A couple of weeks ago I wrote about Sweden’s electric roads, highways fitted with overhead power cables. It’s a good idea, but it has competition. Today, I want to look at another way to build an electric highway.
The trouble with the overhead cables is that they’re only useful to larger vehicles such as lorries and buses. It’s important to lower emissions and pollutants from these vehicles, but to really put a dent in our transport emissions, we need a solution that works for cars. One possible approach here is electric vehicle lanes with inductive charging.
If you’ve ever owned an electric toothbrush, you’ll have seen inductive charging at work. You don’t want metal connectors on a gadget that’s going to get wet, so the charger creates an electromagnetic field rather than a direct current. We have Nikola Tesla to thank for this invention, but wireless charging is only really coming into its own now, 120 years after it was discovered. Many phones and tablets have receivers for wireless charging these days, and wireless charging points are popping up in public places the way wi-fi hotspots did ten years ago.
You can already get wireless chargers for electric vehicles, ready to install in the floor of one’s garage, or under a supermarket car park. The main application for these so far has been for buses, with operators fitting them in terminals and other places where buses park up. Milton Keynes has these for one of its bus routes, giving electric buses a ten minute top-up charge at the beginning and end of the route. Or you could put them under all the bus stops along the way, so that the bus can charge whenever they pause to pick up passengers. That’s called ‘opportunity charging‘, and it’s being done in Mannheim in Germany. The holy grail is ‘dynamic power charging’, where the technology is fitted on the open road, so that vehicles can charge without even stopping at all.
That’s all theoretically possible, but until relatively recently induction charging required close proximity. The electric buses in Milton Keynes have to lower a charging plate to within an inch of the ground. Sending a charge over a larger gap has been more difficult and less efficient, but a lot of research has been going into it and the number of technical hurdles is falling. A bus route in South Korea is now equipped with charging stations along the road. They are 85% efficient across a six inch gap.
So the technology is there, and the benefits are obvious: range becomes irrelevant, and so does a charging point at the destination. It would be no problem to take an electric car on a long journey, without having to worry about where you were going to recharge and what to do while you waited. For city cars and buses, batteries can be much smaller, which means the vehicles carry less weight and are much more efficient. Most importantly, it would sweep away many of the most common hesitations over electric vehicles, opening the way for the electrification of road transport that will be so important to reducing our carbon emissions.
There are a lot of challenges to bringing induction charging to roads of course, but Britain’s Highways Agency is committed to trialing it. Their 2015 feasibility study is a useful primer on the whole idea. They recommend building a demonstration project, one on a private road and then one on a motorway. They plan to work with key customers, the haulage industry in particular, building confidence in the system before it is sold on to EV drivers. Car manufacturers need to get their heads together to standardise charging systems and fit new cars with the relevant receivers for dynamic charging. Construction techniques need to be tested to see how durable they are on the road, and we need to experiment with the various ways to install them to minimise disruption.
Plenty of unanswered questions remain. What are the health implications of driving over strong magnetic fields, especially for people with pacemakers? How will EV drivers be charged for the power they draw, and how will the system know who to charge? Will it actually reduce emissions if a lot of power is wasted? Do we have grid power in the right places?
It’s pretty complicated, but it looks like promising nonetheless. Several governments are investigating dynamic charging as well as Britain. A range of companies are developing the technology, both for roads and for parking places. Car companies are supportive, and there are major business opportunities here. It won’t be this year, but I don’t think it will too much longer before we start seeing the first electric charging lanes.