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Planned decommissioning of coal-fired plants in Europe requires innovative technical and economic strategies to support coal regions on their path towards a climate-resilient future. The repurposing of open pit mines into hybrid pumped hydro power storage (HPHS) of excess energy from the electric grid, and renewable sources will contribute to the EU Green Deal, increase the economic value, stabilize the regional job market and contribute to the EU energy supply security. This study aims to present a preliminary phase of a geospatial workflow used to evaluate land suitability by implementing a multi-criteria decision making (MCDM) technique with an advanced geographic information system (GIS) in the context of an interdisciplinary feasibility study on HPHS in the Kardia lignite open pit mine (Western Macedonia, Greece). The introduced geospatial analysis is based on the utilization of the constraints and ranking criteria within the boundaries of the abandoned mine regarding specific topographic and proximity criteria. The applied criteria were selected from the literature, while for their weights, the experts' judgement was introduced by implementing the analytic hierarchy process (AHP), in the framework of the ATLANTIS research program. According to the results, seven regions were recognized as suitable, with a potential energy storage capacity from 1.09 to 5.16 GWh. Particularly, the present study's results reveal that 9.27% (212,884 m 2 ) of the area had a very low suitability, 15.83% (363,599 m 2 ) had a low suitability, 23.99% (550,998 m 2 ) had a moderate suitability, 24.99% (573,813 m 2 ) had a high suitability, and 25.92% (595,125 m 2 ) had a very high suitability for the construction of the upper reservoir. The proposed semi-automatic geospatial workflow introduces an innovative tool that can be applied to open pit mines globally to identify the optimum design for an HPHS system depending on the existing lower reservoir.

Archimedes screws have become increasingly popular throughout Europe to drive hydropower plants using residual flow from a stream or river. This heightened usage of such screws during the past few years is attributable to their robustness, simplicity, and fish friendliness. Presently the dimensioning of a hydropower site equipped with an Archimedes screw is dependent mainly on the experience of the design engineer. This is so because there is no appropriate theory for the optimal hydraulic design of screws used at hydropower sites, especially for the water-inflow conditions. In this paper, a new analytical model for the water inflow is derived, and the optimal values of the inflow parameters are determined to achieve a planned inflow to the screw. [ABSTRACT FROM AUTHOR]