Potential values of Scotland's legacy mines in renewable energy integration by 2035

Flooded legacy mines across Scotland provide great opportunities for thermal energy storage (TES) due to their large water storage and natural insulators of rock masses. They can not only act as controllable electricity demand by importing otherwise curtailed renewables to heat up water, but also supply carbon-free heating sources extracted from the hot water to local households, business and public buildings when needed. To offer insights into the values of Scotland’s legacy mines in facilitating the integration of renewable generation, the paper evaluates the TES capacities of the legacy mines located in Scotland’s Central Belt and reviews the electricity system development in the Great Britain (GB) by 2035. Then, a zonal network representing multiple regions of Scotland and the rest of GB is modelled by aggregating generation, demand and energy storage capacities within each zone. The schedules of network components are daily updated by a dynamic DC optimal power flow that optimises the operation of battery energy storage, pumped hydro storage and interconnectors for a maximum use of renewable generation. The resulting renewable curtailment under 2035 scenarios is compared with TES capacities of legacy mines to understand their comparability in scale.