g - R290 charge cap per circuit - direct expansion, occupied space
R290 is capped at 150 g per circuit for direct-expansion systems serving an occupied space. R744 has no such limit.
100 bar - R744 transcritical pressure - R290 runs at 25 bar
A typical R744 transcritical system runs at 80-100 bar on the high side. R290 runs at 25 bar, the same component class as the HFC system you're replacing.
15-25% - R290 annual-energy advantage - above 30°C ambient
Above 30°C ambient, R290 outperforms R744 transcritical by 15-25% on annual energy in typical commercial refrigeration duty.
€32,000 - R290 install, the 18 kW store - R744 rack: €55,000
- R290 distributed plug-ins for cabinets + R290 chiller for cold room: €32,000 install, 7500 kWh/year.
- R744 transcritical centralised rack: €55,000 install, 9000 kWh/year.
The high-level picture
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