Electric cars, buses and trucks have an advantage of virtually zero pollution within densely populated urban areas. It does not mean that using them excludes air pollution completely, the pollution is just relocated from urban areas to less populated areas where electric power plants are built. But still it is an advantage.
However, they have disadvantages too. Energy capacity of electric batteries is much lower than energy capacity of gasoline fuel tanks per unit of volume and mass. If a typical gasoline-powered vehicle can run 400 to 600 km (or more) after its tank is filled, an electric car can run only 100 to 150 km on a fully charged battery, even though the battery is much bigger and heavier than the full fuel tank.
Besides, it takes several minutes to refuel a tank, while recharging a battery takes several hours (though, there are experimental batteries that can be recharged much faster, in 15 minutes).
South Korean Scientists and engineers see a solution in recharging the batteries of electric vehicles while they move. Of course, a special design of the road and the vehicles is needed for this. They suggested installing special electromagnetic inductors under the surface of the roads and similar inductors under the floors of the vehicles. When the inductor of a vehicle is above one of the inductors of the road, electric energy can be transmitted from the road to the vehicle via electromagnetic field, similar to how it is done in electric transformers.
Also the road needs to be equipped with sensors, which can detect vehicles and determine which of them have inductors, and a control circuit, which will activate only those inductors in the road, over which there are electric vehicles with receiving coils.
An experimental road of this kind was built in South Korea in 2013. It is only 12 km long and initially only two public busses powered by rechargeable batteries and equipped with charging inductors were running on it. By 2016 ten more buses were added.
This system is much more costly and less energy efficient than systems with overhead energy supplying wires, like in case of trolleybuses and trams. However, their advantage is that when such roads are built all across the city, you do not have to tie the route of the vehicles to the wires. Skeptics argue that so far the cost of building such roads all across a big city is prohibitively high.
This text is based on the information presented in the BBC science radio programmes.
