Flexible nuclear plants with thermal energy storage and secondary power cycles: Virtual power plant integration in a UK energy system case study

Electricity markets are fast changing because of the increasing penetration intermittent renewable generation, leading to a growing need for flexible operation power plants provide regulation services grid. Previous studies have suggested that conventional (e.g., nuclear) may benefit from integration thermal energy storage (TES), as this enables greater flexibility. In Rankine-cycle plants, steam can be extracted during off-peak periods charge TES tanks filled with phase-change materials (PCMs); at later time, when is required and/or economically favourable, these feed secondary generate power, example, by acting evaporators organic Rankine cycle (ORC) plants. This solution offers flexibility than TES-only solutions store and then release back base plant, it allows both derating over-generation. The applied here specific case study 670 MWel nuclear plant in UK, which typical baseload not intended operation. It found maximum combined 822 delivered peak demand, 23% higher plant's (nominal) rated 40%, i.e., down 406 demand. An operational management strategy (EMS) proposed optimising charging demand controlling discharging electricity generation peak-demand periods. economic analysis performed evaluate potential benefits EMS. Profitability considered result average price variations least double those occurred UK market 2019 (with recent data now close this), charge/discharge cycles more once per day discharge duration ORC longer 2 h. When considering most prices 2021 (to-date), EMS investment cost one 1-h 199 m£ total 50 GWh year levelised (LCOE) 463 £/MWh. drops significantly 48 8 h size decrease. projected LCOE also decreases 159 £/MWh doubling generated (100 GWh/year) employing two 8-h day. Importantly, economics determined trade-off between durations minimises their cost, shorter yield highest spread prices.