Key points


In a Concentrated Solar Power Plant (CSP), a field of heliostats reflects and concentrates sunlight onto a receiver placed atop a tower. A molten salt (sodium-and potassium-nitrate) is heated up in the receiver and stored in large ground tanks. When electricity is to be produced, the hot salt is used to generate steam, which drives a steam turbine and electrical generator, supplying power to the grid.


Some large power plants (100+ MW) of this type are today in commissioning, construction or planning phase. They will be operated at constant load and produce electricity until the storage lasts into the night. They are economically viable because incentive schemes offered by regulators compensate for high initial costs and for limited operational flexibility.


The evolution of the CSP market will see regulators gradually phasing out subsidies. Additionally, grid operators expect from CSP stable, responsive, reliable and committed power supply, equivalent to gas power plants. Under these circumstances, CSP plant operators need flexible and reliable plants to adapt operation to market conditions and maximize their revenues.

PreFlexMS project aims at demonstrating and introducing into the market key enabling technologies to improve predictability and flexibility of a CSP plant with molten salt energy storage.


PreFlexMS will integrate improved weather and solar radiation forecast with electricity dispatch optimization. This will allow optimal operation to maximize revenues while respecting plant constraints and power supply commitments.


PreFlexMS will design a molten salt “once-through” steam generator (OTSG) allowing fully flexible operation with fast load changes, while bringing system simplification and cost reduction. In a new design approach, dynamic simulations will verify performance and suggest adjustments early in the development.


CSP plants require large up-front capital expenditures, which make investors wary of unproven technologies. To guarantee market uptake, PreFlexMS will build a pilot OTSG with integrated forecast and dispatch optimizer. The demo plant will be hosted at the Evora Molten Salt Platform in Portugal.

The PreFlexMS solution allows a significant increase in predictability through targeted weather forecasting and the development of new commercial weather services by European companies and institutions.


PreFlexMS is investing more than 18 M€ over 3 years (2015-2018) to develop technologies that will make CSP plants predictable and flexible. The value of the pilot installation in Portugal will exceed 7 M€.


CSP will reach 11 GW installed capacity by 2020 and 26 GW by 2030*, with large growth in developing markets, where grid constraints and market liberalization will play a role. PreFlexMS will make technologies for predictability and flexibility ready for the market and put European industry in the position to compete worldwide.

*IEA, World Energy Outlook 2014, “Current policy” scenario