Presentation on theme: "1 N. Keith Tovey, M.A. PhD, C.Eng MICE Н.К.Тови М.А., д-р технических наук Energy Science Director Low Carbon Innovation Centre University of East Anglia,"— Presentation transcript:
1 N. Keith Tovey, M.A. PhD, C.Eng MICE Н.К.Тови М.А., д-р технических наук Energy Science Director Low Carbon Innovation Centre University of East Anglia, Norwich The changing face of the Electricity Market in the UK Изменяющееся лицо рынка электроэнергии в Британии Руководитель по энергетическим исследованиям Центр экологических инноваций Университет Восточной Англии, Норвич Regulation in Electricity Supply CLIMATE CHANGE GOVERNANCE AND COMPLIANCE NBS-M
2 Course WEB Page or
3 A brief review of the UK Electricity Industry prior to 1990 under State Ownership. –differences in approach between England / Wales and Scotland. Fuels used for generation Fuel Diversity – The Shannon-Wiener Index The Electricity Markets in the 1990s after Privatisation The New Electricity Trading Arrangements NETA (2001) The British Electricity Trading and Transmission Arrangements (BETTA). The Supply of Electricity since 1990 Conclusions The changing face of the Electricity Market in the UK Изменяющееся лицо рынка электроэнергии в Британии
4 The Generation and Distribution of Electricity has always been different in Scotland compared to England and Wales (Шотландия всегда отличалась от Англии и Уэльса в плане производства и распределения э/э ) Scotland Шотландия Scotland (Шотландия): Two vertically integrated companies supplying discrete areas (Две вертикально интегрированных компании, снабжающие отдельные территории) England and Wales Англия и Уэльс England and Wales (Англия и Уэльс): One Generating Company (CEGB) and 12 Regional Electricity Suppliers (Одна генерирующая компания (CEGB) и 12 региональных поставщиков). EdF Electricité de France EDF 2000 MW Northern Ireland Северная Ирландия
5 Scottish Hydro Scottish Power Northern Yorkshire Eastern London East Midlands SEEBOARD SWEB Southern NORWEB MANWEB Midlands SWALEC Scotland Шотландия England & Wales Англия и Уэльс Structure of Electricity Supply in early 1990s Структура системы энергоснабжения в начале 1990 г.г. Scotland Шотландия Vertical Integration Вертикальная интеграция two companies две компании England and Wales Англия и Уэльс 12 Regional Supply Companies 12 региональных компаний also Distributed Network Operators а также распределяющие сетевые операторы
6 Electricity Generation in the UK Производство электроэнергии в Великобритании Until 2006, growth averaged 1.8% over previous 20 years In recent years gas has overtaken coal as dominant fuel and nuclear has declined Coal + Oil Nuclear Gas (CCGT) Renewables
7 Implications of daily/weekly/monthly variations in fuel use for Electricity Generation The carbon factor for electricity generation in UK is ~ 540g/kWh Varies from Hour to hour Day to day Week to week Month to month See Current accounting only uses Grid annual average. In future accounting may relate to emissions associated with time of use Thus a heavy industry with high electricity demand in day time could significantly reduce its carbon emissions by operating overnight rather than during day.
Daily fuel mix in electricity Generation 11 th January 2010
Weekly fuel mix in electricity Generation th January 2010 Mon Tues Wed Thurs Fri Sat Sun Notice higher proportion of coal used during day time hence a higher carbon emission factor.
The Shannon-Weiner Index (H) is defined as: H = - p I ln p I where p i is the proportion of the i th fuel. The index value increases with number of items and also the relative proportions of items 10 Shannon – Wiener Index of Fuel Mix Diversity With three fuels, the maximum value reaches 1.09 when all the fuels are in equal proportions. In Norway where Hydro provides 99.5%, the index for the three fuels used is just
Shannon – Wiener Index of Fuel Mix Diversity Shannon – Wiener Index is a measure of diversity originally developed as a measure of biodiversity. Higher index values occur with higher diversity. But there is no absolute upper limit. There is a maximum diversity index for a given number of fuels (e.g. species, fuels) when all items are in same proportion, but index will be higher for a greater number items. Index is low if one item dominates 11 Variation in maximum value of Index with number of items. The situation occurs when all items have equal proportion. e.g. with 6 fuel types the maximum value of index would be 1.8.
