Technological CO2 Mitigation Strategies for the European Transport Sector

In the 19th century, the use of fossil fuels triggered the industrial revolution. What led to great prosperity has turned into a crisis for our planet. Climate change poses an existential threat to humanity and plenty of ecosystems. The good news is: We have solutions at hand to solve this crisis. This work analyses CO2 mitigation pathways for the automotive, the aviation, and the shipping sector in Europe. Currently, these three sectors have an annual demand for fossil fuels (mainly diesel, gasoline, and jet fuel) of roughly 3’500 TWh and are responsible for CO2 emissions of 917 Mt p.a., with 60% stemming from the automotive sector, and about 20% each from aviation and shipping. In the future, these fossil fuels will have to be replaced by renewable energy carriers, in this thesis defined as renewable electricity or fuels produced from renewable electricity (so-called e-fuels), including hydrogen, ammonia, methane, methanol, and diesel. Renewable electricity could become for this century what coal and oil were for the last. If the transition to carbon-neutrality is mastered until 2050, it could shift the primary energy demand massively towards aviation and shipping. Until 2050, the electrification of transport could more than double the current electricity consumption of Europe, from roughly 3’000 TWh to about 7’500 TWh. The automotive sector could only have a share of 10% of this electricity demand in 2050, while the share of shipping could rise to almost 40%. Aviation could be the predominant electricity consumer with a share of over 50%. These numbers represent a scenario in which electric cars, ships powered by liquefied hydrogen or ammonia and aircraft running on e-jet fuel prevail, for which this thesis finds evidence. The additional electricity demand would require massive investments in renewable electricity generation assets in Europe, exceeding currently installed capacities of PV and wind power plants by a factor of 5-8. Currently, aviation and shipping are far from contributing their fair share to the target of limiting global warming to 2.0°C. Only the automotive sector is roughly on track, if the current emission reduction trajectory until 2030 imposed by the European Union were to continue beyond that year. The aviation sector is on its way towards cumulative emissions (2021-2050) of roughly 7.5 Gt CO2, compared to its maximum permissible amount of emissions for a 1.5◦C/2.0°C target –its carbon budget– of 1.1/3.8 Gt CO2 (derived from the global carbon budget assuming even distribution across countries and sectors according to their population and emission shares). The situation for the shipping sector is similar. Both, aviation and shipping, lack ambitious emission targets. Given their increasing relevance in the future, accelerating their transition to renewable energy carriers could be even more important than tightening targets for the automotive sector. Long lifetimes of existing vehicles commit current fleets to high locked- in emissions. The turnover time of the ship fleet towards new propulsion systems is constrained by ships’ average lifetimes of 25-40 years. Even if all newly built ships were powered by carbon-neutral energy carriers from 2021 on, the locked-in emissions of the existing vehicle stock would overshoot the sector’s 1.5°C carbon budget by 100%. The same phenomenon can be observed for cars. Even if all newly sold cars were full-electric from 2021 on, the sector’s 1.5°C carbon budget would be exceeded by roughly 40%. Blends of e-diesel for the existing vehicle fleet, early retirements of existing vehicles or retrofits could close this gap. Otherwise, other sectors will have to contribute even more towards a 1.5°C target. The cost gap between fossil and renewable energy carriers has to be closed through policies and industry R&D as soon as possible if climate targets are to be met. In particular the production costs of e-jet fuel exceeds cur- rent market prices of fossil jet fuel (averaged over the last seven years) by a factor of about 5-8, depending on the production location in Europe. At current emission rates, the automotive sector, aviation, and shipping will have used up their 1.5°C carbon budgets within the next six years. Fast, decisive action is needed to turn the tide and set a new course towards 1.5°C. This thesis provides technology pathways on how the transition to carbon-neutrality could be mastered.