Reduction of future nitrogen oxide and particulate emissions in North Rhine-Westphalia through utilisation of alternative fuels and propulsion systems

This thesis aims to answer the research question of how alternative fuels and powertrains can reduce nitrogen oxide (NO${}_x$) and particulate matter (PM) emissions in hotspots. The thesis proposes a new spatial bottom-up model that computes mileages and local pollutants of road transport, inland waterway transport, rail transport and air transport for North Rhine-Westphalia (NRW) as representative case study. The model is organised in sub-modules. For instance, one module determines mileages and transport performances for each section of the transport networks using timetables, flight schedules, data from the Federal Statistical Office and a developed statistical model. Another module calculates emissions on each network section taking different vehicle classes, vehicle sizes, emission technologies, powertrains and fuels into account. Finally, a novel module balances emissions in urban areas for a following analysis. Besides the calculation of current emissions, several scenarios for future developments of the transport sector and their emissions were considered in the case study. Boundary conditions for future scenarios were set using forecasts of traffic performances for inland waterway transport and air transport, a developed model approach for forecasting road transport mileages, and devised approaches for determining fleet developments. The assumption for the reference scenarios was the continuation of using conventional fuels. The other tested scenarios included various alternative fuel options and powertrains, which were selected based on a novel methodology for selecting promising future fuel options. More specifically, the fuel options for road transport were Fischer-Tropsch diesel/ hydrogenated vegetable oil, Methanol to Gasoline, natural gas, dimethyl ether, hydrogen in fuel cells and electric power. Meanwhile, the fuel options for inland waterway transport were natural gas as well as hydrogen in fuel cells and internal combustion engines and for avitation the fuel option was Fischer-Tropsch kerosene. These and the reference scenarios were simulated with the proposed model. The result of the case study was that the urban areas of Aachen and Wuppertal as well as urban areas in Rhine and Ruhr regions are the most critical current emission hotspots in North Rhine-Westphalia. Road transport currently accounts for the largest share of pollutants emitted in emission hotspots. Inland navigation shows moderately high shares in current NO${}_x$ and PM2.5 emissions in the vicinity of the Rhine, while rail transport is only responsible for larger shares of the less harmful PM10 emissions due to abrasion. Air transport only produces a moderately high share of emissions in the vicinity of the international airport Düsseldorf. The results of this work already show a strong and respectively moderate reduction in combustionrelated emissions from road and inland waterway transport for further utilization of conventional fuels, whereas those from air transport increase slightly. Overall, this will lead to a future easing of NO${}_x$ emissions away from the Rhine region and the airports of Cologne and Düsseldorf. Furthermore, the share and significance of abrasion-related PM emissions will increase strongly in the future. In the short term, the with existing vehicles compatible drop-in fuels Fischer-Tropsch diesel and Fischer-Tropsch kerosene have a high reduction potential. However, it will be mandatory to switch to hydrogen- or electricity-based powertrains in the long term for larger emission reductions. When discussing these results, it became clear, that the low technology readiness level of alternative low emission propulsion systems for inland waterway transport and air transport is critical. Moreover, guidelines for abrasion emissions are needed to encourage the state of research on these. It is still an open question how a large market share of electric vehicles will affect local abrasion emissions. In conclusion, the results of this work are a robust basis for devising strategies for air pollution control in current emission hotspots and a further criterion for the selection of promising future fuels and powertrains.