12 Shannon – Wiener Index of Fuel Mix Diversity Exercise Selected link for EXCEL Spreadsheet Template
13 Transmission Network in the UK Transmission throughout England, Wales and Scotland became unified on April 1 st kV 275 kV 132 kV Historically transmission networks have been different in England and Wales compared to Scotland Исторически, сети передачи э/энергии в Англии и Уэльсе отличались от сетей Шотландии Scotland Шотландия England and Wales Англия и Уэльс
Generating Capacity Surplus/Deficit on February 12th 18:00 +ve: generating capacity exceeding demand -ve: demand exceeding generating capacity Most Generating Capacity is in the North - most demand is in South MW Interconnector to Scotland Interconnector to France
15 Decision on how electricity was to be generated was done on a generating set basis Generating Sets to run were selected on Merit Order. Based on Marginal Costs (i.e. the fuel costs - цены на нефть) Some generating sets were run OUT of MERIT ORDER where system constraints were an issue. Generators sold electricity to Regional Electricity Boards Electricity Boards sold to consumers in their Area only Prices to consumers varied between regions Electricity Generation - pre 1990
16 Central Electricity Generating Board Центральное 12 Regional Electricity Companies Coal (Угольные) Fired Power Stations Oil (Нефтяные) Fired Power stations Gas Turbine (Газовы турбины) Stations Hydro Stations (ГЭС) Nuclear Stations (Атомные) Transmission (Трансмиссия) National Power PowerGen Nuclear Electric National Grid Company 12 Regional Electricity Companies Privatisation of Electricity Supply Industry 1990
17 Typical UK Electricity Demand in Winter 2003 and 2005
18 Comparison of Demand Forecast and Outcome Data for 48 hour period covering 27 th and 28 th September 2008 Note: there was an alert on 28 th from period 45 (i.e. 22:30) meaning no actual data is available from this time.
Obtaining Information from BMREPORTS Total Demand for electricity on a half hour basis may be accessed from: 19 INDO: Initial Demand Out- turn ITSDO: Initial Transmission Demand Out-turn – includes transmission losses etc What is todays demand: What are todays wholesale prices?
20 A brief review of the UK Electricity Industry prior to The Electricity Markets in the 1990s after Privatisation –the first system know as the Pool. –Some Countries operate a derivative of the Pool Operation of the Pool – the bidding Process The New Electricity Trading Arrangements NETA (2001) The British Electricity Trading and Transmission Arrangements (BETTA). The Supply of Electricity since 1990 Conclusions The changing face of the Electricity Market in the UK
21 Eastern ** Industry- Промышленность Independents- Независимые Electricité de France InnogyNuclear Electric *BNFL (Magnox)PowerGen RECs Licensed Suppliers Лицензирова нные поставщики Consumers Потребители Second Tier Consumers Вторичные потребители The Pool Пул Scottish Nuclear (Атомная) * Consumers Потребители Scottish Hydro Scottish Power Scotland Шотландия England and Wales Англия и Уэльс
22 Only the Generators (>100 MW) bid into the POOL to supply electricity e.g. National Power (now Innogy), PowerGen etc The National Grid Company published projected demands for the following day and invited bids The Generators supplied bids for each generating set in each station for each half-hour period of the following day The NGC sorted bids to determine which generating sets would be used for each particular period, and which ones would have capacity made available The Operation of The Electricity Pool: 1990 – 2001
23 Bid from company B £19.31 per MWh Bid from company A £19.20 per MWh (0.96R / kWh) Bid from company D £19.40 per MWh Bid from company E £19.50 per MWh Bid from company C £19.32 per MWh Range of bids from companies in range £18 - £19 per MWh Roubles per kWh Range of bids from companies in range £15 - £18 per MWh Roubles per kWh Range of bids from companies in range <£15 per MWh 0.75 Roubles per kWh MW 1250 MW MW System Marginal Price = £19.31 SMP Companies up to and including B successful £1 ~ 50 Roubles
24 All Companies who were successful were paid the SMP for all units generated irrespective of what their bid was The bids were for the single half-hour period and fresh bids were required for all half hour periods It was possible for companies to bid £0 and this would guarantee that they generated and paid SMP –However, if all Companies did the same they would have to generate electricity for nothing In addition to the SMP, there was also a capacity charge relating to the generating capacity which was requested to be available The Operation of The Electricity Pool
