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Greatly increased electric vehicle use will be an essential tool in meeting difficult future carbon dioxide (CO2) emissions reduction targets, but - if enough of them find their way on to UK roads - they will result in higher electricity demand. Voltimum UK managing editor James Hunt introduces this VoltiTECH about electric vehicles (EV) infrastructures and asks: 'Will supply systems cope?'
An EV uses one or more electric motors for drive, instead of the ubiquitous internal combustion engine. EVs include electric trains, boats, motorcycles and scooters, and even spacecraft. However, what we are concerned with in this VoltiTECH is electric cars, light trucks and neighbourhood EVs, and the electric infrastructures that will be needed to cope with them.
An EV's electric motors are driven using motor controllers with power from large re-chargeable battery packs installed in the vehicle. There are other types of stored energy electric vehicle, but they are very small in number.
Another relatively common type, though, is the hybrid electric vehicle (HEV). This uses electric motors in conjunction with conventional thermal power plant, such as petrol engines, plus a larger generator. Such cars can be driven by the engine, or by electric motors. The engine charges the battery in the normal way, which can then be used to power the electric motors. Braking regeneration also helps keep batteries charged. Toyota's Prius is the most famous example. Hybrids that can also be charged externally are called plug-in hybrid electric vehicles (PHEVs). Toyota has launched trials of such a PHEV that combines Prius and pure EV benefits. EDF Energy has been installing charging points across London for it.
HEVs are more energy efficient than conventional fossil-fuelled vehicles, but EVs are much more so, and CO2 emissions can be greatly reduced. Many EVs will be required to replace conventional vehicles to help meet the UK Government's 2020 CO2 reduction target. Of course, this energy must come from another source - the electricity grid. As EV sales are still small, but are starting to grow, driven by environmental and fossil fuel price concerns, this could become a problem.
Though battery costs are expected to fall sharply, it is predicted they will still represent a cost of around £6000 per vehicle to the consumer. Therefore, electric car prices will be largely reliant on electricity prices and government incentives. So, while EV projections are uncertain, a conservative estimate is around 500,000 UK units by 2020. However, new figures (by WWF-UK today) indicate that at least 1.7 million EVs will be needed by 2020, and 6.4 million by 2030, if the UK is to achieve its climate change targets. Still higher EV numbers would reduce the UK's dependency on oil further.
Charging technologies:
Part-1 of IEC 62196 - This relates to plugs, socket-outlets, connectors, inlets and cable assemblies for EVs. This standard uses the charging modes as defined in IEC61851-1. These are:
IEC 61851-1 - Mode 1 - slow charging from a household-type socket-outlet.
IEC 61851-1 - Mode 2 - slow charging from a household-type socket-outlet with an in-cable protection device.
IEC 61851-1 - Mode 3 - slow or fast charging using a specific EV socket-outlet with control and protection function installed.
IEC 61851-1 - Mode 4 - fast charging using an external charger.
The recommendation is that the normal charging mode for domestic house electrical circuits be Mode 3. Note, though, that too much fast charging can reduce battery life. This is to be avoided, as battery packs can typically cost £6000 to £8000. However, fuel cost savings using EVs can be offset to help pay off new battery pack leases.
The act of recharging an electric or hybrid vehicle is not trivial, given the power of the supply involved, handling supplies that are higher than 2kW, in private dwellings, is highly uncommon. The electrical network is interfaced with the socket and associated recharging system and, for the safety of people and equipment, it is essential to choose them well.Standards are as follows:
- Fixed installations - CEI 60364
- Conductive recharging system - CEI 61851 (TC 69)
- Equipment - EV electrics (if it is not recharging) - ISO TS 22/SC 21
- Battery cell array - CEI SC 21A
- Battery - ISO TC 22/SC 21
- Data transfer - JWG CEI/ISO - V2G
- Connection interfaces - CEI 62196 (SC 23H).
