Cold chain logistics is carbon-intensive. Refrigeration, transport, and packaging materials all carry embodied carbon that rarely appears on a sustainability dashboard but contributes meaningfully to a business’s total emissions profile. As Australia moves toward its 2030 and 2050 emissions targets, cold chain operators face increasing pressure from corporate procurement teams, ESG reporting requirements, and customers who want to know what their delivery actually costs the planet.
The most loaded question in this conversation is the one that seems simplest: dry ice or gel packs? The answer is not straightforward, and anyone who gives you one without caveats is oversimplifying the physics and the lifecycle accounting.
Understanding Embodied Carbon in Cold Chain Packaging
Embodied carbon — the total greenhouse gas emissions associated with a material across its entire lifecycle — is measured in kg CO₂e (carbon dioxide equivalent). For cold chain packaging, the relevant lifecycle stages are:
- Raw material extraction and processing
- Manufacturing
- Transport to point of use
- Use phase (including refrigeration energy)
- End-of-life disposal or recycling
Most cold chain sustainability conversations focus on the use phase — the energy consumed by refrigeration equipment. This is important, but for passive packaging solutions (insulated mailers, gel packs, dry ice), the manufacturing and end-of-life stages often dominate the carbon profile.
Dry Ice: The Carbon Paradox
Dry ice is solid carbon dioxide — CO₂ at atmospheric pressure sublimates at -78.5°C, absorbing 571 kJ/kg of heat in the process. It is thermally magnificent for ultra-cold applications: frozen pharmaceuticals, frozen seafood, laboratory samples. Nothing in the passive cold chain delivers more cooling capacity per kilogram.
But the carbon accounting is complex.
Where Dry Ice Carbon Comes From
Commercially produced dry ice is manufactured from CO₂ that is a byproduct of industrial processes — ammonia production, ethanol fermentation, and petroleum refining are the primary sources. The logic has been that this CO₂ would be emitted anyway, so capturing it for dry ice production is carbon-neutral or even carbon-negative relative to atmospheric release.
This argument has merit in specific supply chain contexts, but it depends on the counterfactual: what would have happened to that CO₂ if it were not captured? In some industrial configurations, the CO₂ would be sequestered or converted. The “byproduct” framing is not universally accurate.
Furthermore, dry ice production requires significant energy for compression, purification, and solidification. The carbon intensity of that energy — which in Australia’s grid is still substantial despite the renewable transition — adds to the overall emissions figure.
The Sublimation Problem
Every kilogram of dry ice that sublimates releases 1 kg of CO₂ directly into the atmosphere. In a well-designed cold chain, this happens at the destination — but in an over-specified package, significant sublimation occurs in transit before the product arrives. Dry ice that sublimates in a van contributes to the vehicle’s interior CO₂ concentration (a safety issue) and releases emissions with no thermal benefit to the product.
The thermal efficiency of dry ice is only as good as the packaging system it operates within. In a poorly insulated package, a kilogram of dry ice may provide only 60–70% of its theoretical cooling capacity to the product, with the remainder wasted through heat ingress and sublimation inefficiency.
Gel Ice Packs: The Full Lifecycle Picture
Gel ice packs — whether disposable or reusable — use water mixed with a superabsorbent polymer (typically sodium polyacrylate) or a phase change material to store and release thermal energy. The phase change of water at 0°C provides 334 J/g of latent heat, while specialised PCMs can be formulated to freeze and melt at specific temperatures (2°C, 5°C, 8°C) matching pharmaceutical or food cold chain requirements precisely.
Manufacturing Carbon
A standard 500g gel pack carries embodied carbon primarily from three sources: the plastic packaging film (typically polyethylene or multi-layer laminate), the superabsorbent polymer, and manufacturing energy. Estimates place the embodied carbon of a disposable 500g gel pack at approximately 80–150g CO₂e depending on film thickness and polymer content.
For context: a standard 1kg block of dry ice has an embodied carbon footprint of approximately 1–2 kg CO₂e when accounting for production energy and the CO₂ it will release upon sublimation.
Reusable vs Disposable
This is where lifecycle analysis becomes decisive. A reusable 1kg gel pack with a 150g CO₂e manufacturing footprint, used 50 times over its life, has a per-use carbon cost of 3g CO₂e. A disposable gel pack with the same footprint, used once and landfilled, costs 150g CO₂e per use — fifty times higher.
The environmental case for reusable gel packs in closed-loop supply chains — where the pack returns to the shipper — is overwhelming. The challenge is logistics: return systems add complexity and cost that can erode the sustainability benefit if vehicles are running empty on return legs.
End-of-Life
Disposable gel packs present an end-of-life problem. Most are not recyclable in kerbside programs — the multi-material laminate film and the hydrogel filling are both problematic. Some facilities will accept them as general waste, where the hydrogel can absorb significant landfill moisture. Few consumers properly cut and drain packs before disposal, meaning the gel often ends up in the plastic stream where it contaminates recycling.
Two-ply disposable dry ice packs with food and medical grade credentials address some of these concerns through more readily separable materials, but the fundamental challenge of mixed-material disposal remains.
