Generation Integrated Energy Storage - A Paradigm Shift

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

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Description The work on Generation-Integrated Energy Storage at Cambridge has, so far, focused on integration of thermal storage into nuclear power cycles. The basic philosophy is to devise storage methods that require minimum intervention into the nuclear plant and that are cheap compared to the default battery-like storage scenario. A journal paper has been written which focuses on storage linked to the so-called 'feed heating' system. Feed heating, which is used in nearly all steam power plant, is the process of bleeding steam form the turbines to pre-heat the water that goes into the boiler. It serves to significantly improve the efficiency with which heat from the fuel or nuclear reaction is converted to electricity. It also provides a very interesting and effective opportunity for storage: the 'charging up' process is achieved simply by bleeding more steam from the turbines (hence reducing their power output) and generating additional pre-heated feedwater (typically at about 230 deg. C) which can be stored. During discharge less steam is bled from the turbines (so the power output goes up and they generate excess electricity). This means that less pre-heated boiler feedwater can be produced, but the shortfall is made up by that which was previously stored. Meanwhile the nuclear reactor (the expensive part of the plant) continues to operate at its design, base load throughout. This potentially leads to a very cheap and efficient form of storage. Since the last submission a journal paper on this topic was submitted (to I.Mech.E ine early December 2022) and second paper focusing on off-design operation of the turbines and heat-exchange components is being prepared for the forthcoming Heat Powered Cycles Conference (Edinburgh, Sep. 2023).

A fascinating aspect of this storage method (and a theme common to other forms of GIES) is that during the charging process some of the "thermodynamic losses" that occur during normal operation of the power plant do not take place (essentially because some of the conversion of heat to electricity does not happen). So, the "available energy" going into storage is greater than the reduction in electricity output - as if the storage process itself had an efficiency greater than 100%. This could never happen for traditional, stand-alone electricity storage. Of course losses do occur later during the discharge process, but the overall "round-trip" efficiency can nonetheless be very high, especially compared to other forms of thermo-mechanical storage. These ideas are now being further pursued by exploiting industrial links.
Exploitation Route The concepts are being actively pursued via discussions with industry - especially the Rolls Royce team developing SMRs, which are particularly suited to the systems described in the Key Findings.
Sectors Energy
 
Description High performance Carnot Batteries based on hybrid cycles 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This was a talk presented at the second International Workshop on Carnot Batteries in September 2020 by Pau Farres Antunez. The main themes of the talk were (i) using Pumped Thermal Electricity Storage (PTES) in combination with Concentrating Solar Power plant in order to capitalise on the infrastructure that is required for both (a form of "Genreation-Integrated Energy Storage") and (ii) a novel combination of PTES and Liquid Air Energy Storage. The talk provoked several enthusiastic questions.
Year(s) Of Engagement Activity 2020
URL https://www.repository.cam.ac.uk/handle/1810/317076
 
Description Kalina Cycle Carnot Batteries 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact This presentation was given at the second International Workshop on Carnot Batteries in September 2020. It details how Kalina cycles could be used in Pumped Thermal Energy Storage, discussing working fluid choice and performance results from a cycle model.
Year(s) Of Engagement Activity 2020
URL https://www.repository.cam.ac.uk/handle/1810/316131
 
Description Kelvin Club Talk: 'Is Electricity Storage in Hot Water' 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Other audiences
Results and Impact This was a talk at the so-called Kelvin Club of Peterhouse (Cambridge) to a range of academics - principally scientists, but others too and some members of the public. The talk was aimed at emphasising the alternatives to battery storage, and highlighting the merits of generation-integrated technologies. The overall aim was 'raising awareness'.
Year(s) Of Engagement Activity 2020
 
Description Thermo-Mechanical and Generation-Integrated Energy Storage 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited talk delivered by Alexander White at the Third International Conference of the Skoltech Center for Energy Systems (October 12-13, 2017), Moscow.
Year(s) Of Engagement Activity 2017
URL http://crei.skoltech.ru/energysystems/research/skoltech-ces-international-conferences/
 
Description UK Energy Storage Presentation: 'Nuclear Options for Generation Integrated Energy Storage' 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Conference presentation with approximately 100 attendees followed by participation in panel discussion
Year(s) Of Engagement Activity 2019