Techno-economic and operational assessment of a solar-assisted hybrid liquid air energy storage under off-design conditions
Navia, Nafisa Tabassum (2026)
Diplomityö
2026
School of Energy Systems, Sähkötekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe20260731114210
https://urn.fi/URN:NBN:fi-fe20260731114210
Tiivistelmä
This thesis aims to develop an hourly full-year simulation of a solar-assisted hybrid LAES system and compare it with a standalone base under Finnish operating conditions. The hybrid model couples a LAES core plant which has evacuated tube solar thermal collector field and thermal energy storage buffer. An annual operating profile is constructed using PVGIS typical meteorological year for Vaasa, Finland and 2023 Finnish day-ahead electricity prices. The price thresholds of charging and discharging are considered as optimisation variables and identified through an exhaustive discrete search that maximises the annual electricity-arbitrage operating margin. Applying the same strategy to both configurations, the effect of solar integration is isolated. A techno-economic assessment is also carried out along with sensitivity analysis.
Maximising the annual arbitrage operating margin at approximately EUR 126,200, optimal thresholds identified were 40 EUR/MWh for charging and 80 EUR/MWh for discharging. Following these thresholds, solar-assistance increases the annual discharged electricity by 16.7% and raised the apparent electricity-to-electricity round-trip efficiency from 52.5% to 67.0%, by extending the number of hours the system could discharge at its rated output rather than by raising that output above the nominal plant rating. Electricity price timing is the main determinant of discharge timing in the present model and this is apparent in there occurring 172 hybrid-assisted discharge hours during October-March, compared to 145 during April-September. Both configurations yielded in negative net present value over 30-year, while the standalone being close to breaking even on a simple payback and hybrid configuration's operational improvements not offsetting its additional capital expenditure. Overall, the results pointed out that solar-thermal hybridisation has the potential to improve the operational performance of LAES even being in high-latitude and seasonally constrained solar condition.
Maximising the annual arbitrage operating margin at approximately EUR 126,200, optimal thresholds identified were 40 EUR/MWh for charging and 80 EUR/MWh for discharging. Following these thresholds, solar-assistance increases the annual discharged electricity by 16.7% and raised the apparent electricity-to-electricity round-trip efficiency from 52.5% to 67.0%, by extending the number of hours the system could discharge at its rated output rather than by raising that output above the nominal plant rating. Electricity price timing is the main determinant of discharge timing in the present model and this is apparent in there occurring 172 hybrid-assisted discharge hours during October-March, compared to 145 during April-September. Both configurations yielded in negative net present value over 30-year, while the standalone being close to breaking even on a simple payback and hybrid configuration's operational improvements not offsetting its additional capital expenditure. Overall, the results pointed out that solar-thermal hybridisation has the potential to improve the operational performance of LAES even being in high-latitude and seasonally constrained solar condition.