Progress in research and technological advancements of commercial concentrated solar power plants

The world’s energy system is undergoing major changes as we move towards a net-zero carbon economy. Indeed, the undeniable impact of greenhouse gas (GHG) emissions on the climate encourages countries around the world to progressively promote renewable energy technologies. However, due to intrinsic intermittency of renewable energies such as wind and solar photovoltaic, their large-scale introduction will pose a challenge for the stability of the power grid, as unexpected changes in local meteorology can significantly alter the production wind and solar PV power. Therefore introducing more variable renewable energy sources (VRES), namely wind and solar PV generation into the energy mix puts pressure on the power system. Concentrated solar power (CSP) is a technology offering a solution to this problem, because unlike conventional solar PV plants, CSP plants can incorporate thermal energy storage (TES) systems such as molten salt energy storage to allow them to generate electric power whenever it is needed – day and night, regardless of the weather conditions. This makes CSP a far more promising solution for large scale power generation from solar and therefore the most suitable technology to promote a massive penetration of solar energy in the power generation industry.

CSP technologies are among the most viable and promising renewable energy technologies that can be scaled up for a rapid transition towards high renewable energy utilization scenario (Calvet et al., 2021, Fang and Zhao, 2020, Giaconia et al., 2020, Laporte-Azcué et al., 2020, Liu et al., 2022, Martínez et al., 2020, Powell et al., 2017; W. Wang et al., 2021a, Wang, 2019). While the bulk of CSP electricity will come from large, on-grid power plants, these technologies also show significant potential for supplying specialized demands such as process heat for industry, co-generation of heating, cooling and power, and water desalination. CSP also holds potential for applications such as household cooking and small-scale manufacturing that are important for the developing world. The possibility of using CSP technologies to produce solar fuels (e.g. hydrogen and jet fuels), is another important aspect of CSP which strengthen its role in the low carbon economy. Moreover to mitigate the climate change, the IEA says that by the end of the century, CO₂ will need to be removed to keep temperature rise to under 2°. So, along with switching to renewable energy, we will need to remove carbon dioxide from the air. Heat is required to perform the thermochemistry involved in CO₂ air capture. As the heat-based form of solar energy, CSP is well positioned to play a key role in CO₂ removal, to begin to rebalance the earth’s atmospheric chemistry. It is expected that CSP, together with wind and solar photovoltaic, will constitute a stable, high percentage of renewable energy generation system that will be price-competitive with conventional energy sources (Agency, 2021, IRENA, A.D., 2014, Zhang et al., 2021).

However, the cost reductions achieved by rival technologies (mainly solar PV) force CSP developers to go further in the search of cost reductions due a highly competitive market and the lack of tariffs that correctly value the dispatchability of CSP. While CSP has been widely criticized for being expensive and often inefficient, the tables are now turning. Technology has improved significantly, costs are falling rapidly, and most importantly, environmental benefits are increasing. In fact, many governments around the world have made decisions to increase the use of solar thermal power over traditional fossil fuels such as coal. For example, this year (2022) four Chinese provinces have announced to build 24 CSP plants with a combined capacity of 2450 MW by 2024 (Kraemer, 2022a, Kraemer, 2022b, Kraemer, 2022c). Each of the planned projects includes at least 6 h of low cost thermal energy storage (most of them include ≥9 h). The current TES costs are low compared to storage in chemical batteries, which suggests a role for CSP with TES (i.e., CSP + TES) relative to PV+ batteries, due to favorable storage costs for TES despite the disadvantage in generation costs for CSP (Kennedy et al., 2022).