Six theories on climate neutrality in the European transport sector

To date, the impact of vehicles on the climate was solely determined on the basis of CO₂ emissions output by the vehicle’s exhaust system while in operation. However, this approach, dubbed ›tank-to-wheel‹ by experts, does not go far enough. Not only does it fail to consider the CO₂ emissions generated during vehicle production, it ignores all other greenhouse gases resulting from the generation and provision of the energy carriers and their storage, as well as the associated infrastructure. Effective climate protection requires all these emission sources to be taken into account in a holistic environment footprint, known as a ›cradle-to-grave‹ approach. Limiting emissions solely to a tank-to-wheel analysis – as is currently specified – can result in increased cumulative greenhouse gas emissions overall.

In the majority of existing studies, the greenhouse gas emissions resulting from the generation and provision of the energy carriers were amortised over the duration of their use. This conventional approach to balancing not only precludes an objective comparison, but also prevents the optimisation of the energy chain in its entirety. In reality, the remaining CO₂ budget is impacted immediately at the time when the plants are constructed – and not 20 years later. It is of paramount importance that climate-relevant emissions generated due to mobility demands are balanced completely.

The FVV study analyses a total of 21 combinations of powertrains, energy carriers and efficiency technologies in vehicles. For each combination, a scenario was created in which wind and solar energy was generated entirely within Europe, and a scenario where the energy was generated outside Europe, resulting in a total of 42 scenarios. If we include all emissions from the development of the energy infrastructure and the entire life cycle of the vehicle, the cumulative CO2 emissions of the calculated transformation paths only differ slightly up to 2050, provided that only emission-free vehicles can be registered as of 2033. The difference between the observed paths is around 14 per cent and, in light of the remaining uncertainties in the forecast, does not represent a decisive criterion for a certain technology.

In other words: it is not the powertrain technology, but the availability of climateneutral energy carriers that will decide just how quickly and comprehensively the fleet of existing and new vehicles is actually climate-neutral. In addition to sufficient capacities for generating solar and wind energy, the quick establishment of a green hydrogen economy is of crucial importance in all scenarios. This also explicitly applies to the hypothetical scenario of a complete transition to battery electric vehicles powered by electricity generated in Europe. In order to always meet the electricity demands in such a scenario without falling back on fossil energy carriers, hydrogen buffer storage providing energy during cold, dark periods with low wind – based on an electrolysis capacity of around 1,000 gigawatts in total – will be required.

If it is necessary to introduce new vehicle technologies in order to enable climate-neutral mobility, the conversion to sustainable energy carriers is inevitably linked to the fleet turnover rate. As cars are kept for an average duration of 17 years, from 2033 only emission-free cars and small commercial vehicles can be registered if the goal is for road traffic to be completely based on sustainable energy sources in 2050. If the share of newly registered cars reaches 100 per cent by 2033 and every single new vehicle is powered solely using renewable energy during the ramp-up phase – which is far from the case today – a 28 per cent share of fossil energy in the transport sector can be replaced by the year 2030 without negatively affecting other sectors.

However, even if the ambitious goals outlined in the FVV study are met, the existing fleet powered by fossil fuels still makes up a dominant share of cumulative CO₂ emissions. Regardless of the powertrain technologies used in the new, climate-neutral vehicles, these emissions make up around 70 per cent of the total mobility-related emissions based on the assumed ramp-up duration. This would result in Europe’s entire greenhouse gas budget, which would enable adherence to the 1.5°C target*, being exceeded as early as 2031 or 2032 – regardless of the scenario model. Our mobility needs alone will account for two thirds of the greenhouse gas budget available to all sectors in Europe in order to limit the temperature increase to 1.75°C – and this is before heating a single house, or manufacturing any other industrial product outside the mobility sector. To prevent this from happening, the mobility sector must stop using fossil energy sources sooner than the vehicle fleet can be replaced with vehicles using new powertrain technologies.

It is therefore an absolute necessity to find solutions that reduce harmful emissions from existing vehicles. According to the current state of the art, and to avoid any appreciable impact on mobility, this will largely only be possible through the use of compatible synthetic fuels (known as drop-in fuels).

* Due to the imprecision of the climate models upon which they are based, the emissions budgets are probable estimates for which a certain average global temperature increase will occur. A probability of 67 per cent is given for the specifications above.

The FVV study consciously works with what are known as ›100 per cent scenarios‹, as these enable an excellent comparison of the environmental impact of individual technologies throughout the entire energy chain and the vehicle life cycle, while also allowing bottlenecks to be determined. Comparing the demand for critical raw materials with the available reserves and resources shows that – even assuming a high recycling rate – certain raw materials will become very scarce if the rest of the world follows the European model and uses the same technologies. The raw materials in question depend on the selected combination of energy carrier and powertrain.

For example, if the selected technology is battery electric vehicles using the currently dominant battery technology (lithium-ion batteries with nickelmanganese-cobalt cathodes), cobalt and lithium availability will be the limiting factor for the ramp-up speed, and this will have a significant impact on the cost of the batteries. Moving to solid-state batteries with a pure lithium anode will significantly exacerbate the scarcity of resources in the lithium supply chain. For fuel cell powertrains, the availability of platinum is a highly limiting factor. In a scenario in which the entire world transitions to 100 per cent fuel cell use, all known resources will not be sufficient, let alone those that can be tapped in an economically viable manner. No such bottlenecks are currently known when it comes to the use of hydrogen or synthetic fuels in combustion engines.

The global potential of sustainable solar and wind energy exceeds the entire primary energy demands of humanity in its entirety several times over. This energy must only be harvested, prepared and distributed using methods that enable technical usage, particularly in the transport sector. This also applies to all mobility transition paths observed in the study – however, the total energy demands for individual energy chains differ significantly. A 100 per cent transition to synthetic fuels used in combustion engines would triple or quadruple energy demands compared to pure battery electric mobility. However, this does not mean that up to four times as many wind energy power plants need to be built. If these fuels were to be produced in regions with plenty of wind and solar energy, the capacity required to generate green electricity would only differ by a factor of two to three.

The additional economic costs to produce energy for climate-neutral mobility are not determined by the amount of energy, but by the capacities required. The increased costs are, however, overcompensated for by the higher vehicle costs associated with battery electric mobility. All things considered, the total costs for an internal combustion engine vehicle powered by synthetic fuels are significantly lower than those for a battery electric vehicle.

All scenarios require a significant expansion of green electricity production. Even the most energy-efficient scenario – the transition to 100 per cent battery electric mobility – will require Europe to generate 1,100 gigawatts of energy in 2050 to cover all of its mobility demands. To compare: according to the International Renewable Energy Agency, the capacity for solar and wind generation in Europe for all sectors will increase to just 690 gigawatts by 2030.

If European politics continues to ignore the existing vehicle fleet and only measures the climate compatibility of new vehicles based on tank-to-wheel emissions, the transformation in the transport sector will be doomed to fail. New goals must be defined if we hope to quickly reduce the CO₂ emissions generated by mobility needs. Within the scope of a cradle-to-grave observation, these goals should consider the emissions generated when expanding the energy infrastructure and thus also extend beyond a well-to-wheel approach. European politics must create a market economy framework for the transport sector which then enables multiple technology paths to be established simultaneously. If multiple paths are pursued with the objective of withdrawing from the use of fossil energy carriers, the ramp-up speed will probably also be quicker.

This approach not only benefits climate protection, but also minimises the total economic costs which are dominated by vehicle costs. Cost comparisons that do not include the vehicle costs must therefore be viewed critically. A technology-neutral approach will also ensure that individual mobility remains affordable for a wide section of the population.