Improvements of CSP/Biomass Hybridisation with Single-Phase Fluids

Concentrated Solar Power techno-economic value has been proven due to the ability to dispatch energy with thermal energy storage integration. Though, additional technical and cost-effective solutions may result from the strategic combination with other energy sources (i.e. hybridisation), as in Shams 1 where CSP and natural gas are combined. Analogous improvements can be realised in a fully renewable system using biomass, yet with additional challenges. Despite the inherent advantages from the strategic combination of different renewable sources in the power generation portfolio, there is a need to evaluate the optimal design and integration. In this paper, specific biomass hybridisation improvements for CSP plants operating with single-phase heat transfer fluids, i.e. thermal oil and molten salts are evaluated. The assessment was carried out through numerical simulation, using a quasi-transient validated model, considering a 5MW(el) hybrid CSP/biomass plant. Hybrid plant performance was evaluated and compared with solar-only for distinct plant operation stages: start-up; cool-down; and steady-state with abundant solar radiation. Different hybridisation alternatives are considered: biomass boiler location; biomass conversion technology; and feedstock types. Hybridisation enhancements and specific design considerations are evaluated for each case. Results show that hybridisation improves the overall plant performance by assuring the power block to operation near design conditions. The use of biomass to boost up steam parameters outcome in a substantial power block efficiency enhancement, without jeopardising the solar field efficiency for thermal oil heat transfer fluid.