Technical and economic assessment of thermal energy storage in concentrated solar power plants within a spot electricity market

A techno-economic assessment of a 100 MWe concentrated solar power (CSP) plant with 8 h thermal energy storage (TES) capacity is presented, in order to evaluate the costs and performance of different storage configurations when integrating the CSP plant electricity into a spot market. Five different models were considered: a two-tank direct sensible heat storage (SHS), a two-tank indirect SHS, a single-tank thermocline heat storage, a latent heat storage (LHS) and thermochemical heat storage. The net present value (NPV) was selected as the most relevant metric that accounts the variability of prices over time. The system model advisor (SAM) software along with thermodynamic principles were used to obtain technical parameters. Excluding the solar field, power block and other cost contributions, the thermocline tank was the most profitable storage configuration with a higher financial profit of about USD 16 Million and USD 39 Million compared to the LHS and direct SHS respectively. The indirect SHS (USD -150 Million) and thermochemical heat storage (USD -253 Million) however presented the highest capital costs and consequently unprofitable investments. This paper provides reliable information to policy-makers and industrialists about the viability of the different TES technologies, and also helps the production optimization based on a price-driven strategy.