AN ENVIRONMENTAL ASSESSMENT OF ENERGY STORAGE USING THE RESTORE CONCEPT: ANALYSIS OF THE GMUNDEN CEMENT PLANT

Abstract

The RESTORE initiative explores an innovative method of energy storage based on the thermochemical cycling of copper sulphate. During periods of surplus renewable electricity, such as for example solar-rich summer months, the system stores energy through the dehydration of copper sulphate. The stored energy is subsequently recovered during colder periods, such as winter, when energy demand increases and renewable availability declines, via the rehydration of the material. The current investigation focuses on the industrial RESTORE application at the Gmunden cement plant in Austria, proposing the integration of Thermochemical Energy Storage (TCES) with an Organic Rankine Cycle (ORC) and a Heat Pump (HP). The sustainability of the system was evaluated through a Life Cycle Assessment (LCA), conducted in accordance with the standard LCA framework, using version 10.8 of the LCA for Experts software. Environmental performance was quantified based on eleven key indicators derived from the ReCiPe 2016 assessment method. The functional unit for this study was set as the generation of 1 kWh of thermal energy, enabling a consistent comparison between the two construction alternatives of storage tanks, relevant to the industrial use case: carbon steel against high-density polyethylene (HDPE). The system boundaries were established to encompass the complete life cycle, segmented into three primary stages: i) Upstream activities; ii) Core operational processes; iii) Downstream operations. The use of HDPE outperformed carbon steel in key impact categories, cutting global warming potential (GWP) by over 55%, while significantly lowering other indicators. However, increased impacts in terms of fossil depletion and freshwater ecotoxicity potential are registered, likely due to the petroleum-based nature of HDPE. Several discussions and interpretations of the most relevant environmental key performance indicators are provided, underlining the effectiveness of the proposed concepts.