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A global transition to sustainable energy systems is underway, evident in the increasing proportion of renewables like solar and wind, which accounted for 12 % of global power generation in 2022. The shift to a low-carbon economy will likely require a substantial increase in energy storage in the near future. In this context, concentrating solar power (CSP) is viewed as a promising renewable energy source in the coming decades. However, high generation costs compared to other renewable technologies remain a key barrier inhibiting wider deployment of CSP. Compared to solar PV and onshore wind alternatives, CSP cannot currently compete on the levelized cost of electricity (LCoE). This review provides a comprehensive overview of the vital economic factors and considerations for large-scale CSP expansion. The current state of the market reveals about 8 GW of installed global CSP capacity in 2023, with rapid growth occurring in China, Chile, South Africa and the Middle East. Key economic parameters discussed in this study include capital costs, capacity factors, operating expenses and LCoE. Installation costs for CSP declined by 50 % over the past decade, falling to the current range of $3000–11000 per kW. Adding 6–15 h of thermal energy storage at $20–60 per kW is now considered economical. Capacity factors increased from 30 % to more than 50 % (depending on location) through larger storage capacities and higher operating temperatures. Operations and maintenance costs now range from $12–15 per kW-year. The resulting global weighted average LCoE for CSP plunged 68 % from $0.31 per kWh in 2010 to $0.10 per kWh in 2022. Ongoing innovations in materials, components integrated systems and optimization can further reduce capital expenditures, enhance performance and decrease LCoE. However, appropriate incentives and financing mechanisms remain vital to support continued CSP technology maturation and cost reductions. With its inherent dispatchability and storage capabilities, CSP can become a cost-competitive renewable energy source, but design optimizations and accurate economic appraisals are imperative for CSP to achieve its vast sustainability potential. • Global weighted average electricity capacity factors for CSP plants rose 66 % from 2011 to 2021. • Global weighted average LCoE for CSP fell 68 % from $0.31/kWh in 2010 to $0.10/kWh in 2022. • Capital costs for CSP fell 50 % in the last decade to $3000–11000/kW. • Adding 6–15 h of thermal storage at $20–60/kW is now considered economical. [ABSTRACT FROM AUTHOR]

Integration of thermal energy storage with concentrated solar power (CSP) plant aids in smoothing of the variable energy generation from renewable sources. Supercritical carbon dioxide (sCO 2) cycles can reduce the levelised cost of electricity of a CSP plant through its higher efficiency and compact footprint compared to steam-Rankine cycles. This study systematically integrates nine sCO 2 cycles including two novel configurations for CSP applications with a two-tank sensible heat storage system using a multi-objective optimisation. The performance of the sCO 2 cycles is benchmarked against the thermal performance requirement of an ideal power cycle to reduce the plant overnight capital cost. The impacts of the compressor inlet temperature (CIT) and maximum turbine inlet temperature (TIT) on the cycle selection criteria are discussed. The influence of the cost function uncertainty on the selection of the optimal cycle is analysed using Monte-Carlo simulation. One of the novel cycle configurations (C8) proposed can reduce the overnight capital cost by 10.8% in comparison to a recompression Brayton cycle (C3) for a CIT of 55 °C and TIT of 700 °C. This work describes design guidelines facilitating the development/selection of an optimal cycle for a CSP application integrated with two-tank thermal storage. • Optimisation of 9 sCO 2 cycles (2 novel) integrated with CSP and sensible heat TES. • Techno-economic evaluation of impact of heat addition temperature difference (ΔT). • Maximum cycle efficiency away from the optimal heat addition ΔT increases TES cost. • Increasing turbine inlet temperature from 600 to 700 °C increases overnight cost. • Novel cycle reduces the overnight capital cost by 10.8% over recompression cycle. [ABSTRACT FROM AUTHOR]

• Off-design Pareto fronts of sCO 2 cycle using multi-objective optimisation approach. • Storage capacity reduces by 25% at 55 °C compressor inlet temperature (design = 42 °C). • Off-design compressor inlet pressure estimation method to maximise efficiency. • Capacity factor increases by 10.8% when operating the plant in maximum power mode. • Number of start-ups reduce by about 50% when operating in maximum efficiency mode. Supercritical Carbon Dioxide (sCO 2) cycles can achieve higher efficiency compared to steam-Rankine or Air-Brayton cycles, therefore they are promising for concentrated solar power applications. Although sCO 2 cycles show higher design efficiency, the off-design efficiency is highly sensitive to the ambient conditions, impacting the power block net-power and heat input. In the present work a recompression sCO 2 cycle is connected to a central-tower solar field with two-tank thermal storage delivering molten chloride salt at 670 °C. The temperature of the molten-salt exiting from the power block and returning to the cold storage tank increases by 46 °C with respect to the design value when the compressor inlet temperature is raised by 13 °C relative to the design condition of 42 °C, which implies that the capacity of the thermal storage reduces by 25%. The main focus of this work is to investigate the off-design performance of a sCO 2 recompression cycle under variable ambient temperature, molten-salt inlet temperature and molten-salt flow rate. Multi-objective optimisation is carried-out in off-design conditions using an in-house code to explore the optimal operational strategies and the Pareto fronts were compared. Since the power cycle can either be operated in maximum power mode or maximum efficiency mode, this study compares these two operational strategies based on their annual performance. Results indicate that the capacity factor of the concentrated solar power can be increased by 10.8% when operating in maximum power mode whilst the number of start-ups is reduced by about 50% when operating in maximum efficiency mode. [ABSTRACT FROM AUTHOR]