Sockets are Type-1, Type-2 and Type-3, which are single-phase (32A - 250V), single-phase / three-phase (70A single-phase; 63A three-phase 0 - 500V), and single-phase / three-phase (32A - 500V). The Type 3 socket, together with recharging Mode 3 provides optimal safety and performance for users, as the protection level is identical to that of industrial applications.
In most cases, EVs can be charged from a standard electric socket, so businesses or individuals can recharge them at their own premises and homes. However, there is also a growing network of public and private charging points, some of which are currently free - though they will not be free for ever. Some charging networks work on a model where, for a small subscription, users can access a network of charging points, with charging cable, free parking in certain areas and points etc provided - but the electricity used has to be paid for.
Typical public charging points are posts, which are suitable for indoor and outdoor use, are fitted with a plug socket mounted near the top, and a coiled power lead supplies 240V AC at 13A - suitable most EVs. The covered socket is unlocked and opened by a radio-frequency identification (RFID) tag, which is usually held nearby, perhaps by a car park attendant or by shopping centre facilities management. Users can obtain the tags in return for showing some form of ID.
Plans also include a proposal to provide EV users with a generic smartcard, which will allow them to access all charging stations, not just those within their local scheme. POD Points are the latest charging points that are compatible with existing electric car charging tags. Users simply swipe the tag, open the socket, plug in and charge, but they have to supply their own cable for these. Some charging stations provide one or a range of heavy duty or special connectors. Charging is also possible without a physical connection using parking places equipped with inductive charging mats, but more development is needed for these.
Some charging stations can charge several EVs together. Current or connection sensing mechanisms disconnect the power when the EV is not charging. This is to avoid danger in case an EV is carelessly driven away before being unplugged, so tearing away the charging cable insulation and exposing the conductors.
Because of the risk that many EV owners will start charging in the early evening, coinciding with maximum demand and putting grids at risk, EV manufacturers and others are developing sophisticated integrated information and charging systems. For example, charging infrastructures will need to know where suitable charging points are located for individual consumers (drivers), so that they can - if required - book charging points at times and places that suit them. Indeed, scheduling systems are being developed that allow scheduling to (perhaps from PCs and smart phones) and billing from charging points, with supervisory control from elsewhere using intelligent networking systems. Much discussion is ongoing with networks providers into how best to optimise charging regimes.
Charging in application:
EDF Energy has partnered with Peugeot UK and Citroën UK to offer residential and fleet customers EV recharging products and services with the sale of every Peugeot iOn or Citroën C-Zero. This partnership is aimed at supporting the development, future marketing and up-take of fully electric and plug-in hybrid vehicles.
The residential package, which includes a free site survey, makes it even easier and faster to charge these electric cars. Following a free home survey and the installation of a dedicated charging point, drivers can benefit from faster charging times of up to 35%. The package also includes a timer to enable easy off peak recharging, a smart meter and an EV consumption statement that shows owners the cost of charging the car. The first 500 residential customers will also receive 1,000 electricity miles free. This package, with three-year charge point guarantee, costs £799.
One scheme has been EDF Energy's low carbon charge point package that allowed EV households to save money by receiving 20% cheaper electricity during evenings and weekends with the Eco 20:20 tariff. In trials, the company found that 66% of home charging was carried out during the evening and weekends, making Eco 20:20 an ideal tariff for EV owners.
In another initiative, Schneider Electric was believed to be the first company in the world to have an EV charging infrastructure ready for Renault's Z.E EV range, and in a joint venture between Ford, Hillingdon Council, Scottish and Southern Energy (SSE), and the Technology Strategy Board (TSB), Chargemaster (http://chargemasterplc.com) was chosen as the primary provider of electric charging posts to be installed across the London Borough of Hillingdon. Chargemaster claims to be leading the way in creating a network of interoperable charging posts across England.
