No time for charging stations? Ok then let's charge on the go
Electric Road Systems
In this article, let's learn why electric road systems are a much better solution.
These allow vehicles to charge as they are driving, giving electric vehicles unlimited range, including heavy trucks. All roads don’t need to be fully electrified since vehicles are still expected to have batteries. There just needs to be charging zones along major highways and busy bottlenecks in cities. This is the only current electrification system suitable for heavy trucks. Although heavy trucks are only a small percentage of the vehicles on the road, they produce about one-third of the emissions because they travel long distances at sustained power outputs. Electric roads also make a lot of sense for private cars because they allow smaller batteries to be used, greatly reducing vehicle cost while also reducing weight and, therefore, performance. The capital cost of road electrification may initially seem quite high but is surprisingly cheap when compared to the alternatives.
Issues with Battery Electric Vehicles
A major issue with battery electric vehicles (BEV) is their limited range.Battery technologies are being developed to increase energy density and reduce critical metal content. However, industry experts do not expect the fundamental limitations to change. There is also likely to be a degree of compromise. To achieve very low levels of critical metal content, energy density will be sacrificed.
Types of Electric Road Systems
Electric road systems (ERS) provide a way of powering and charging a vehicle as it is driving along a road. There are three main types of ERS:
Overhead lines*, also known as a catenary system: These are often used for electric railways and trams. They may also be used along highways to power heavy commercial vehicles.
Conductive track*: These are simply conductive metal tracks installed in or on the surface of a road or sometimes along the side of the road.
Inductive track*: These are buried conductive coils below the surface of the road. An electric current is induced in a coil on the bottom of the car.
This would not require all roads to be electrified. Instead, charging zones would be included on long stretches of highways and in busy areas of urban road systems.
Overhead lines are the cheapest form of ERS to install. They are also the most technically mature due to their similarity to systems used by railways, trams and trolley buses. Two conductive lines are suspended over the road at a height of approximately 5meters. This height means that relatively long stretches of over 1km can be safely electrified. Vehicles require a pantograph that makes the connection while compensating for lateral and vertical movements of the vehicle. This means the system is only suited to large commercial vehicles. These systems have been in trial operation since 2016, with testing on public highways in Sweden and Germany.
Although overhead lines are cheap and mature, they have significant disadvantages. The pylons along the roadside are a danger in road traffic accidents and fallen cables may endanger pedestrians. The public may also object to the visual impact of overhead cables, especially in areas of natural beauty. Perhaps most significantly, this system is not compatible with the majority of vehicles, such as private cars.
Conductive tracks work in essentially the same way as the classic toy Scalextric. A retractable pick-up, mounted underneath the vehicle, establishes an electrical connection by sliding contact. Safety is ensured by dividing the tracks into short segments that are only energized when a vehicle is passing over them. An additional layer of safety may be provided by presenting an earth rail at the road surface with the live rail within a deep and narrow slot. Extensive tests of conductive track systems are being carried out in Sweden. Because conductive tracks can be used by both heavy and light vehicles, they appear to have the lowest overall cost.
Inductive tracks, or road bound inductive systems, use an energized coil buried within the road surface to induce a current in a coil on the underside of a vehicle. Inductive charging of buses has been in operation in Korea since 2010, and the Dongwon online electric vehicle (OLEV) is now a mature technology although it is a low-speed system for city buses. Recent trials carried out on highways in France and Italy found efficiency depends on the accuracy of alignment with the coils and is at best 80 percent. The major advantage of inductive tracks ove r conductive ones is that they should require far less maintenance and cleaning. However, when maintenance is required, it may be more expensive requiring the road surface to be dug up.
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