Phase Change Materials: The Precision Option
True phase change materials (PCMs) — materials engineered to freeze and melt at specific temperatures — represent the third category of cold chain thermal media. Unlike water-based gel packs (which always phase change at 0°C regardless of your target temperature), PCMs can be formulated to match your cold chain precisely.
A PCM designed to melt at 5°C, for example, maintains product temperature at or near 5°C throughout its melt cycle, eliminating both the risk of product freezing (from 0°C ice) and the risk of product warming (from early thermal depletion). For pharmaceutical applications requiring 2–8°C compliance, purpose-formulated PCMs are thermally superior to standard gel packs.
The carbon cost of PCMs is higher than water-based alternatives — the organic compounds used in phase change formulations carry greater embodied carbon than polyacrylate hydrogels. But for high-value pharmaceutical shipments where product loss from temperature excursion costs thousands of dollars, the lifecycle cost is often strongly positive.
Insulation Materials: The Overlooked Variable
The thermal medium (dry ice, gel pack, PCM) is only half the equation. The insulation material that surrounds it determines how efficiently that thermal capacity is used — and has its own significant carbon footprint.
Expanded Polystyrene (EPS)
EPS foam is thermally excellent (k ≈ 0.033 W/m·K) and inexpensive. But its embodied carbon is significant — approximately 3–5 kg CO₂e per kg of EPS, and end-of-life recycling infrastructure in Australia is limited. Many EPS foam packaging pieces end up in landfill or, worse, as litter that fragments into persistent microplastic pollution.
MPET / Foil Bubble Liners
Thermal foil bubble liners combine reflective MPET film with bubble wrap insulation. Their embodied carbon per unit is generally lower than EPS for equivalent packaging volume, and some formats are more readily recyclable through specialist streams. Performance is adequate for 2–8°C applications with gel packs in typical Australian transit times.
Wool / Natural Fibre Liners
Natural fibre insulation has gained traction as a sustainable alternative. Wool has genuinely favourable lifecycle credentials — it is renewable, biodegradable, and has reasonable insulative performance. However, wool liners typically require more volume to achieve equivalent thermal performance compared to foam or foil alternatives, and the cost premium is significant.
Recycled Paper Pulp (Ecosafe)
The Ecosafe insulated mailer range uses recycled paper pulp as the insulative element. Paper pulp’s thermal conductivity is higher than EPS (less insulative per unit thickness), but the recyclability credentials are genuinely strong — these liners can be processed through standard kerbside paper recycling streams. For chilled products with transit times under six hours, they are a compelling sustainable option.
Carbon Comparison: A Practical Example
Consider a 2kg chilled pharmaceutical shipment from Sydney to Melbourne, requiring maintenance at 2–8°C for 24 hours including a 4-hour doorstep dwell.
Option A: Dry ice (500g) + EPS foam box
Dry ice CO₂ release: 0.5 kg CO₂
Dry ice production energy: ~0.2 kg CO₂e
EPS box (500g): ~2.0 kg CO₂e
Total: ~2.7 kg CO₂e
Option B: 2 × 500g gel packs (disposable) + MPET liner
Gel packs: ~0.3 kg CO₂e
MPET liner: ~0.4 kg CO₂e
Total: ~0.7 kg CO₂e
Option C: 2 × 500g reusable gel packs (50-use lifecycle) + recyclable paper liner
Gel packs (per use): ~0.006 kg CO₂e
Paper liner: ~0.15 kg CO₂e
Total: ~0.16 kg CO₂e
The carbon reduction from Option A to Option C is approximately 94%. The thermal performance of Option C is adequate for chilled (2–8°C) applications but insufficient for ultra-cold requirements where dry ice remains necessary.
Australian Regulatory Context
Australia’s Safeguard Mechanism — which applies to facilities emitting over 100,000 tonnes CO₂e per year — creates direct financial incentive for large cold chain operators to reduce emissions. Below that threshold, voluntary ESG reporting and customer requirements are the primary drivers.
The ACCC has also tightened enforcement of environmental claims, with the 2023 Green Marketing Guidance making clear that vague claims like “eco-friendly” or “sustainable” require substantiation. Cold chain businesses making environmental claims about their packaging need documented lifecycle data, not marketing assertions.
Making the Right Decision for Your Cold Chain
The carbon calculus of cold chain packaging is not a single answer — it is a function of:
- Required temperature range (ultra-cold requires dry ice; chilled can use gel packs or PCMs)
- Transit time (longer transits require more thermal mass, regardless of medium)
- Supply chain circularity (closed loops enable reusable solutions)
- Product value (high-value products justify premium low-carbon solutions)
- Volume (high-volume operations can achieve economies in return logistics)
The Dry Chill range spans disposable and reusable thermal media, recyclable and conventional insulation, and purpose-built pharmaceutical formats — enabling a genuinely optimised solution for each application rather than a one-size-fits-all approach. For specific carbon footprint data on any product in our range, contact our team.
The cold chain does not have to be as carbon-intensive as it has historically been. The technology exists. The specification knowledge exists. The decision is yours to make.