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  • Michael Lowe

Decarbonising the Cold Chain

Sunswap’s mission is to decarbonise the world’s cold chain. But what does that mean and how can it be done? Before you can begin to answer those questions, it is essential to understand the current technology used in the industry.

Large parts of the cold chain are powered by the grid due to their stationary nature; cold stores such as warehouses or the fridges used in supermarkets use standard mains power to operate. Their carbon footprint is primarily defined by two factors, their energy consumption and the carbon intensity of the grid. In recent weeks and months, the grid’s carbon intensity has reduced significantly, particularly because the UK didn’t rely on coal for power generation for 68 days between April and June. Huge investment and technological advancements are being seen in the renewable energy sector which will continue the reduction of carbon emissions in some parts of the cold chain.

UK's Grid Carbon Intensity since 2009 (data: National Grid ESO)

While cold stores and distribution centres have benefitted from a lower grid carbon intensity, another link in the chain, transport refrigeration, has seen an increase in usage. Figures from Kantar show demand for supermarket food was up 14.3% on average by the middle of May due to lockdown measures, resulting in an upturn in the use of diesel transport refrigeration units (TRUs). Historically, there has always been a heavy reliance on diesel TRUs with no real alternative being available to fleet operators.

One common ‘quick-fix’ solution used by retailers and logistics companies is to remove the secondary diesel engine powering the fridge and take power, either hydraulically or electrically, from the tractor unit’s engine instead. It is true that this engine is more efficient, but it is still burning diesel. It is also true that moving to the increasingly popular biomethane tractor units helps to reduce emissions, especially particulates and NOx. But this technology faces sizeable challenges in its scalability.

Two different activities are required to decarbonise the cold chain. First, the industry must begin to properly quantify how and when it is burning diesel. Retailers and logistics companies have a fleet-level view on their fuel consumption but that doesn’t tell them much other than overall expenditure. Operators need a unit and duty-cycle level view providing a detailed summary of performance. This allows businesses to cut down on their diesel consumption by optimising operations through a number of potential avenues, for example by highlighting inefficient units that should be replaced or by quantifying the cost of extended door openings.

Understanding fuel consumption is a short-term solution that can only take us so far, ultimately the industry must stop burning fuel. For this to become a reality, operators need a viable zero-emission alternative - one that competes on cost and performance. When considering round-trip efficiency, and therefore the cost of cooling, electric TRUs are the best solution. They do not rely on fluids for energy and therefore expensive biomethane or cryogenic plants. Electric TRUs leverage the efficiency of large-scale generation at a grid level and can generate their own additional energy through the use of solar panels.

Decarbonising the cold chain is a considerable task due to the size and complexity of the process. With large parts of the chain relying on increasingly clean grid energy, it is imperative to address the other links. By tackling transport refrigeration, it is possible to achieve a step-change reduction in overall carbon and particulate emissions from the cold chain. Whilst the units that take energy from the vehicle’s main engine may reduce emissions, they will never eliminate them. If we want a truly decarbonised cold chain, we must adopt electric TRUs.


Michael Lowe

Co-founder & CEO at Sunswap

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