Renewable Energies in Mobility: The Potential of Synthetic Fuels Based on CO₂

Authors

Prof. Dr. R. Schlögl, Fritz Haber Institute of the Max Planck Society, Berlin; Max Planck Institute for Chemical Energy Conversion, Mülheim a. d. Ruhr

Year

2018

Print Info

Fortschritt-Berichte VDI, Series 12, No 807

Summary

Today many proposals are made with regard to the production of synthetic fuels (SF). These SF are competing with electric mobility, which has developed at a very rapid pace. The large variety of options, the inadequate availability of the required materials and a fundamental distrust of exaggerated promises are hampering a fast and practical testing of SF structures. Therefore, the first part of this lecture will outline a framework of conditions under which the potential of SF can be assessed. Questions such as how these energy carrier materials can be systematically integrated into a supply system for renewable energies are of paramount importance. Following a brief survey of the chemical concepts for the generation of synthetic fuels, this paper will focus on the reaction sequences during the chemical reduction of CO₂ to target molecules which could be relevant for SF production. Results described in the technical literature suggest that substances of the class of C1 fuels possess very favourable combustion characteristics, can be easily produced and have an acceptable energy density. A scientifically proven quantitative assessment of the potential of these fuels cannot be made at present as the relevant studies and field reports have not been adequately corroborated so as to allow an analysis of these technologies on the basis of their properties in practical applications. From a purely chemical perspective, all C1 molecules qualify as candidates for synthetic fuels, especially in areas where because of high required loads the battery would become excessively large and strict environmental standards relating to the avoidance of local pollutants by application of hydrocarbon fuels could only be complied with by means of very complex aftertreatment measures. Synthetic fuels are not competitors for electric mobility but are instead complementary. The plug-in hybrid constitutes an universal drive platform combining the battery-electric with synthetic fuels and using renewable energy from local areas with high surpluses which can be transported to the centres of high demand.