Synthetic energy sources will play an important role in replacing oil, natural gas and coal in the near future. Mostly produced from electrolytic hydrogen from renewable electricity and CO2, they will power airplanes and ships, serve as a raw material for the chemical industry or store energy. In a recent study for the Federal Environment Agency (UBA), ifeu, together with its project partners DLR and Joanneum Research, investigated whether the production of these synthetic energy sources harms the environment. The result: if done correctly, they can help to protect the climate, but there is a risk that the air, water and soil will become more polluted.
In most areas, the most efficient way to decarbonize is to use electricity from renewable energies directly. However, in some sectors of industry, such as aviation and international shipping, this is hardly technically possible. Power-to-X (PtX) energy carriers could meet this need in the future. These are synthetic gases (hydrogen, methane) or liquid hydrocarbons (diesel, petrol, kerosene, methanol) that can be produced using electricity from renewable sources.
The aim of the SYSEET project was to determine the environmental impact associated with the production of these storable energy sources - today and in the course of the transformation process up to 2050. To this end, over 60 paths for producing PtX energy sources and transporting them to Germany were analyzed. In this model, for example, diesel is produced using electricity from photovoltaic plants in Saudi Arabia and CO2 from cement plants there and transported to Germany by tanker. In another path, the production of methanol in Sweden from residual forest wood and with electricity from hydropower is analyzed. The production of hydrogen in Germany and the production of biomethane from agricultural raw materials were also considered. Overall, the pathways were selected in such a way that the influence of different process steps and options could be clearly identified. Finally, the environmental impact was analyzed in a computer-based life cycle assessment model.
The most important finding: PtX energy sources can save greenhouse gases, but even with 100 percent electricity from renewable sources, the production of synthetic fuels is associated with considerable environmental impacts.
