Energy storage
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Solution Overview
Problem
Cryogenic energy storage systems, such as Liquid Air Energy Storage (LAES), face limitations in instantaneous response and heat loss due to thermal storage, which affect their efficiency and ability to balance electrical grids with fluctuating renewable energy sources.
Innovation Solution
A cryogenic energy storage system incorporating a liquefaction apparatus, cryogenic storage tank, power recovery apparatus, and a charging apparatus with a hot thermal store, where thermal energy is transferred to the power recovery apparatus to enhance energy output and include a load bank or heating device for instantaneous thermal energy supply, allowing for fast frequency response and balancing grid demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If thermal storage is used to store heat produced by compressors, then energy recovery is improved, but heat egress causes thermal energy loss over time
Solution Approach 1:
The patent replaces the mechanical/thermal insulation approach with an active refrigeration system. A refrigeration cycle is implemented where a refrigerant circulates between evaporator and condenser to actively remove heat from the thermal storage tank, counteracting heat egress and maintaining thermal energy over extended storage durations.
Solution Approach 2:
The patent changes the thermal parameters of the storage system by introducing a refrigeration cycle that actively controls temperature. The refrigeration system maintains the thermal storage tank at lower temperatures to minimize heat egress to the environment, thereby reducing thermal energy loss during storage.
2Speed
If LAES systems use mechanical components like turbo-expanders and compressors, then power recovery is achieved, but response time is delayed by several minutes
Solution Approach 1:
The patent makes the refrigeration system multi-functional by using it for both cooling the thermal storage tank (reducing heat egress) and providing rapid power response. The refrigeration cycle can be quickly activated or deactivated to provide instantaneous power response while maintaining thermal energy storage, thus achieving both fast response and power recovery.
3Quantity of substance
If surplus electricity is used to liquefy gas during low demand periods, then energy storage capacity is built, but system complexity increases
Solution Approach 1:
The refrigeration system serves multiple functions: it cools the thermal storage tank to reduce heat egress, enables cryogen liquefaction during charging, and provides rapid power response during discharge. This multi-functionality reduces the need for separate dedicated systems, thereby managing complexity while achieving cryogen storage capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides improved instantaneous response and reduced heat loss, enabling faster frequency response and better balancing of electrical grids by modulating thermal energy supply to match renewable energy fluctuations, enhancing the overall efficiency and utility of LAES systems.
Implementation Method 1
utilise low cost or surplus electricity, at periods of low demand or excess supply from intermittent renewable generators, to liquefy a working fluid such as air or nitrogen during a first liquefaction phase
Implementation Method 2
LAES systems often include thermal storage to store the heat produced by the compressors used in the refrigeration cycle required to charge the system. This heat is then used to superheat the working fluid (i.e. cryogen) during the power recovery phase
Implementation Method 3
subsequently released to drive a turbine, producing electricity during a discharge, or power recovery, phase
Data Source
AI summary
A cryogenic energy storage system comprising a liquefaction apparatus for liquefying a gas to form a cryogen, wherein the liquefaction apparatus is controllable to draw power from an external power source to liquefy the gas, a cryogenic storage tank in fluid communication with the liquefaction apparatus for storing cryogen produced by the liquefaction apparatus, a power recovery apparatus in fluid communication with the cryogenic storage tank for recovering power from cryogen from the cryogenic storage tank by heating the cryogen to form a gas and expanding said gas, a hot thermal store for storing hot thermal energy, wherein the hot thermal store and the power recovery apparatus are arranged so that hot thermal energy from the hot thermal store can be transferred to the gas before and/or during expansion in the power recovery apparatus, and a charging apparatus which is controllable to draw power from the external power source when the power drawn by the liquefaction apparatus is below a threshold value, and supply the cryogenic energy storage system with thermal energy.