Storing Liquid Air and Thermal Energy for Long-Duration Energy Storage

Project Overview

Long-duration energy storage (LDES) will be a key enabler for increased use of renewable and clean energy. Adiabatic, liquid air energy storage (A-LAES), which has advanced to the commercialization stage, is promising due to its efficiency and compact footprint. We investigate the feasibility of improving the efficiency and storage duration of A-LAES by using stored heat recuperated from the power-turbine exhaust, combined with at least one of (1) stored heat created by electrical furnaces, (2) direct heat from the combustion of hydrogen (H2), created by electrolysis, or (3) direct heat from the combustion of agricultural and forest waste biomass. We consider oxy-combustion of biomass because it produces pure CO2, which can be immediately dehydrated, compressed, and sent to either a user or geological sequestration, thereby adding the benefit of negative CO2 emissions.

We find round-trip efficiency can be improved from 65% for A-LAES to 83% when the turbine-inlet temperature is boosted from 220 oC to 1000 oC. The addition of electrical-furnace heat is very efficient. At 500 oC, every joule used to create heat returns an extra 0.94 joules of electricity. At 1000 oC, every joule used to create heat returns an extra 0.99 joules of electricity. The use of granular beds to store electrified heat may provide tens of hours of storage duration, while the use of biomass and H2 in combustion furnaces may provide months of storage duration. LLNL's approach is scalable, with the potential of buffering more than 100% of electricity consumption in California and across the U.S., allowing greatly expanded use of renewable and clean electricity.

Mission Impact

This study is a first step to develop, demonstrate, and deploy a LDES technology to meet the challenges of affordable, clean, carbon-free energy, delivered within a sustainable infrastructure and providing power grid reliability and resiliency, which supports Lawrence Livermore National Laboratory's Climate and Energy Security and Multi-Domain Deterrence mission areas. This work may lead to synergistic, cross-cutting pathways for delivering clean electricity from facilities that enable negative CO2 emissions and for delivering carbon-free electricity from regional clean H2 hubs.