25 Capacity Charge paid to all Generators who had been requested to have capacity available. -based on formula(по формуле): LOLP * (VOLL - SMP) Loss of Load Probability The Operation of The Electricity Pool VOLL: was set by the Regulator at around £2400 per MWH LOLP: normally a very low figure but could become significant if there was a shortfall in generating Capacity Charge: signal to ensure sufficient capacity was available. Pool Input Price (PIP) = SMP + LOLP * (VOLL - SMP) Value of Lost Load
26 Some Power Stations constrained ON to ensure security of supply even when their bid was more expensive (Некоторые электростанции constrained ON обеспечить снабжение, даже в случае более дорогих заявок) Some Power Stations constrained OFF even when their bid was cheaper (-excess of capacity in one region) (Некоторые электростанции constrained OFF обеспечить снабжение, даже в случае более дешевых заявок) Constrained Stations paid their Bid Price (уплачивали их «заявочную» цену) POOL Output Price: (POP) = Pool Input Price + Uplift Uplift represented the additional charges incurred to National Grid Company because of System Constraints Suppliers purchased Electricity at Pool Output Price (Поставщики закупают э/э на Пуле по цене производителя) Электрический пул System Constraints (Система давления):
27 Электрический пул: A Review Need for strong Regulatory Body to ensure prices were not fixed. Evidence suggested price manipulation took place in early years. Regulator required major generators to dispose of some stations. The lack of Demand Side Bidding was a weakness Charges for Transmission Losses were averaged over whole Network. Customers in North subsidised those in South Generators in South subsidised those in North These issues have been partly resolved under BETTA Separate discussions relating to Distribution Charges are also under way
28 Changes in Regional Electricity Companies in the 1990s Mergers Scottish Hydro & Southern become Scottish & Southern Take-over Scottish Power takes over MANWEB Vertical Integration nPower acquire Midlands PowerGen acquire East Midlands United Utilities formed –in NORWEB area PowerGen nPower United Utilities Scottish & Southern Scottish Power Scottish Power 1990 c. 1998
29 The New Electricity Trading Arrangements NETA (2001) The British Electricity Trading and Transmission Arrangements (BETTA). –BETTA essentially extended NETA to cover Scotland. –There were few changes in England and Wales apart from Transmission issues –Operation of the Trading Market remained the same –Although minor modification take place all the time In BETTA Both Generating and Demand Side Bidding Takes Place Most Electricity is traded outside Balancing Mechanism Favours those who guarantee specific levels of generation/supply in advance Favours those who can guarantee flexibility in output / demand at short notice. The changing face of the Electricity Market in the UK
30 The basic principles Основные принципы Operation of BETTA Generators and Suppliers are penalised if they deviate from their agreed level of generation / supply. System security is maintained via the Balancing Mechanism Renewable Generators e.g. Wind and small CHP (~10 MW) can be adversely affected. Generation and Supply focuses on: Balancing Mechanism (BM) Units Generating BM Units: Demand BM Units Trading between Generating and Demand BM Units – Only the volume traded ( not price) has to be notified.
31 NETA/ BETTA The Balancing Mechanism: A Summary Day Before Current Day IPNFPN Gate Closure Real Time 30 mins 3.5 hours 1 hour Operation of Balancing Mechanism Changes to contract position cannot be made after Gate Closure Balancing Mechanism provides System Security Initial Physical Notification (IPN) – 24 hours in advance System Operator checks sufficient capacity is available. Final Physical Notification (FPN) Gate Closure for Real Time Period of 30 mins Initially 3.5 hours before REAL Time later reduced to 1 hour.
32 Generators and suppliers are penalised if they deviate from their contract position at the final physical notification (FPN). The System Operator negotiates with balancing Mechanism (BM) units to increase/decrease the amount of electricity available to maintain system security and ensure system remains stable. NETA/ BETTA: Operation of the The Balancing Mechanism: Case 1: Too little electricity on the system – Generators can OFFER to INCREASE output – Suppliers can OFFER to REDUCE consumption Time FPN OFFER Time FPN OFFER If OFFER is agreed then Generators / Suppliers are PAID for any electricity increased / reduced under the OFFER. Separate charges apply for these services.
