Auxiliary diesel heaters are commonly used in all types of vehicles in cold climates and conditions around the world. Electric buses used in public transport utilise diesel-burning auxiliary heaters to provide thermal comfort for passengers under cold weather conditions while maintaining the operational range otherwise reduced by electric heating. However, the downside of utilising diesel burners is that they cause similar exhaust pollutants to conventional diesel vehicles. Because the emission control for auxiliary heaters is lax, the diesel burners typically lack any exhaust aftertreatment (EAT), resulting in potentially high local emissions. As the public transport sectors around the world seem to transit from traditional internal combustion engine-vehicles to battery electric applications, the significance of the emissions caused by diesel auxiliary heaters is continuously increasing. EVs are generally considered zero-emission vehicles but the implementation of diesel burners is evidently conflicting with this concept. Nevertheless, publicly available experimental results from studies around this topic are surprisingly limited. The data of the few available publications are not directly comparable because there is no direct procedure or protocol for determining the exhaust pollutants from auxiliary heaters in real-world conditions at present. As a result, assessing the direct effect of the pollutants caused by electric vehicles utilising auxiliary heaters in the public transport is challenging. This study addresses this problem by introducing two methods for measuring auxiliary heater emissions; first, a field-test method that is applicable for a quick screening of the emissions of multiple heater units; secondly, a laboratory test method for a more detailed emission characterisation in a simulated real-world operation environment. In these experiments, the primarily objective was to study the emissions of the auxiliary heaters, including CO₂, CO, NO_x and soot. The heater operation was found to be cyclic with numerous start-ups during its typical operation. The cyclic operation resulted in concurrent emission peaks in CO and soot. Measurements of actual operation showed auxiliary heater utilisation rates similar to the controlled measurements, although the whole temperature range of the controlled measurements was not reached in real-world conditions. The measurements conducted during the field screening revealed high variations between emissions of individual units. A further screening of auxiliary heaters would provide a better outlook for the mitigation of their emissions.

The baseline assessment analysis for total cost of ownership of the pilot demonstrations of the ESCALATE project was carried out for four different powertrain configurations, dealing with modular and scalable powertrains for various vehicle configurations in long-haul trucking. The baseline TCO methodology and results for battery electric trucks (BETs), fuel cell electric trucks (FCETs) and FC range-extending BETs are analysed based on the final designs of the demonstrator vehicles and their foreseen pilot use cases and operational scenarios. As real operation data is not yet available, the analysis relies on energy use and pilot mission analysis through simulation. Overall, the TCO analysis shows several key factors affecting the relative competitiveness of the different zero-emission powertrains and vehicles. Long-haul operations pose clear challenges to vehicle design and long-range vehicles on single charge or refill show increased curb weight, limiting allowable payload due to GVW limits. The best payload capacity is shown for opportunity charging BETs and FCETs. BETs are generally the closest competitor to conventional trucks, but a key factor is the relative energy price difference between diesel, electricity (private or public) and hydrogen. Energy sourcing will be an important factor for end users to enable competitive shift to zero-emission options. Access to cheap private electricity or local green hydrogen may facilitate a choice between the options.