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. The high-level picture R744 (CO2) R290 (Propane) --------- GWP 1 3 Safety class A1 (non-flammable, non-toxic) A3 (highly flammable) ODP 0 0 PFAS risk None None Typical capacity range 5-5000+ kW 0.5-50 kW System pressure High (transcritical 100 bar) Moderate (25 bar) Charge limits (EN 378) None (A1) Strict — 150 g for direct expansion in occupied spaces, up to 5 kg with indirect / outdoor systems Best at Supermarkets, large food storage, transcritical retrofit Plug-in cabinets, small commercial, heat pumps 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. The case for R744 Three reasons CO2 dominates large commercial refrigeration: 1. No charge limit EN 378 imposes strict charge limits on flammable refrigerants in occupied spaces. R290 is capped at 150 g per circuit for direct-expansion systems serving an occupied space — that's a few kW of capacity. Above that you need either indirect systems (secondary loop) or outdoor placement. R744 has no such limit. You can fill a centralised supermarket rack with hundreds of kg of CO2 without any code restriction. This is why every new European supermarket since 2018 is CO2 transcritical. 2. Mature ecosystem Bitzer ECOLINE CO2, Dorin CD series, Frascold Q-series transcritical, Bock HGX CO2, Carlyle, Copeland — the compressor ecosystem…