Periodic Reporting for period 2 - SOLARSCO2OL (SOLAR based sCO2 Operating Low-cost plants)
Reporting period: 2022-04-01 to 2024-07-31
According to the JRC CSP platform, with an increased efficiency of component and price reduction, it could be feasible that 11 % of EU electricity will be produced by solar thermal electricity by 2050. In the EC energy strategy, CSP is mentioned as a potential dispatchable RES with increasing potential market/need when coupled with flexible, high performant and low CAPEX power conversion units. In this respect, sCO2 has been studied for several years as a future technology to overcome steam-based cycle in efficiency and power density - and thus as enabling technology to promote CSP widespread all over the world. SOLARSCO2OL presents sCO2 cycles as a key enabling technology to facilitate a larger deployment of CSP in the EU panorama, which is today composed (also considering available surfaces and DNI) by medium temperature application (most of them Parabolic trough – Tmax = 550°C) and small to medium size plants (all of them of 50 MW or less - as described in §2.1) enhancing their performance (efficiency, flexibility, annual yield) and reducing their LCOE. Considering that compared to organic and superheated steam-based Rankine cycles, sCO2 cycles achieve high efficiencies over a wide temperature range (thus giving the opportunity to couple sCO2 power blocks with molten salt CSP plants, existing and newly built), with lower CAPEX, lower OPEX, no use of water as operating fluid (a plus for CSP plants in arid locations), smaller system footprint, and higher operational flexibility, SOLARSCO2OL aims to demonstrate the first MW Scale EU sCO2 power block operating in a real CSP plant. SOLARSCO2OL will strengthen EU Leadership in CSP industry also capitalizing previous EU expertise (SCARABEUS, sCO2-flex, MUSTEC), bridging the gap with US , China , Japan R&D on these topics and studying different power plant layouts also to enhance CSP plants flexibility to enable providing grid flexibility services. SOLARSCO2OL is indeed not a just a H2020 demonstration project but the first sCO2 MW scale demo installed and tested in a real CSP plant environment worldwide (TRL8).
In the second reporting period, the layout, schematics, and operating modes of the SOLARSCO2OL system were defined, including the thermodynamic cycle and preliminary P&ID. The pre-design layout was established, with KPIs and cost models identified for techno-economic optimization. Components like the heat exchangers (HEXs) and electric heater progressed through design, analysis, and manufacturing, with testing scheduled for the upcoming months. The definition of the demonstration plan at the Évora Molten Salt Plant platform (EMSP) reached an advanced stage, with detailed engineering, design finalized and procurement ongoing. The design of the compressor and turbine was finalized, with auxiliary systems defined and integrated into the power block, targeting >35% efficiency at low scale and >38% at medium-high scale. A plant model and preliminary control logic were developed using MATLAB/Simulink. Dynamic simulations and off-design analysis were carried out to optimize plant performance under different load conditions. Simplifications in the model were introduced for real-time predictive control applications. Environmental and economic assessment models were developed, evaluating different design alternatives and their environmental impacts. Key components were compared with benchmarks to guide upscale efforts in future project phases. A social assessment focused on stakeholder feedback was initiated, with CERTH leading efforts to gauge the acceptability and social impact of SOLARSCO2OL solutions. Upscaling scenarios for both the EU and extra-EU markets were analyzed, targeting CSP plants. Feasibility studies were conducted for the integration of SOLARSCO2OL technologies with existing CSP infrastructure, with MASEN examining potential replication in the NOOR III Tower plant in Morocco. The project disseminated findings through journal articles, conference papers, webinars, and international events. These efforts engaged CSP industry stakeholders, turbomachinery OEMs, and energy professionals, raising awareness of the project's innovations. A stakeholder map was developed to classify those interested in integrating sCO2 technology into CSP plants. This engagement is ongoing, with plans to publish a positioning paper and organize an EU final event.
SOLARSCO2OL will reduce CSP plants LCOE operating with MS based on an innovative sCO2 power block that could be applied to any CSP plant independently from the type and size. In particular the project aims to reach the following KPIs: -10% of CAPEX reduction, reduction of LCOE up to 10c€/kWh, +10% of plant efficiency thanks to the improvement in the single turbomachinery efficiency, -90% CO2eq considering the HC/CO emission reduction related to avoided use of auxiliary boilers that would not be needed anymore thanks to sCO2 power block lower operating temperature and MS electric heater integration. In the second reporting period, a comparative analysis of hybrid PV-CSP-sCO2 configurations against traditional CSP and PV systems demonstrated significant LCOE reductions. For 10 MWe plants, the PV-EH-TES-sCO2 configuration was the most cost-effective below 60% capacity factor, while hybrid CSP-sCO2 trough systems were optimal above this threshold. In larger 100 MWe systems, hybrid PV-CSP-sCO2 tower configurations proved the most economical for baseload generation above 65% capacity factor. These results underscore the potential of SOLARSCO2OL technology to drive cost savings, particularly in smaller, modular CSP systems, enhancing dispatchability and economic viability. Techno-economic studies suggest that SOLARSCO2OL could reduce LCOE by up to 58% compared to current CSP-only systems, especially in smaller-scale applications. The project aims to accelerate renewable energy adoption, improving efficiency and reducing emissions, which could generate job growth and contribute to climate goals. High-efficiency sCO2 turbomachinery will be developed, supported by an advanced grid-oriented control system for enhanced flexibility. In SOLARSCO2OL high efficient turbomachinery components will be developed, making them compatible to work with sCO2 and able to deal with intermittent/variable solar input. The integration of the different components will be ensured by a grid oriented advanced control system, based on dynamic modelling of the different components. The control logics will allow a predictive control of the system, enhancing the flexibility and operability of the plant. The environmental and social acceptability of SOLARSCO2OL plant are ongoing and studied via LCC/LCA/s-LCA methods, ensuring the social viability of sCO2 and CSP plants and promoting for the first time sCO2 as the best operating fluid in turbomachinery for the future EU RES Based scenario, thanks to sCO2 higher efficiency, lower capex, lower operating temperature, which make sCO2 perfect to be coupled with a large variety of systems. The replication of SOLARSCO2OL layout will be then studied both in EU and extra EU countries, ensuring the developing of suitable business models to promote the replication of the concept in current and future CSP plants.
Finally a strong Dissemination and communication strategy will ensure the soundness of SOLARSCO2OL results, proposing the project with relevant stakeholders and presenting it in multiple events.
Finally a strong Dissemination and communication strategy will ensure the soundness of SOLARSCO2OL results, proposing the project with relevant stakeholders and presenting it in multiple events.