33 The Balancing Mechanism Балансирующий механизм The New Electricity Trading Arrangements Новая система оптовой торговли НЕТА To allow system to remain stable Too little electricity on the system – Generators can OFFER to INCREASE output – Suppliers can OFFER to REDUCE consumption Time FPN OFFER Time FPN OFFER If OFFER is agreed then Generators / Suppliers are PAID for any electricity increased / reduced under the OFFER.
34 Case 2: Too much electricity on the system The New Electricity Trading Arrangements – Generators can BID to REDUCE output – Suppliers can BID to INCREASE consumption If BID is agreed then Generators / Suppliers PAY for any reduction in generation / increase in demand under the BID. Time FPN OFFER Bid FPN OFFER Bid Time
35 The Balancing Mechanism: Offers and Bids Generators / Suppliers may submit OFFERs or BIDs which differ for different levels of deviation from the Final Physical Notification National Grid Company normally accepts OFFERS / BIDS which are cheapest unless System Constraints prevent this MW: £30 per MWh (1.5 Roubles per kWh) MW: £50 per MWh (2.5 Roubles per kWh) MW: £20 per MWh (1 Rouble per kWh) FPN окончательная физическая нотификация Example of Differential Offers from a Generator
36 What happens if System Operator has got it wrong? OFFERs / BIDs cannot be cancelled UNDO BID removes an OFFER and is usually less than the OFFER UNDO OFFER removes a BID and is usually more than the BID OFFERs / UNDO BIDs [ or BIDs / UNDO OFFERs] are submitted in pairs OFFER / UNDO BID: Pair +2 OFFER / UNDO BID: Pair +1BID / UNDO OFFER: Pair -1BID / UNDO OFFER: Pair -2 FPN The Balancing Mechanism: Undo Offers/Undo Bids
37 FPN Paid SSP FPN Actual Metered Volume Pays SBP Charges for imbalance depend on whether BM unit is deviating in same direction as overall system or not. Example shows cases where imbalance is in same direction as system Установлено в двустороннем порядке договаривающ имися сторонами Settled bilaterally between contracting parties Установлено в двустороннем порядке между сторонами Settled bilaterally between parties Actual Metered Volume The Balancing Mechanism: Imbalance Charges
38 Regional Supply Ownership Distributed Network Ownership in 2004 Scottish & Southern nPower E.ON (PowerGen) Electricité de France Distributed Network Ownership Владение распределите льной сети Distributed Network Ownership in 2005 In 2007, Scottish Power became part of Iberdrola Scottish & Southern United Utilities CE Electric UK Western Power PowerGen Aquila Central Networks Western Power IberdrolaScottish Power Electricité de France Iberdrola Scottish Power UKPower Networks Distributed Network Ownership in 2010/11
39 Changes when BETTA came into force – April 1 st 2005 Integrated Trading System operating England and Wales with Scotland Before BETTA –System and Transmission Network Operator in England and Wales was National Grid Company (NGC). –System and Transmission Network Operator in South of Scotland was Scottish Power –System and Transmission Network Operator in North of Scotland was Scottish and Southern After BETTA –National Grid Company become System Operator for whole of England, Wales and Scotland. –NGC now Transmission operator for England and Wales –In Scotland the two companies now hold the respective transmission Network Licences –Issues of differences in Transmission Protocol had to be resolved – including the use of the Inter connector –Charges for Transmission Losses had to be addressed
40 Example of System Sell Price (SSP) and System Buy Price (SBP) corresponding with First Point of Triad Impact on System Sell and Buy Prices Sunday 6 th December 2010 Monday 7 th December 2010
41 How well has it performed since starting on 27th March 2001? Wholesale prices rose rapidly in 2004/2005, fell sharply from mid 2006, rose rapidly since mid 2007 then fell but are less stable. 41 UK becomes net importer of gas Completion of Langeled Gas Line to Norway Oil reaches $140 a barrel Impact on Wholesale Charges
B £20 to £25 per kW G - £5 to £0 per kW H - £10 to -£5 per kW Generator Connection Charges under BETTA Плата за подключение к генератору энергоснабжения по BETTA 18 F £0 to £5 per kW A > £25 per kW D £10 to £15 per kW C £15 to £20 per kW E £5 to £10 per kW
43 No.Zone NameTariff (£/kW) 1 North Scotland East Aberdeenshire Western Highlands Skye and Lochalsh Eastern Grampian and Tayside Central Grampian Argyll The Trossachs Stirlingshire and Fife South West Scotland Lothian and Borders Solway and Cheviot North East England North Lancashire and The Lakes Generation Connection Charges from April 1 st 2013 Note: Updated Values on those in handout and current as of October 2013 These are general charges for each area in addition there are additional charges reflecting the capabilities of the local regions around each substation
44 No.Zone NameTariff (£/kW) 15 South Lancashire, Yorkshire and Humber North Midlands and North Wales South Lincolnshire and North Norfolk Mid Wales and The Midlands Anglesey and Snowdon Pembrokeshire South Wales Cotswold Central London Essex and Kent Oxfordshire, Surrey and Sussex Somerset and Wessex West Devon and Cornwall Generation Connection Charges from April 1 st 2013 In addition there is a local sub-station tariff which varies from as much as £ per kW at Edinbane on Skye in the SHETL area to as little -£ per kW at Mark Hill in the SPTL area.
