Optimal offering strategy of virtual power plant with hybrid renewable ocean energy portfolio

This paper proposes a hybrid ocean energy system to form a virtual power plant (VPP) for participating in electricity markets in order to promote the renewable ocean energy utilization and accommodation. In the proposed system, solar thermal energy is integrated with the closed-cycle ocean thermal energy conversion (OTEC) to boost the temperature difference between surface and deep seawater for efficiency and flexibility improvements, and the thermodynamic effects of seawater mass flow rates on the output of solar-boosted OTEC (SOTEC) are exploited for deploying SOTEC as a renewable dispatchable unit. An optimal tidal-storage operation model is also developed to make use of the subsea pumped storage (SPS) with hydrostatic pressures at ocean depth for mitigating the intermittent tidal range energy in order to make the arbitrage in the electricity market. Furthermore, a two-stage coordinated scheduling strategy is presented to optimally control seawater mass flow rates of SOTEC and hydraulic reversible pump-turbines of SPS for enhancing the daily VPP profit. Comparative studies have been investigated to confirm the superiority of the developed methodology in various renewable ocean energy and electricity market price scenarios.