Evaluation and forecast for the future of E-fuels and E-

and E-mobility, an impartial evaluation is necessary to make a reliable forecast for the future of the transportation and energy sector. Currently, biofuels like bioethanol and biodiesel are just used in blends with petrol and diesel fuels. Further, in only a few cases worldwide, E-fuels are produced on an industrial scale, but still from fossil resources. In China and South Africa, for example, Fischer-Tropsch hydrocarbons and methanol are obtained from coal, whereas Malaysia and Qatar use natural gas to produce these E-fuels.

With international climate objectives prescribing the reduction of CO2emissions until 2050 by 80% compared to 1990, fundamental technological changes are still necessary in the transportation sector. Within the Effort Sharing Decision, Germany committed itself to increase the ratio of renewable energy used in the transportation sector to 10% until 2020.

To curtail the expectations and to accurately reflect the preliminary up-to-date status in Europe, the emissions caused by traffic increased by 20% compared to 1990. Solely considering the CO2 emissions in German traffic, the values remained nearly constant during the last 27 years [127].

There are about 45.8 million passenger cars in Germany with an average age of 9.3 years.

Governmental incentives on EVs are thus not effective due to the slowly changing traffic sector. The current stock of EVs in Germany amounts to about 200 000 passenger cars, with forecasts predicting an increase to 6 million EVs until 2030, which would just account for about 13% of the total amount of passenger cars [156]. This already indicates that combustion engines will most likely be still the main propulsion technology in the near future. As the electrification of heavy-duty vehicles, ships and planes is presumed to be not feasible, they will also remain consumers of liquid fuels in the future. Therefore, just considering the contribution of E-mobility, the international climate objectives cannot be fulfilled. Since a change in consumer behaviour is not conceivable, the DECHEMA, a German association dealing with the development of chemical technologies, proposed three different approaches to solve these issues in Germany. Firstly, the fleet consumption could be distinctly reduced by combustion engines with significantly higher efficiencies.

These progresses, however, did not lead to lower CO2 emissions in the past, as current passenger cars tend to possess more powerful engines, to be heavier and to provide greater comfort as well as passenger security. Secondly, the amount of biofuels used as alternative to fossil fuels should be increased. Since the DECHEMA mainly promotes E-fuels due to its industrial cooperations with E-fuel producers, biofuels are just mentioned in passing.

To increase the share of biofuels in the fuel sector, however, much larger cultivation areas are necessary. The third and as most promising promoted approach is the implementation of E-fuels into the transportation sector. The DECHEMA emphasises that electricity from sustainable resources is essential for the production of E-fuels. With the plans of the German government to further extend renewable energy in the electricity sector, valid since 2016, a maximum of 47.5 TWh from photovoltaics and 170.6 TWh from wind energy could be produced in 2030, assuming current technologies. Further contributors are hydro power and biogas, whose capabilities are mostly exhausted, and other energy sources like geothermal energy, whose shares are not considerable. The share of renewable sources on the total electricity used in the German transportation sector could thus be up to 53.7%.

Nevertheless, this amount can just be achieved, when the necessary electricity of other sectors is excluded. To make this desperate situation even more obvious, an available amount of 25 TWh sustainable electricity for the production of E-fuels in 2030, which is a reasonable value, leads to a maximum of 1 million tonnes of E-fuel. Considering the fuel consumption of solely Germany, which is currently above 50 million tonnes of fossil fuel, more than 1 000 world-scale power plants would be necessary to produce enough electricity for the sufficient production of E-fuels [127].

Due to this critical situation, the DECHEMA suggests the development and construction of industrial complexes that produce sustainable electricity, which is subsequently used to synthesise E-fuels. Such complexes could be located on coasts next to offshore wind

farms or in Southern Europe close to photovoltaic power plants. So far, there are only a few projects promoted by European governments like the Power-to-X (P2X) project of Germany [157]. Besides huge costs to build these complexes and the lacking collaboration of the affected industrial sectors, which is also known as integrated energy, the availability of the required resources, in particular CO2 and water, is the main challenge. Since highly purified CO2 is necessary in huge amounts for the synthesis of many E-fuels, other companies that produce CO₂ continuously like cement plants should be close. Assuming that the total CO2 emissions will distinctly decrease in the next years due to the interna-tional climate objectives, however, its availability will become even worse. When including Southern Europe, the high amounts of required water should not be underestimated. As known from China, for example, water is the limiting factor in arid regions due to the high consumption of the chemical industry.

This detailed evaluation shows that, although E-mobility and E-fuels have already been dominating the media since a few years, they are still far away from a comprehensive implementation. This conclusion leads to the confirmation that, at least currently, biofuels are a significantly better alternative to fossil fuels. In particular, the production processes should be kept simple and at best, existing and industrially applied processes should be combined to avoid problems regarding integrated energy.