Project summary

Predictability and flexibility are key enablers to increase CSP penetration in the energy mix by:

  1. Increasing dispatchability
  2. Making CSP less/not reliant on subsidies
  3. Supporting stable grid operation
  4. Enabling operators to access new revenue streams (electricity trading, ancillary services).

Today CSP plants with molten salt storage only partly achieve these objectives. Key enabling technologies to be demonstrated and introduced in the market are:

  1. Design and operation of molten salt once-through steam generator – This will allow fully flexible plant operation
    an innovative design approach is proposed in PreFlexMS project, integrating process and equipment design with dynamic simulation of the system. Proven technologies in separate fields (molten salt; once-through steam generator; optimum control) will be for the first time integrated and demonstrated.
  2. design and implementation of integrated weather forecasting and dispatch optimization – This will allow optimal management of the energy storage to maximize revenues while respecting constraints/commitments (e.g. to the grid).
    different approaches to DNI forecasting (direct; mesoscale models) will be integrated in PreFlexMS project to extend geographical coverage and improve reliability. Dispatch optimization under conditions of uncertainty (weather forecast) and perturbations (e.g. grid support requests) will be developed.

Furthermore, automatic plant performance characterization by machine learning will be implemented to ensure a real optimum is achieved. For successful market introduction, a down-scale pilot will be realized. Here, integrated operation of once-through steam generator, weather forecast and dispatch optimization will be demonstrated. CSP will undergo large growth in developing markets, where grid constraints and market liberalization will play a role. Developing these key-enabling technologies will put European industries in the position to compete at the forefront in the market worldwide.

Predictability & flexibility

The proposed project name is “PreFlexMS”. This name stems from the key words “Predictability”, “Flexibility” and “Molten Salt”. In fact, this proposal 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.

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.

Enabling technology: Integrated Weather forecasting & Dispatch optimization:

Weather forecasting
  • Where technology stands
    • Mesoscale models, mostly for Europe and North America
    • Derivation of local GHI
  • What needs to be done
    • Improving accuracy of local prediction of DNI, temperature, cloud coverage and wind
      • E.g. Machine learning to account for local weather features/patterns
    • Extension of applicability to areas where limited weather and forecast data are available
      • E.g. Quantification of stochastic error
    • Specification of minimum data inputs and equipment
    • Specification of geographical areas of applicability
    • Real time forecasting for integration in plant control system
    • Demonstration
Dispatch optimization
  • Where technology stands
    • Many algorithms already developed
  • What needs to be done
    • Optimization under conditions of stochastic deviations and uncertainty
      • E.g.: Reaching a global optimum in the operator’s objective irrespective of uncertainties/stochastic deviations
    • Machine learning for implementation of algorithms in plant control systems
      • E.g. Algorithms sensing and learning the characteristics of the plant
    • Real time optimization and direct integration in plant control system
    • Integration with weather forecasting
    • Demonstration
Flexibility will be increased in terms of start-up time, load change rate, turn-down capability and part-load efficiency. Weather forecasting and dispatch optimization will allow plant operators to manage the energy stored in the molten salts to maximize the economic return from the plant operation.
Enabling technology: Molten Salts Once-Through Steam Generator (MS-OTSG):
  • High flexibility at different operating conditions
  • Suitability to frequent start-up/shut-down and load change
  • Fast start-up and fewer restrictions imposed on turbine start-up
  • Suitability for producing steam at high temperature and pressure
  • Decrease in water consumption
  • Opportunity for compact layout/component integration
  • Weight reduction compared to drum-type evaporator
Flexibility components
  • MS-OTSG – Where technology stands:
    • Once-through is proven technology for conventional CCPP
    • Never realized with Molten Salts
  • MS-OTSG – What needs to be done:
    • Design, optimize, integrate and demonstrate
    • Component design (materials, heat transfer)
    • System design (process, instrumentation, integration)
    • Arrangement (integration, drainage)
    • Operation & control concept (normal, emergency)
    • System cost optimization
    • System performance evaluation
    • Demonstrator