Storage and Cross-linked Infrastructures (SCI)

Research Highlights 2019

Highlight 1: Topic 2 - SOEC stack operated with a solar furnace
At DLR, a commercial high-temperature electrolysis stack (SOEC) was successfully coupled with a solar simulator for the first time worldwide. Using a high-power radiator from the DLR solar simulator and a solar receiver, hot water vapour was generated and fed into a SOEC stack consisting of 12 layers. Thus the experimental coupling of high-temperature steam electrolysis and solar thermal steam generation could be demonstrated in principle. By means of suitable control and regulation, stable current-voltage characteristics could be achieved with the stack at an output of 1.65 kW. In further experiments, the coupling of solar heat into the co-electrolysis process of steam and CO2 is to be tested, which in the long term will enable an environmentally friendly production of synthetic fuels.

Highlight 2 KIT
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Highlight 2: Topic 3 & Topic 4 - Co-Electrolysis and e-fuels study
KIT scientists have succeeded in the experimental proof-of-concept for the production of synthetic fuel (eFuel) from air CO2 and water via coupled process steps of CO2 Direct Air Capture, co-electrolysis of CO2 and water vapor, Fischer-Tropsch synthesis, and hydrocracking with about 10 liters per day in container format (press release 2019_107).  By internal use of the energy and material flows of all process steps an overall efficiency of 60% was determined for perspectively larger plants. Since commissioning, more than 100 litres of eFuel have already been produced. The project team celebrated this success with invited guests from industry, politics and the press on 6.11.2019 as part of the Kopernikus Project "P2X", which is sponsored by the BMBF. The fuels were investigated together with industrial partner Audi (DLR) and accompanied by a road mapping process for eFuels. A comprehensive analysis of the synthesis processes for hydrogen and CO2-based eFuels was carried out at FZJ. The eFuels were compared in terms of energy demand, yield, efficiency, emissions and capital and operating costs. PEM water electrolysis was used for H2 production. H2 costs of 4.6 €/kg were determined and adopted in comprehensive apron system studies. The costs for methanol, ethanol, dimethyl ether, Fischer-Tropsch middle distillate and methanol-to-gasoline turn out to be particularly favourable in a range of 1.85 - 2.30 € per litre diesel equivalent. 

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Highlight 3: Topic 5 - TESIS - Liquid salt storage with temperature stratification
With the test facility for heat storage in molten salt (TESIS), the world's largest functional verification of new types of single-tank storage concepts for liquid salt storage tanks was achieved during the period under review. With a storage capacity of 4 MWh in the temperature range 290-560 °C, the maintenance of a stable temperature change zone in the storage tank for 9 full cycles was successfully demonstrated experimentally. The temporal course of the temperature change zone was determined experimentally and by interpolation with about 150 temperature measuring points. The determined behaviour shows a good agreement with previously prepared simulation results. Further single-tank concepts are to be investigated, because favourable fillers such as rock promise a cost reduction potential of up to 40 % compared to the two-tank liquid salt storage according to the state of the art.

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Highlight 4: Topic 6 - HTS modeling
In the EU project "Advanced Superconducting Motor Experimental Demonstrator", a fully superconducting demonstrator for a motor is to be developed for the first time in the world that meets the requirements for high power density and fast speed for future electric drives of aircraft. Within the scope of the project, KIT has succeeded in directly coupling the calculation of the electromagnetic behavior of the rotating machine with the calculation of the AC losses in the individual windings. Thus, superconducting rotating machines can now be calculated more efficiently and accurately in the future. The demonstrator currently under construction will finally validate the calculations.