Periodic Reporting for period 2 - SCARABEUS (Supercritical CARbon dioxide/Alternative fluids Blends for Efficiency Upgrade of Solar power plants)
Periodo di rendicontazione: 2020-04-01 al 2021-09-30
The Levelized Cost of Electricity (LCoE) of CSP (currently about 150 €/MWh ) has not attained the level targeted (100 €/MWh) except for few installations in exceptionally good locations. Many ongoing research projects aiming at enhancing the efficiency of the power block and reducing the associated costs are based on supercritical CO2 technology. However, relatively high ambient temperatures, typical in regions characterized by high solar irradiation, penalize the sCO2 cycle efficiency. SCARABEUS proposes a modified working fluid whereby carbon dioxide is blended with certain additives to enable condensation at temperatures as high as 60°C whilst, at the same time, still withstanding the required peak cycle temperatures. The adoption of blenbded CO2 increases the thermomechanical conversion efficiency from the current 42% to above 50%, bringing about large reductions in LCoE.
The aim of the SCARABEUS project is to demonstrate that the application of supercritical CO2 blends to CSP plants has the potential to reduce CAPEX by 30% and OPEX by 35% with respect to state-of-the-art steam cycles, thus exceeding the reduction achievable with standard supercritical CO2 technology. This translates into a LCoE lower than 96 €/MWh, which is 30% lower than currently possible. The project will demonstrate the innovative fluid and newly developed heat-exchangers at a relevant scale (300 kWth) for 300 h in a CSP-like operating environment.
The aim of the SCARABEUS project is to demonstrate that the application of supercritical CO2 blends to CSP plants has the potential to reduce CAPEX by 30% and OPEX by 35% with respect to state-of-the-art steam cycles, thus exceeding the reduction achievable with standard supercritical CO2 technology. This translates into a LCoE lower than 96 €/MWh, which is 30% lower than currently possible. The project will demonstrate the innovative fluid and newly developed heat-exchangers at a relevant scale (300 kWth) for 300 h in a CSP-like operating environment.
In the first year, the following activities have been performed;
i) an innovative cycle concept was identified with a thermal efficiency above 51% assuming a maximum temperature of 700°C;
ii) The effect of CO2 blends on turbomachinery design was assessed with turbine efficiency up to 93.0%;
iii) An innovative S-shaped fins where developed reducing the plat surface by 8% with respect to conventional fins;
iv) Preliminay LifeCycle Assessment showed that SCARABEUS technology has a carbon footprint below 24 kgCO2/MWh;
v) The design of the test-rig is finalized and equipment supply as started.
i) an innovative cycle concept was identified with a thermal efficiency above 51% assuming a maximum temperature of 700°C;
ii) The effect of CO2 blends on turbomachinery design was assessed with turbine efficiency up to 93.0%;
iii) An innovative S-shaped fins where developed reducing the plat surface by 8% with respect to conventional fins;
iv) Preliminay LifeCycle Assessment showed that SCARABEUS technology has a carbon footprint below 24 kgCO2/MWh;
v) The design of the test-rig is finalized and equipment supply as started.
CAPEX will be reduced: sCO2 blends bring about smaller turbomachinery components, reduced heat exchanger area and less complexity, all of which is foreseen to reduce the cost of the power block by 40% with respect to conventional steam cycle technology and 30% with respect to standard sCO2 cycles. And most importantly, the higher efficiency (for the same boundary conditions) should reduce the costs of the solar field and tower by 20%. The resulting CAPEX is estimated at 3500 €/kWel which is 30% less than the current cost;
OPEX will be reduced: the higher efficiency brings about a 15% OPEX reduction which adds up to another 15% reduction coming from the adoption of dry cooling and a simpler power block. The final OPEX, which includes both fixed (€/MW) and variable (€/MWh) terms, will be 12 €/MWh which is 60% of the current value of 20 €/MWh;
EU energy security will be improved: The proposed concept targets a solar Concentrated Solar Power plant where electricity is produced from solar energy only (pure solar electricity), hence contributing to the diversification of energy sources in Europe.
Affordable and integrated energy storage solutions will be developed: SCARABEUS has a large impact on the design and cost of the thermal energy storage (TES) system which is included in the reference CSP plant. The new working fluid (CO2-blend) allows for a significant reduction of the inventory of heat transfer fluid in the TES system thanks to the much higher efficiency of the power block (lower thermal energy reserve for the same storage of equivalent-electricity)
Technology performance will be increased: The adoption of SCARABEUS in solar tower plants will yield higher conversion effiencies than commercial technologies both at design and off-design operating conditions. The expected design efficiency is >50% compared to 47% for sCO2 Cycles and 43% for steam power plants, and this advantage is confirmed also at part load;
Innovation capacity will be improved: The key enabling innovation in SCARABEUS is a new working fluid (blended CO2) used in the power block. Along with this, a second significant innovation is the development of innovative (from a conceptual standpoint) air-cooled condenser and recuperative heat exchanger designs which will be optimized for each particular working fluid and demonstrated experimentally.
OPEX will be reduced: the higher efficiency brings about a 15% OPEX reduction which adds up to another 15% reduction coming from the adoption of dry cooling and a simpler power block. The final OPEX, which includes both fixed (€/MW) and variable (€/MWh) terms, will be 12 €/MWh which is 60% of the current value of 20 €/MWh;
EU energy security will be improved: The proposed concept targets a solar Concentrated Solar Power plant where electricity is produced from solar energy only (pure solar electricity), hence contributing to the diversification of energy sources in Europe.
Affordable and integrated energy storage solutions will be developed: SCARABEUS has a large impact on the design and cost of the thermal energy storage (TES) system which is included in the reference CSP plant. The new working fluid (CO2-blend) allows for a significant reduction of the inventory of heat transfer fluid in the TES system thanks to the much higher efficiency of the power block (lower thermal energy reserve for the same storage of equivalent-electricity)
Technology performance will be increased: The adoption of SCARABEUS in solar tower plants will yield higher conversion effiencies than commercial technologies both at design and off-design operating conditions. The expected design efficiency is >50% compared to 47% for sCO2 Cycles and 43% for steam power plants, and this advantage is confirmed also at part load;
Innovation capacity will be improved: The key enabling innovation in SCARABEUS is a new working fluid (blended CO2) used in the power block. Along with this, a second significant innovation is the development of innovative (from a conceptual standpoint) air-cooled condenser and recuperative heat exchanger designs which will be optimized for each particular working fluid and demonstrated experimentally.