Apparatus and Method for Storing Energy

Abstract

In an energy storage and recovery system, working fluid from a first vessel is compressed by power machinery and passes, via a regenerator, into a second vessel, where it is forced to condense, the temperature and pressure of the saturated working liquid/vapour mixture continuously rising during storage. The stored energy is recovered by the vapour returning through the regenerator and power machinery where it expands to produce work before condensing back into the first vessel. The regenerator comprises a gas permeable, solid thermal storage medium which, during storage, stores superheat and some latent heat from the vapour passing through it in respective downstream regions that exhibit continuously increasing temperature profiles during storage and a small temperature difference with the surrounding vapour, thereby minimising irreversible losses during the thermal energy transfers.

Description

FIELD OF THE INVENTION[0001]This invention relates to a system and method for storing and recovering energy, especially for storing and recovering energy using thermal storage.BACKGROUND TO THE INVENTION[0002]The inflexibility in power generation provided by nuclear, solar and wind based renewable energy sources has posed a number of problems in using these technologies to provide a major part of a national or regional power grid. One such problem is the need to store and recover electrical energy to prevent disruptions to the electricity supply in the light of the variable energy supply, with particular issues being the cost of energy storage, the flexibility and the energy densities achievable. A number of energy storage technologies are now being developed to address such issues including pumped hydro storage, flywheel storage, compressed air energy storage CAES (including isothermal and adiabatic CAES) and pumped heat energy storage, as in accordance with Applicant's earlier app...

AI Technical Summary

Benefits of technology

[0034]TL1 will naturally decrease progressively with charging over time and increase progressively with discharging over time, unless steps are taken e.g. to add external heat or thermal ballast. A marching temperature is desirable on the LP side and HP side during condensation and vaporisation for a more reversible and hence efficient system. As mentioned earlier, thermal ballast will reduce the rate of marching on either side, if required. External heat from an auxiliary system added during charging may also reduce the rate of marching, or, on the LP side, totally eliminate any marching. The system may therefore be configured such that TL1 of L1 is maintained substantially constant for some or all of the storage mode, and / or for some or all of the recovery mode. In that case, there is little advantage to providing a regenerator disposed between the power machinery and the liquid stored in the first vessel.

[0035]The LP side vessel may be connected to a supply tank (e.g. infinite supply) that feeds in and out working fluid (e.g. continuously) such that some can be replaced with working fluid at a different temperature; this involves mass exchange and temperature exchange with the surroundings and may be used to reduce or eliminate marching of the L1 temperature and pressure.

Problems solved by technology

The inflexibility in power generation provided by nuclear, solar and wind based renewable energy sources has posed a number of problems in using these technologies to provide a major part of a national or regional power grid.

One such problem is the need to store and recover electrical energy to prevent disruptions to the electricity supply in the light of the variable energy supply, with particular issues being the cost of energy storage, the flexibility and the energy densities achievable.

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