SUCCES (Stored Up-valued Concentrated Cold Energy System)

Energy storage is an essential technology for balancing the differences in supply and demand in a sustainable power network reliant on intermittent renewable generation. Energy can be stored as electricity, as heat and chemically in a sustainable fuel and at different temporal and size scales. Short time variations in the power grid can be effectively managed using batteries but the battery technologies are too expensive for servicing the bulk long term storage requirements to balance variations in demand between seasons and extended periods of low renewable generation. Technologies with a slower response, lower round trip efficiency but lower capital base are preferred for these applications. Liquid Air Energy Storage (LAES) is a long duration storage technology being developed by Highview Power. Energy is stored thermally in three ways; as cold in liquid air and in a backed bed regenerator cold store and as heat in a molten salt hot store. An air liquefier is used to charge the LARS device. LAES has a sweet spot at large (>50MW) scale as plant efficiency increases and relative cost reduces with scale for this technology. But what would happen if a LAES plant could be efficiently deployed at smaller (<50MW) scale? The technology could then be integrated with other aspects of the energy network that require cooling at cryogenic temperatures such as the long term storage of bio methane and green hydrogen. In this project, we will investigate the integration of a small to mid scale LAES plant with the liquefaction of locally produced bio methane from waste, such as agriculture, managed grass land (such as parks and sports fields) and sewerage. Similarly, hydrogen produced by small to mid size electrolysers connected to local renewable generators requires a storage solution. We propose cold, pressurised storage of hydrogen at 80-90K which lowers the pressure required to store the gas (for an equivalent energy density) by a factor of 2 to 3 and avoids the high energy cost of cryogenic storage at 20K.

Integration of LAES with methane and hydrogen storage opens up new revenue steams and shifts the economics to favour smaller plant serving local communities such as large farms, local authorities and water companies managing sewage waste. We propose a local rather than central solution as (a) the feedstocks for bio-methane production have a low energy density to local production and storage avoids transportation inefficiencies (b) Similarly local production and consumption of hydrogen avoids the need to move cold pressurised gas to bulk storage facilities and then to consumers and (c) imbedding the core electrical energy storage of the LAES plant closer to the end user has benefits in reducing the load on the transmission network.