London Mayor Boris Johnson has switched on the Source London charging network, making it easier for owners to use public charging points. Part of the government's 'Plugged in Places', Source London joins existing charging points under one scheme. Members can use a single electronic RFID card, which unlocks any London charging point. Membership costs £100/year and allows free charging at the point of access. Currently, London has only a few hundred charging points, but Johnson plans to install a further 1,150 public points in residential streets, supermarkets, public car parks, shopping and leisure centres by 2013. At the time of going to press, it is not known how many of these have been implemented.
However, the Green Party has accused Johnson of never explaining how he would fund his original plans for 25,000 charging points that he launched in 2009, nor has he guaranteed that charging points will run on renewable energy - so any environmental gains will be significantly reduced.
The coalition Government's latest plans to develop a publicly-available EV charging infrastructure, outlined in 'Making the Connection: The Plug-In Vehicle Infrastructure Strategy', focuses charging point installation in those areas where consumers are most likely to charge their vehicles, such as supermarkets, retail centres and public car parks. It should also facilitate EV charging at home and at workplaces, and provide 'focused' roadside charging points for EV users without off-road parking. However, original plans for an extensive network of charging points countrywide have been abandoned. The coalition Government believes most EV drivers will charge their vehicles overnight at home - the reason given for the row back, but many believe it is a cost-cutting exercise.
In addition, some workplaces are starting to provide dedicated EV parking bays with chargers provided. Even Google got in on the act, promoting use of electricity for personal transportation. In the USA, Google has added EV charging stations to its mapping service - this is currently only available in the US, although the company hopes to bring the service to other regions soon.
Parkeon (www.parkeon.com/uk), the pay and display terminal, end-to-end solutions for on-street and off-street parking and fare collection for public transport specialist, has been working with Schneider Electric on how to develop suitable charging and billing systems for the future.
Demographics may be important, as EVs will be far more common in cities because of their limited range. Local tax differentials and electricity infrastructure differences may have local impacts that have yet to be fully considered. Co-ordinated planning with local distribution companies, Distribution Network Operators (DNOs) and vehicle manufacturers will be essential. It is likely that the DNO concerned will need to be notified when intending to install a charging point.
Will electricity demand be met?
Plug-in electric vehicles (EVs) use battery packs to power electric motors that are controlled by the driver via electronic drives, and - depending on how often and how far they are used, may need daily recharging.Another type is the hybrid electric (HEV). This uses electric motors in conjunction with conventional engines, plus a generator. Toyota's Prius is the most famous example. Hybrids that can also be charged externally are called plug-in hybrid electric vehicles (PHEVs). Toyota has carried out trials of such a PHEV that combines mild hybrid and pure EV benefits.
HEVs are more energy efficient than conventional vehicles, but EVs and plug-ins are much more so, and CO2 emissions are greatly reduced. Many EVs will be required to replace conventional fossil-fuelled vehicles to help meet the UK Government's CO2 reduction targets. Of course, this energy must come from another source - the electricity grid. As EV sales are starting to grow, driven by environmental and congestion incentives together with increasing fossil fuel prices, there are concerns that this could become a problem.
Can electricity demand be met?
How much electrical power will be needed, and can the existing grid and generating capacities cope?
We need to know how many EVs are likely to be sold to 2020, as well as the likely proportions of BEVs and PHEVs. This is not easy to predict because EVs rely on emerging technologies, because a significant optimised electrical infrastructure will be needed, even though many tens of thousands of EVs can be accomodated within the existing infrastructure. Also, people still need convincing.
It is, in addition, necessary to know likely battery technologies (lead acid, lithium ion, lithium polymer or other), as these affect charging rates and costs. Battery charge/discharge efficiencies have to be considered. Also, some EVs use regenerative braking to extend range. This can affect charging. Charging time is primarily limited by the grid connection to the household (typically 3kW - connections to homes are in the order of 24kW); new 10kW charging points may be necessary in some circumstances depending on use scenarios. Remember, though, that petrol pumps too consume a lot of electricity.
