System comparison of storable energy carriers from renewable energies

Abstract

In the course of the transformation to a greenhouse gas neutral society in the second half of the 21st century, the use of synthetic energy carriers based on renewable electricity or biomass is discussed. This project evaluates the environmental impacts of technical and logistical options for the provision of such energy carriers based on environmental impact categories such as global warming potential, acidification or land requirements. Based on selected process steps/procedures and their current and future technical data, the production of five products (Fischer-Tropsch fuels, methanol, synthetic natural gas, biomethane, and hydrogen) was considered. The availability of renewable energy sources such as wind or PV, of raw materials such as carbon or water, and of transport routes to Germany formed the location factors for Germany, Europe and the Mediterranean region, by means of which the processes were combined into supply pathways for these energy carriers. The life cycle assessment method was used to analyze the environmental effects today and in 2050, and to estimate costs for plant construction and operation. According to the results, synthetic energy sources generally have a significantly lower global warming potential than today's fossil reference products due to the use of renewable energies. However, the manufacture of the power generation plants and associated economic processes - such as steel and cement production - can make a relevant contribution to the global warming potential if they are not also greenhouse-neutral. At the same time, especially the production of the required plants lead to (sometimes significantly) increased impacts in almost all other impact categories compared to the fossil reference, especially in water and land requirements. This study thus also provides indications as to which environmental impacts must be further reduced in the future.