18 October 2021
POLYPHEM project: The future of small-scale CSP plants


Autumn 2021

The POLYPHEM project aims at improving the flexibility and the performance of small-scale Concentrated Solar Power plants, thanks to a solar-driven micro gas-turbine technology. As a final result, the project is building a 60kW prototype plant with a thermal storage unit and will validate this innovative power cycle in a relevant environment at the Themis solar tower in Targassone.

The challenge for small-scale CSP Plants
The decentralized generation of power on-demand in remote areas at competitive cost is a major challenge of CSP to which POLYPHEM is all about. This project of small-scale solar tower proposes robust technologies of engines forming the combined cycle (micro gas-turbine and ORC), easy-handling heat transfer fluid (thermal oil) and cheap material for heat storage (concrete). One expectation of this challenging project is to demonstrate the reliability of the technology and the flexibility of the power generation from solar energy.

POLYPHEM: Small-Scale Solar Thermal Combined Cycle
Funded under Horizon 2020 (Energy programme), POLYPHEM is coordinated by CNRS-PROMES and brings together 9 partners from 4 EU countries. The project runs from April 2018 to March 2022 with a 4.975 M€ EC grant over these 4 years.

The main objective of the POLYPHEM project is to improve:

  • the performance of small-scale Concentrated Solar Power (CSP) plants
  • and their flexibility to generate power on demand

To this end, a new technology is proposed: a solar-driven combined cycle with integrated thermal energy storage.

The power block considered in POLYPHEM is a combined cycle intended to be used for decentralized small-scale power generation in the range 40 kW to 2000 kW in remote areas. The purpose is to meet the variable demand of energy of a minigrid. The baseline technology consists of an air Brayton cycle as top cycle and an Organic Rankine Cycle (ORC) as bottom cycle.

POLYPHEM broadens this technology by driving the top cycle with solar energy through the development of an advanced technology of pressurized air solar receiver and by including an innovative thermal energy storage unit between both cycles. Besides electricity generation, other applications will be considered for future developments.

Expected impacts and results
The outcomes of POLYPHEM will allow in the short term to reinforce the competitiveness of this new low carbon energy technology, to favour its integration in the medium term in the European energy mix and to contribute to the mitigation of climate change.

The main expected impact of this project is to enhance the competitiveness of low-carbon energy production systems through the technology developed. The expected progress is a better fitting of electricity generation to variable local needs, an overall conversion efficiency of solar energy into electricity of 18% for an investment cost of less than 5 €/W and a low environmental impact.

By 2030, the cost of electricity production targeted by the POLYPHEM technology is 165 €/MWh for an annual direct normal irradiation of 2600 kWh/m2/year (North Africa and Middle East) and 209 €/MWh under 2050 kWh/m2/year (Southern Europe).

In addition to decentralized power generation, other applications are considered for the deployment of this technology used in poly-generation: solar heating and cooling of multifamily buildings, water desalination for small communities, industrial heat production, desalination of seawater or brackish water, etc.


More information
Wesbite: https://www.polyphem-project.eu/

This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement N° 764048.