Welcome Your IET account
Car charging

Plug-in power

Ask yourself: ten years from now, will you be driving an electric vehicle? Many people hope you will – but the electricity networks are not so sure.

The role of Electric Vehicles (EVs) in delivering a sustainable transport system is beset by controversy. To critics, the vehicles represent a poorly conceived plan to reduce emissions, while to supporters they are an essential component of a sustainable transport mix. It comes as no surprise then, that there is such a disparity between predictions of how readily drivers will rush to purchase the new breed of car: forecasts for new-car sales share ten years from now fluctuate wildly between 2 per cent for the most pessimistic and 10 per cent for the most optimistic.

A report from the influential Deloitte Consulting published last spring set the bar at 5 per cent, while global consulting company PRTM are slightly less optimistic at a point lower. Then you have manufacturers such as Nissan predicting in excess of 10 per cent sales.

Critics point to the fact that it has taken hybrids ten years to garner a miserly 3 per cent of new car sales: but even if EVs only captured 3 per cent of the market that would be a significant amount of cars. Sales figures for 2010 are predicted to top 80 million, and despite the global financial crisis this figure is expected to grow by around 4 per cent a year, fuelled primarily by the growing markets in China and India. That would set the sales for 2020 at 118 million, and a 3 per cent slice of that would be 3.45 millions cars, not sales to be sniffed at.

How will we use electric vehicles?

If the more optimistic predictions hold true then 10 per cent of sales would see 12 million new EVs on the road. 'The automotive industry is bedevilled by fundamental questions of how consumers will accept and use electric vehicles,' John Gartner, senior analyst at Pike Research, says. 'There is still uncertainty about the issues of price sensitivity, range anxiety and the importance of charging station networks, the length of time required to charge EVs, and other important matters. These questions can only be answered through real-world experience that is gained from commercial launches. 2011 is the year in which many of these answers will come into greater focus.'

'In the UK the plug-in car grant and company car tax incentives will facilitate a move towards ultra-low carbon transport in many commercial fleets,' Ian McDonald, technical director of future transport systems, member of the IET transport policy group and chair of the IET EV Infrastructure technical group, explains. 'With most of the major automotive manufacturers poised to introduce EVs and E-REVs [Extended Range Electric Vehicles] over the next two years, it is reasonable to expect a second surge in uptake in around three years when previously-used fleet vehicles exit their commercial lease period and are in reach of the private market.'

This will potentially coincide with a self-sustaining market where government incentives are no longer offered (or indeed required) as oil prices reach a tipping point and electric and plug-in vehicles are considered as viable financial alternatives to conventional engine vehicles. 'Market penetration will ultimately be dependent on the availability of a range of vehicle types offering different options to different customers,' McDonald adds.

Grid under pressure

The launch this year of serious models from major manufacturers is likely to see an initial surge of EVs, especially in key urban areas and regions such as California, where legislation is making them an attractive option. According to official state estimates there will be in excess of 5,000 EVs and plug-in hybrids sold in California alone next year. This rapid growth is viewed as both an opportunity and a challenge by many utilities.

Southern California Edison, the power utility, explains that it feels the most popular charging option will be a 240v home charge that will charge the battery in around three hours and will draw around 6.6kW from the grid. Plugging three cars in on a single street is equivalent to adding three new homes to the neighbourhood. Press reports have suggested that turning on more than a handful at once will put great pressure on street level transformers that are traditionally considered to be the weakest link on the grid.

'There will be pressure on the grid, but utilities are more than aware of the need to upgrade their infrastructure, particularly at a local level, and plans are in place to do this at whatever speed is required to match public demand for EVS,' Sunil Chhaya, senior manager of OEM PHEV programmes at Electric Power Research Institute, explains.

So what are the big challenges when it comes to charging electric vehicles? According to McDonald, they are manifold.

Currently the undefined 7kW connector standard tops his list, but he expects a UK position will resolve this soon. He also includes the time it will take to install recharging posts including installation of cables and metering.

'Another thing is traffic regulation orders for road markings, and not forgetting connect times for the unit from the distributed network operator,' he adds. 'Charging times and the need to reduce them, as well as a real need to manage when vehicles charge using smart technologies to avoid peak demand.'

There is agreement that smart technologies are essential to ensure that EVs do not create a peak demand. There is an expectation that users will charge cars overnight, taking advantage of cheap electricity, but recent research has cast doubts on this with many believing that most EV owners will simply plug their vehicles in when they return from work, putting stress on the grid during its busiest early evening period.

'Smart technology can negate some unnecessary energy supply network upgrades and importantly align charging with renewable embedded generation,' McDonald adds. 'Low-carbon transport will also stimulate innovation, new technologies and services that are essential in sustaining a lower-carbon lifestyle. In the last decade we have transitioned to a plug-in society, it therefore comes as no surprise to the new multimedia-enabled generation that transport should be any different.'

Home or away

Another debate raging in EV circles is one about the charging habits of users. There is a great rush, and plenty of government money, being ploughed into providing a charging infrastructure at various key points around major cities and roads. But are they the way forward? With charging times currently measured in hours, rather than minutes, many believe that most charging will be carried out at home, although to extend the limited range of the first wave of cars some fast-charge points will be required.

'Not everyone will be able to charge at home; in fact a study carried out for the [east of England's] EValu8 plugged-in places suggests that a sizeable percentage of early private adopters will live in properties without garages,' McDonald says. 'I do believe however that there is an optimal level of street-side recharging – a level yet to be defined – but it is also worth remembering that a mix of free parking and free charging are part of the current decision matrix for some considering switching to an EV.

'To tether an EV to its own home-charge unit is under-utilising the capacity of the EV to commute and extend its overall range through the use of publicly accessible recharging point at various charge rates.'

One thing is readily apparent: there are still more questions than answers when it comes to EVs. Some, such as common connection standards, may soon be settled, but others will only become clearer once EVs begin to be used in larger numbers allowing stakeholders to make decisions about future investment based on real experience of consumer habits.

Sign up to the E&T News e-mail to get great stories like this delivered to your inbox every day.

Recent articles

Info Message

We use cookies to give you the best online experience. Please let us know if you agree to all of these cookies.

Learn more about IET cookies and how to control them