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Uderground Pumped-Hydro Energy Storage Using Carbon Dioxide in Shallow Lined Rock Caverns; Application to Long-Duration Storage as The Energy Conversion of a Pumped Thermal Electricity Storage
P. Lalanne, P. Byrne
Storage, Heat Pump, pumped hydro, heat engine, Underground pumped hydro
PV Systems and Storage – Modelling, Design, Operation and Performance
Subtopic: Storage
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 5CV.3.58
1532 - 1542
ISBN: 3-936338-60-4
Paper DOI: 10.4229/EUPVSEC20192019-5CV.3.58
0,00 EUR
Document(s): paper


A fast-paced energy transition needs a better penetration of renewables, of heating and of cooling in the worldwide energy mix. With three novelties 1 – of using shallow high-pressure LRC (Lined Rock Cavern) excavated close to storage needs, 2 - of using a slow-moving CO2 piston applying constant pressure on the hydro part of UPHES (Underground Pumped Hydro Energy Storage) and 3 - of relying on inexpensive thermal stores for the longduration storage of electricity, CO2 UPHES coupled with PTES (Pumped Thermal Electricity Storage) could become a game-changer by allowing the complete integration of intermittent renewable sources. The RTE of the latter system, devoid of the 4 gas machineries of conventional PTES, is targeted to 60-70% and its Capex cost for pure electricity storage is calculated at 2160 USD/kW + 10 USD/kWh (meaning a compounded Capex of 20 USD/kWh only). Thanks to an attractive COP of heat displacement, expected to reach 10 depending on required temperatures, the CO2 UPHES as well as UPHES-PTES hybrid storage could also allow a low cost, low investment (compounded Capex of 4 USD/kWh) and low-emission integration of intermittent renewables with future district heating and cooling networks.