Beware!!!! The TRIAD Approaches!!! on 1 st November! What is the TRIAD? A modified measure of peak demand over winter period 45 Demand Connection Charges
46 Demand Connection Charges The Triad occurs in the period 1 st November – 28 th /29 th February It is the mean of the following: 1)The maximum demand in any one half hour in the above time period. 2)The second highest demand in any one half hour provided it is separated from (1) by at least 10 days. 3)The third highest demand in any one half hour period provided that it is separated from (1) and (2) by at least 10 days
47 Demand Zone Name TRIAD Demand (£/kW) Energy Consumed (p/kWh) 1Northern Scotland Southern Scotland Northern North West Yorkshire N Wales & Mersey East Midlands Midlands Eastern South Wales South East London Southern South Western Demand Connection Charges from April 1 st 2013 This table has updated figures for 1 st October 2013
48 Example how TRIAD charges can be mitigated Peak demand occurs at time of TRIAD - form process working Shift process by say 2 hours will reduce the TRIAD charge by over 25% or £ see handout
49 N.K. Tovey ( ) M.A, PhD, CEng, MICE, CEnv Н.К.Тови М.А., д-р технических наук Recipient of James Watt Gold Medal 49 NBS-M Regulated Power Zones and Smart Grids CLIMATE CHANGE GOVERNANCE AND COMPLIANCE
Transmission and Distribution Networks are critical to electricity security. Losses on line: = I 2 R where I is the current and R is resistance the power transmitted P = V * I - V = voltage –Typical UK domestic voltage - 240V –European Voltage - 220V –North American Voltage 110V These are nominal voltages and system must control voltages within a narrow band of this. 50 REGULATED POWER ZONES Voltage%loss relative to 240 V % % % % % Losses are reduced by increasing voltage
The consequence of resistive losses is that the transmission and distribution cables heat up and may typically be running at 50 o C+ As they heat up they expand and the cables will sag more at mid-span with a the possibility of a flashover. This means that there will be less sag when the cable temperature is lower – i.e. in winter and also in times of higher wind speeds when the cooling effect of the wind will be greatest. There is thus a maximum power load that any cable can take and this limits the number of connections that can be made. 51 REGULATED POWER ZONES A further problem with AC transmission is that current flows mostly through the skin with much of the cross section not used effectively. Unlike DC
Traditional way to allocate generation connections: Order of application according to potential maximum connection capacity up to total capacity of transmission/distribution line. A safe approach which ensures that transmission/ distribution lines are not overloaded. BUT May not make optimum use of transmission capacity. Example: Suppose a line has 2000 MW capacity – a typical 400 kV ciruit capcity Order of connection allocations: –Generator 1: 1000 MW – say with 2 x 500 MW sets –Generator 2: 500 MW –Generator 3: 500 MW – with 2 x 250 MW sets. 52 REGULATED POWER ZONES
If all sets are generating – 2000MW i.e. capacity of line and no more sets can connect without the expense of transmission line upgrade. If generating sets are fossil fuel, then they may have a relatively high load factor and traditionally that has not been a problem. BUT if say one of Generator 1s sets is not generating, only 1500 MW of the 2000 MW of the line capacity is used. BUT no new generators can connect as the inactive set may come back on line. Grandfathering Rights 53 REGULATED POWER ZONES Generating SetsTotal installed capacity Generator 12 x 500 MW1000 MW Generator 21 x 500 MW500 MW Generator 32 x 250 MW500 MW
54 REGULATED POWER ZONES Problem is exacerbated with generating plant of low load factor e.g. wind and was first identified in Orkney where significant renewable generation threatened to seriously overload distribution system. Orkney is connected to mainland by 1 x 30 MW and 1 x 20 MW cable. A fossil fired power station on Flotta associated with the oil terminal must run for safety reasons typically around 4.5 MW. Burgar Hill had historic rights of around 7 MW with the European Marine Energy Centre (EMEC) a further 7MW also in this category. Thereafter there were several other wind developments which threatened to exceed total capacity of cables to mainland as it was assumed that one of the two cables might be out of action giving only a maximum potential connection capacity of 20 MW.
