Vergleich einer statischen und dynamischen Ökobilanzierung eines Hybridregelkraftwerks unter Berücksichtigung verschiedener Betriebsstrategien

Kurzfassung

With the increase of generation-output-varying renewable energies in the energy supply system, the development of flexibilities to ensure their integration while keeping the balance of generation and consumption in the electricity grid is essential. The HyReK, a hybrid regulating power station characterised by the combination of a stationary BESS with a PtH-plant, is capable of providing balancing power in the form of frequency control reserve (FCR) and thus contributing to the stability of the grid frequency of the interconnected grid. Within the scope of this work, a life cycle assessment (LCA) of the HyReK is carried out according to DIN EN ISO 14040:2009 and DIN EN ISO 14044:2006 using the LCIA methodology ReCiPe 2016 in order to identify the environmental impacts caused by the HyReK during its production and operation phase. The cradle to gate analysis was based on the functional unit of one MWh of storage capacity. Taking the operating phase into account, the funcional unit of one MWh of FCR provided is considered. The work is characterised both by a high Proportion of primary data used and by its approach: the system boundaries include not only the BESS itself but also the infrastructure necessary for the operation of the system ("balance of system"), which distinguishes it from other studies. The battery cells of the BESS with the cathode, anode and electricity demand for their production were identified as hotspots having the biggest overall environmental impacts. Regarding the operation phase, it was shown, that the operating losses were most relevant for environmental impacts, which were mainly caused by the idle losses of the inverter system due to the oversized system capacity and their resulting low utilisation. The dynamic LCA (DLCA) was implemented in order to identify changes of the environmental impacts when taking into account the temporal variations for comparing different operational strategies. By using a developed approach, the most environmentally relevant process of the operating Phase (operating losses of the plant) was dynamised. This enabled an evaluation of two operating strategies (aiming at a SOC of 70 and 90 %) on the basis of two scenarios (all inverters active (Scenario uniform) and switching off inverters that are not required (Scenario minloss)) and a subsequent economic classification of these. Furthermore, these were evaluated in a subsequent economic classification in the form of an economic efficiency calculation. The work shows that the currently pursued operating strategy is ecologically and economically preferable to the second strategy investigated. Differences in the comparison of the static and dynamic LCA did not occur due to the selected time horizon, which was limited to one year and the lack of detailed data on the future weekly composition of the electricity mix. However, based on this study, recommendations for an optimised implementation of future studies could be made. The sensitivity analysis and examination of the scenarios showed that environmental impacts during the production and operation phases can be greatly reduced by applying technical measures like switching off unrequired inverters. Likewise, further research as well as the development towards an electricity supply with a higher share of RE can lead to the reduction of environmental impacts. Future research potential lies in focusing on the environmental and economic optimisation of the operational strategy. It would also be suitable to carry out a more comprehensive DLCA including the dynamisation of the overall system and an impact assessment method. Furthermore, the consideration of the end-of-life-phase is being recommended.