Battery Characterisation and Management - the key to Smart Grids and the Integration of Electric Vehicles

Lead Research Organisation: University of Southampton
Department Name: Faculty of Engineering & the Environment

Abstract

As recently as the 9th November 2012, the UK Chancellor, Mr George Osborne, stated in a speech to the Royal Society that "there is the challenge of storing more electricity for the Grid. Electricity demand peaks at around 60GW, whilst we have a grid capacity of around 80GW - but storage capacity of around just 3GW. Greater capability to store electricity is crucial for these power sources to be viable. It promises savings on UK energy spend of up to £10 billion a year by 2050 as extra capacity for peak load is less necessary." China, by contrast, has a grid capacity of over 1,000GW and an electrical demand growth rate of over 11% p.a, and in 2011 installed more wind capacity than the rest of the world put together. Concurrently, plans to clean up emissions from the transport sectors are leading to ambitious plans to expand the use of electric vehicles which will both challenge the electricity system due to the substantial need for battery charging, but also provide opportunity as these batteries can be used to provide energy storage.
Hence the challenge for both the UK and China is, recognising the current global EV market is forecast to grow from 1.7 million units in 2012 to 5.3 million units in 2020, how to utilise this massive aggregate electrical energy storage capacity from EV batteries to deliver essential power network services such as frequency support, load levelling, 'firming' of renewable generation and so forth. The dual use of such vehicle energy storage (to provide its core vehicle transportation duty and grid support when connected to the network for recharging) is referred to as Vehicle-to-Grid (V2G) operation. V2G has many technical challenges to overcome as well as requiring careful cost benefit analysis of the effect of increased charge/discharge cycling of the battery, and associated degradation, versus the grid support benefits achieved.
The dual use of EV batteries to provide grid support will make available very fast acting (<5 sec) and, crcially, low cost (Euro22/kW) aggregated energy storage, at cost levels significantly below dedicated grid battery installations (e.g. Euro3180/kW (@$1=Euro0.75) for the PGE 5MW, 1.25MWh Li-ion battery grid support project in Salem, Oregon, US) or competing energy storage technologies like compressed air energy storage (CAES).
Critically this proposal aims to focus on V2G operation from a battery perspective 'upwards' and not from a network level 'downwards', as the key factors relating to the success of V2G are those concerned with the battery technology. The research challenges identified with this work are:
1) Determining the anticipated patterns of battery cycling associated with driving and V2G operation for specified grid support functions e.g. frequency support, peak shaving etc.
2) Investigating the impact of the anticipated V2G operation on battery cell, module and pack cycle life, failures and thermal behaviour (i.e. thermal cycling and impact on cold/hot battery charging behaviour). Additionally more accurate determination of battery state of charge (SoC) and state of health (SoH) is required, including ensuring cell balance within the battery pack.
3) Investigating the communication and control temporal and physical information requirements from the battery management system (BMS) to the grid control system and vice versa.
4) Demonstrating V2G operation within distinct UK and Chinese environments, employing the new BMS software with cycling/thermal control, and improved SoC/SoH prediction.

Planned Impact

At the heart of this UK-China research collaboration is the aspiration to encourage a technological, societal and economic impact to help address the apparently conflicting transport and energy sectors. To reduce greenhouse gas emissions, the energy sector seeks to utilise more renewable energy, which is inherently less controllable, and to reduce energy consumption. Conversely the transport sector seeks to reduce tailpipe emissions through technical change from petroleum fuels to electric vehicles, which has the net result of increasing the load on the electricity network and potentially increasing the peak load, requiring more controllable generation plant to satisfy this load. This international research collaboration aims to address such global challenges by delivering the following impact across a range of stakeholders:

Industry - Enhanced understanding of EV Batteries, via improved cycle life and safety management;
Supporting EV initiatives of the China Assoc. of Automobile Manufacturers and UK Automotive Council, via use and demonstration
of improved batteries;
Stakeholder engagement via consortium workshop events;
Electric Utilities and Renewable sector through applicability of V2G, as the lowest cost form of grid scale electrical energy storage,
to support grid/renewables development

Government - Supports climate change policy for reducing transport emissions, and EV targets;
Assist convergence towards renewable targets enabled via V2G grid support;
Supports UK 'key' technology within energy storage sector

Society - Demonstration of EV functionality and improved EV battery knowledge;
Reduced greenhouse gas emissions via increased EV uptake and V2G support of renewables
 
