ZECC Transport roadmap

In this roadmap we question how the refrigerated food transport sector can decarbonise and rapidly reach zero carbon emissions. As part of the work, we provide independent reviews of 29 different technologies/strategies that refrigerated transport vehicles could apply to reduce carbon emissions and energy consumption. Scope 1 and 2 emissions are covered which encompass emissions from fuel used, emissions from leakage of refrigerants (scope 1) and emissions from electricity provided from the national grid (scope 2). Scope 3 emissions have not been considered.

Technology/strategy reviews were used to identify the individual technologies/strategies that had the most potential to reduce greenhouse gas (GHG) emissions in refrigerated transport vehicles. Only technologies with a high technology readiness level (TRL) were considered, this meant that technologies/strategies included were already available on the market. The carbon emissions from those technologies/strategies that had a low TRL were often not available or had very varied application times and the claimed savings often varied widely. Therefore, these technologies/strategies were very difficult to quantify. Results were presented as potential carbon savings (high/medium/low) and payback time.

Mathematical modelling was then used to assess impacts from 2020 through to 2050 taking into account changes due to global warming and changes in the grid carbon emission intensity as well as the impact of the combined technologies/strategies. Six different vehicle types with associated varied delivery missions were considered.

The vehicle missions considered were:
1. Long haul medium temperature (MT)
2. Long haul low temperature (LT)
3. Regional transport medium temperature
4. Regional transport low temperature
5. Last mile multi-temperature
6. Last mile frozen thermal energy system (TES)

Baseline distances, speed, journey duration, number of stops and refrigerant in the transport refrigeration unit (TRU) were varied across the missions (see Table 8) in the UK. The baseline vehicles were diesel-powered internal combustion engine vehicles using R452A as the refrigerant.

The technologies modelled were:

1. Adding door curtains (60% infiltration reduction).
2. Better vehicle insulation. The reference value for k was assumed to be 15% better than the least stringent requirement of ATP agreement for the corresponding temperature class (K = 0.60 W/m2 K for chilled applications and K = 0.35 W/m2 K for frozen applications.

3. Electrification of the TRU.
4. R744 TRU.
5. R290 TRU.

Technologies were then combined as follows and energy and carbon emissions calculated:

1. Door curtains and better insulation with a R744 TRU.
2. Door curtains and better insulation with a R290 TRU.
3. Door curtains and better insulation with electrified R744 TRU.
4. Door curtains and better insulation with electrified R290 TRU.

Results from the reviews and modelling identified routes for refrigerated transport vehicles to reduce emissions and enabled the creation of a decarbonisation roadmap through to 2050. Climate alone had negligible impact on the overall carbon emissions from the baseline long haul and regional transport vehicles. For the last mile multi temperature vehicles the difference in emissions by only considering climate change for the baseline vehicle between 2020 and 2050 were 1%. The last mile frozen TES where electricity was used to charge the TES showed reduction in GHG emissions of up to 2.5%.

The application of low global warming potential (GWP) natural refrigerants had a large positive impact and R290 has slight advantages over R744. To be able to get close to zero carbon today, several technologies needed to be applied together. Better insulation, curtains (for vehicles where there were door openings), low GWP natural refrigerants and electrification were all needed to get close to zero carbon. In the future as the grid decarbonises it is possible to almost get TRU emissions to zero carbon in the UK.