While EV projections are uncertain, back in 2008, a conservative estimate was around 500,000 in the UK by 2020. However, it seems that only 465 electric cars were bought in the first quarter of 2011, 215 in Q2 and a mere 106 in Q3 - through the 'Plugged-in Car Grant scheme. In fact, the number of EVs in the UK was only 1,100 back in October 2011, so we have no real idea of how many EVs will be on our roads by 2020.
Even so, as technological advances are made, as prices come down, performance increases and the charging infrastructure develops, EV take up will almost certainly reach a critical mass - one day there will certainly be many EVs on our roads. Another forecast, by Pike Research in a web-based survey, is that by 2015, over one million plug-in hybrid electric vehicles (PHEVs) and EVs will be sold annually around the world. The same research forecast that by 2015, more than three million EVs sold by then will be plugging in to recharge their batteries.
But sticking to the 500,000 EVs in the UK by 2020 figure, what will be the effect on the UK's electricity grids?
The effect on grids:
What effect might these vehicles have on the current transmission system? Assuming that EVs will charge from 3kW mains sockets most of the time (a big assumption), and that prospective battery sizes will be 16 - 22 kWh, that charging will be overnight, and ignoring losses, a National Grid estimate has been that the near instantaneous power demand would be about 2GW, equivalent to around 4 TWh annually. Another calculation has it that 500,000 EVs at 3kW each from domestic socket is 1.5 GW, assuming all at peak power at the same time (which is very unlikely). This is around 1.7% of UK fleet - possibly demanding only 1-1.5TWh.
To power all 30m UK cars could result in an electrical power output increase to from 60 - 93 TWh, giving a 27% increase in annual system energy demand. This might still be met - but ALL charging would have to be by night.
However, this penetration could well be an unrealistic scenario. Growth in use will be progressive and take many decades. Other fuels will still have a role for a long time.
National Grid's probably more realistic 4TWh is modest compared with the UK's 350 TWh annual energy demand. The organisation puts this in context - 4TWh is similar to that expected from the UK's tumble dryers fleet by 2020. A World Cup sized sporting event would also demand a 2GW power pick-up. This is entirely within current capacity, as long as all power stations and contingencies were available. However, it would very desirable not to charge all EVs simultaneously, and to avoid evening charging.
Smart metering will be crucial:
For this reason, completing the 'smart metering' rollout is essential as a complement to EV rollout. This would help optimise national electrical infrastructure use, and also provide appropriate price incentives for EV owners. Smart metering could even automatically switch charging on at night. Good data handling would be essential, though - this would be part of the 'smart grid' strategy, but both hard-wired and wireless advanced data network control and communication systems will be needed.
EVs are a National Grid strategic research priority, and it has been undertaking work in the UK and the USA for some years to fully understand the technologies and their implications.
The effect on power generation:
We've looked at possible EV effects on grids, but can the power generators also cope? It will be very important to maximise energy and emissions advantages by re-charging EVs using renewable sources, or at least from highly fuel-efficient (to 90%) cogeneration plant. Even so, National Grid believes that the incremental energy demand from EVs up to 2020 will be satisfied by natural gas fired combined cycle gas turbine (CCGT) plant. What is important is the aggregate grid mix power vs total demand, not which contract supplies which user.
Before it sold its electrical power distribution business, E.ON commented: "As a network company and a power producer, E.ON has to look at both aspects. We've estimated that plug-in EVs could potentially represent 5 - 7% of current total UK vehicle miles by 2020. Based on a typical EV output of 30 - 40kW, this will be equivalent to around 7.5TWh electrical energy - or around only 2.2% of current generating capacity. Our networks will cope.