Description Vehicle-to-Grid (V2G) is the aggregated use of the batteries on many electric vehicles (EVs) to provide a grid-scale energy store when these EVs are plugged into the grid. The key findings of this project are:
1) studies proved that V2G can provide Fast Frequency Response (FFR) to provide electricity grid frequency responce, thereby helping grid stability and operation;
2) V2G can be delivered via use of EV car parks (i.e. centralised rather than geographical distributed EVs);
3) a hardware prototype V2G interface between the grid and EV has been developed based on a neutral point clamped (NPC) multi-level converter and tested;
4) improved EV battery management system (BMS) state of charge (SoC) and state of health (SoH) predictions and monitors have been developed showing improved performance and accuracy based on extended Kalman Filters (EKF);
5) Simulation of large V2G systems have been improved via:
a) use of Markov Chain Monte Carlo techniques to generate critical vehicle usage patterns, which are essentail for electricity network planning;
b) online description of Matlab based V2G simulator tool;
6) an electrochemical based capacity fade (degradation) model of lithium ion batteries has been produced and reported;
7) the network impact and cost of EV charging has been simulated, with and without V2G, to highlight the network benefits and reduced EV charging costs that are potentially available. This work also highlighted the critical impact of the battery degradation cost assumptions on the economic viability of V2G.
8) an online V2G public enagagement tool that will help 'sell' the concept of V2G to the public and other users.
Exploitation Route Electricity system operators, electricity aggregators and EV users will be interested in both the holistic V2G studies undertaken as well as specific elements of this work e.g. V2G interface, improved BMS models and battery capacity fade models. The field of V2G is currently being actively pursued and trialled via industrial and academic parties e.g. the recent KTN V2G Scoping Workshop in Feb 2017, and such interested parties will clearly be informed and could utilise the outcomes of this project.
The academic and research partners in this work are all currently pursuing further activities in the field of V2G, which will continue to build upon this project.
Sectors Digital/Communication/Information Technologies (including Software),Energy,Environment,Transport

URL http://www.southampton.ac.uk/v2g
 
Description The output of this project continues to inform ongoing work in both industry and academia, into improve lifetime assessment of Li-ion batteries, the possibility of grid-scale energy storage using Vehicle-to-Grid (V2G) and enhanced battery management systems. An exhibit featuring electric vehicles with V2G operation is being created and will be exhibited at the Winchester Science Centre, to help inform and educate the public and interested parties about the capabilities and potential of V2G, and also of the trajectory of the interface between the electricity and transport sectors based around V2G and EV operation.
First Year Of Impact 2017
Sector Education,Electronics,Energy,Transport
Impact Types Societal

 
Description Centre for Doctoral Training in Energy Storage and its Applications
Amount £4,078,783 (GBP)
Funding ID EP/L016818/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 04/2014 
End 09/2022
 
Description ELEVATE (ELEctrochemical Vehicle Advanced TEchnology)
Amount £574,078 (GBP)
Funding ID EP/M009394/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 11/2014 
End 10/2018
 
Description SUPERGEN Energy Storage Hub
Amount £225,000 (GBP)
Funding ID EP/L019469/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 06/2014 
End 06/2019
 
Description TransEnergy - Road to Rail Energy Exchange (R2REE)
Amount £1,520,000 (GBP)
Funding ID EP/N022289/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 08/2016 
End 07/2019
 
Description 'Electric Cars' Science Exhibit 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact An exhibit, entitled 'Electric Cars', exploring the grid use of vehicle-to-grid (V2G) technology, was developed jointly by the University of Southampton and Winchester Science Centre as part of this EPSRC grant, and was exhibited both at the Winchester Science Centre (from July 2018 - present) and the Manchester Science and Industry Museum, Power Playground event, held as part of the Electricity Festival, 20th/21st September 2018.
Year(s) Of Engagement Activity 2018
 
Description Press Interview on Vehicle2G 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact A telephone interview with Mark Hillsdon, from The Guardian, July 2015, for an article on the Guardian's ENEL sponsored micro-site regarding Vehicle-to-Grid (V2G).
Year(s) Of Engagement Activity 2015
 
Description Southampton University Science Week 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Exhibit sparked discussion about merits and challenges of electric vehicles, principally centered around the performance of the batteries.

After this event we received a number (~10) enquiries regarding our work and the electric vehicle we exhibited.
Year(s) Of Engagement Activity 2014
URL http://www.southampton.ac.uk/schoolsandcolleges/scienceweek/scienceday.html
 
Description V2GCity at Universities Week 2014, Natural History Museum, London 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Exhibit generated significant interest in electric vehicles and energy storage.

A number of schools requested details of the V2GCity web address.
Year(s) Of Engagement Activity 2014
URL http://www.southampton.ac.uk/per/university/roadshow.page
 
Description V2GCity exhibit at the Cheltenham Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Exhibit sparked enquiries regarding our work on using electric vehicles as an aggregate, large scale energy store.

Had follow-on dialogue about energy storage with representatives from IBM and EdF.
Year(s) Of Engagement Activity 2014
URL http://www.southampton.ac.uk/per/university/roadshow.page