55 REGULATED POWER ZONES Total Historic Generating Capacity ~ 18.5 MW Minimum Demand in Orkney ~ 7 MW Capacity of smaller cable to mainland ~ 20 MW Maximum Generation on Orkney which would not overload single mainland cable is 27 MW – i.e 8.5 MW new capacity could be connected. But EMEC capacity is often 0 MW, and rarely is Burgar Hill at its rated output. If dynamic dispatch of generation capacity is used much more generation could be connected.
56 REGULATED POWER ZONES Evaluate total system capability at any one time C = mainland connection capacity (i.e. 20 or 30 or 50 MW) + instantaneous demand on Orkney Subtract from this those generating connection which have grandfathering rights, but only up to the amount of instantaneous generation (NOT maximum connection rights) This gives maximum additional capacity which can be connected at that time. If this also is done on a first application first served basis, it would be possible to connect much more renewable generation than otherwise possible. However, it may mean that wind turbines at the end of the queue may not be able to generate when wind speed is optimum and returns on investment are best
57 REGULATED POWER ZONES Suppose C = 60 MW – i.e. both cables operating and demand is 10 MW If Flotta output is 7 MW and EMEC is 7MW and Burgar Hill say 3.5 MW (i.e less than rated connection of 7MW as wind speed is low – i.e. instantaneous load factor is 50%) Available additional connection is 60 – 17.5 i.e 42.5 MW If this were take by additional Wind at 50% load factor then 85 MW of additional capacity could connect. BUT if wind speed increased to rated speed of wind turbines, Burgar Hill would now be at 7 MW and available capacity would be 39 MW. If all of this were as wind turbines at rated output (i.e. 100% load factor) only 39 MW could actually generate and 46 MW would have to shut down at the time they were most productive.
Consequence of Dynamic Regulation of Power Zone More effective use of transmission/distribution cables is made A greater proportion of renewable energy can be brought on line at an earlier stage BUT Those connecting last may find return on investment poor. Lincolnshire RPZ operates only to transmit power from offshore wind farm Does not primarily address demand, but cooling effect on cables to minimise sag In winter – higher wind speeds – greater output capacity from wind turbines BUT weather is cooler and cooling effect of wind on cables is greater so cables can transmit more 58 REGULATED POWER ZONES
ELECTRIC VEHICLES: Widespread deployment of electric vehicles could adversely affect the generation of electricity – leading to less effective use of generating capacity. 59 SMART GRIDS – DYNAMIC REGULATION of DEMAND Existing peak demand occurs around 17:00 the time when most people return home. Owners would potentially would start charging their vehicles potentially exacerbating the load profile Electric Vehicle demand from Dave Openshaw
Electric Vehicles with Smart Charging 60 SMART GRIDS – DYNAMIC REGULATION of DEMAND Strategy 1: Unrestricted charging as per previous slide Strategy 2: Encourage people not to charge between 17:00 and 21:00 with a reduced tariff. Assume 75% take this up ~ would remove light green area. Strategy 3: Discharge remaining store in car batteries to help existing peak. i.e. move green area to red – at further reduced tariff – example shows 25% of people adopting this.
HEAT Pumps: Widespread deployment of Heat Pumps would exacerbate electricity demand 61 SMART GRIDS – DYNAMIC REGULATION of DEMAND Heat Pump demand from Dave Openshaw
62 SMART GRIDS – DYNAMIC REGULATION of DEMAND There is a less peaky demand from heat pumps than electric vehicles because of thermal store benefits from under floor heating, Use of an additional thermal store could help further to fill mid-day peak and lop peak morning and evening periods for charge overnight.