"However, we will still have to plan new power plant very carefully. Nuclear power is base load, and wouldn't be flexible enough for unpredictable EV charging. We have many wind farms, but the wind doesn't always blow at the right time. This leaves thermal plant. One reason for wanting to build the 1600MW Kingsnorth cleaner coal-fired units (now abandoned) and new gas-fired plants is to meet future power requirements flexibly. These could help cater for demand spikes when EV owners plug-in for recharge. We could reduce such 'spikes' by using 'smart metering' and tariff incentives, but first we need to conduct realistic trials to establish what EV consumers want.
"After 2020, the impact will increase as plug-in EV use continues to grow. Grids will respond, but slowly because of their size and complexity," concluded E.ON.
If E.ON's and National Grid's views are typical, and there is other evidence that they are, then up to 2020 anticipated plug in vehicle power demand should be met. Yet most UK nuclear power stations still running have technical issues currently, including that older nuclear and coal-fired power stations are being, or will be, shut soon. Not only that, but also the Government's plan to build new nuclear plants is well behind schedule. All of this is leading to concern that the country may run short of electricity, even without EVs.
Other aspects:
Because of the risk that many EV owners will start charging in the early evening, coinciding with maximum demand potentially putting grids at risk, some EV manufacturers are reported to be developing sophisticated integrated information and charging systems. They will need to discuss with networks providers about how best to optimise charging regimes.
Demographics may be important, as EVs will be more common in cities because of their still limited range. Local tax differentials and electricity infrastructure differences may have local impacts that have yet to be fully considered. Co-ordinated planning with local distribution companies, Distribution Network Operators (DNOs) and vehicle manufacturers will be essential. Note that it is a common misconception that EVs are an inner city issue. Most commuters in the UK travel only around eight miles each way, which is well within the range of plug-in vehicles.
It is unlikely, then, that existing electricity power generation and transmission is a constraint to the EV development in the short to medium term, especially as - with planning and forecasting, and awareness of market development - capacity can be made available to suit demand. However, it will be important to use future close relationships to consider potential local constraints and to provide solutions to them - such as short-term operational solutions or longer-term investments.
EVs for decentralised power:
There is a new and very interesting possibility. Because most vehicles are typically parked 85 - 90% of the time, EV batteries could be used to let electricity flow from the vehicle to the grid, when connected to it (and not charging). This is Vehicle-to-Grid (V2G). In this way, EVs could conceptually be used as desirable distributed energy sources to buffer power.
V2G possibilities include balancing loads by 'peak shaving' (sending power back to the grid when demand is high), or buffering during power outages. EVs could also buffer wind turbines, effectively stabilising wind variability. Therefore, V2G could, in principle, significantly reduce future EV power demand, as well as adding highly desirable flexibility and redundancy. Bearing in mind that Scottish and Southern Energy has recently warned that centralised fossil fuel-fired generation would have to give way to energy efficiency and generation diversity, V2G could, potentially, be part of the latter.
V2G is a very interesting concept, but there are technical practical and economic challenges in terms of connection to the grid, feed-in tariffs, battery capacity and life, and other impacts such as consumer behaviour. Very careful battery management will be required. We will be looking at it.
The only real alternative to EVs is hydrogen-powered vehicles, but this could mean building an enormous and hugely expensive hydrogen infrastructure. However, some studies have indicated that the infrastructure costs are not as great as might be expected. Note that hydrogen fuel cell vehicles are the only EVs having on-board power generation. Using batteries cuts out the inefficient process of turning electricity into hydrogen and back to electricity again.
Opportunities for electrical contractors:
Though it may seem that EVs, while interesting, are of little value to electrical contractors and installers, the extensive charging and other infrastructures that will be needed can definitely provide big business opportunities for them. It is not just the low voltage charging infrastructures that will be needed right across the UK; intelligent industrial Ethernet and industrial wireless data networks will also be essential to tie the whole giant edifice into the coming smart grids, and to allow the full benefits of sustainable, de-centralised power technologies to be realised. This makes the very real opportunities for enterprising electrical contractors and installers even more exciting longer term, though training will be necessary.
To see still more (different) articles on EVs and EV infrastructures, please click on any of the following links.