Truck diesel fridge emissions quantified

London, UK: Truck fridges can produce as much as double the Nox emissions, five times the particulates, and up to four hundred times the particle number compared with emissions from the truck exhaust of a Euro 5 engine, according to a new report from Zemo Partnership.

Zemo’s study, covers results from the first phase of its research, combining test and survey results to provide UK-wide estimates of the overall fuel consumption and environmental impacts of diesel auxiliary engines.

Accurate data is in short supply concerning the refrigerated truck parc but the report goes some way to estimating the size of the truck parc and the age and number of refrigerated trailers.

Fridge age is crucial with pre-1919 made fridges considerably more polluting. The reports estimates that half of fridges in use are over 5 years old.

The test results indicate that compared with the vehicle’s Euro VI compliant propulsion engine, a single diesel auxillary engined fridge fitted to a Euro VI HGV (in typical city/urban conditions) would:

  • Consume around 10% of the fuel (slightly more if made pre-2019).
  • Produce about 10% of the GHG emissions (slightly more if made pre-2019).
  • Produce at least double the NOx if pre-2019 and at least 1.5 times more if post-2019.
  • Emit at least five times the particle mass (PM2.5) if pre-2019 and around triple if post-2019.
  • Emit about 400 times the number of particles if pre-2019 and around 300 times if post-2019.

Zemo research co-author Emily Stevens said: “It’s clear that auxiliary transport refrigeration units and other ancillary engines can significantly add to transport-linked emissions of greenhouse gases as well as those of local pollutants.  The level of these emissions can be disproportionately large compared with those from the vehicle’s engine.

“As this study makes clear, there are opportunities for achieving significant emissions reductions in this area. The next stage of our study will identify the most effective ways to achieve these reductions.”

The next stage of the study will extend the work to consider the van sector and investigate the energy and emissions of alternative technologies, to understand what can be done to reduce the environmental impacts of diesel-engined truck fridges and from other ancillary engine uses such as road sweepers. The final report is due in November 2024.

Zemo’s report HGV Auxiliary Engines: Baseline auxTRU testing and modelling of UK impacts is available as a free download.