Inductive lanes: an expensive future

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When someone becomes aware of the problem of the significantly lower energy density of rechargeable batteries compared to tanks, a character-dependent desired solution often crystallizes. For many people who are spoiled by tanks, this is hydrogen: Hydrogen. For me, it was: inductive power supply in lanes. What both ideas have in common is that they never really took off, and both have the same reason, which I'll reveal right at the beginning to avoid all the Internet article wannabes: both solutions are too expensive with too few advantages over the cheaper alternatives. But more on this towards the end of the text.

Start at full throttle

Around 15 years ago, several projects began to seriously develop new technology for inductive lanes. There were a few hurdles to overcome. With inductive energy transmission, the narrowness of the air gap contributes significantly to the transmission efficiency that can be achieved. However, you cannot drive on the highway with the ground clearance of an F1 car under downforce. The efficiency of the systems therefore had to be sufficiently high even with air gaps of 10 cm and more, together with the performance. To achieve this, the project teams had to develop control systems that control the magnetic field so that it is always below the moving vehicle. To do this, the corresponding coils have to be switched in sequence and the object detection, which is also necessary for stationary inductive systems, has to pass over segments occupied by metal parts. None of these were technically impossible hurdles, as the developments at the time prove. Fraunhofer, for example, demonstrated a power supply up to 200 km/h, suitable for the German open highway. The British wanted to become the "world leader" in inductive lanes within ten years; the Highways England agency began testing corresponding systems.

These projects fell asleep again, or rather: They failed to take the next steps from proof-of-concept to the real world. Instead of Fraunhofer's inductive 200-machine lanes, Siemens was awarded the contract for the "e-highways", in which trucks were fitted with pantographs like those on railcars or electric trolley buses. The results were mixed, the whole project more an artifact of the funding landscape than a real alternative to stationary charging with plugs. The biggest problem with e-highways remains that the electricity is only available for trucks. Inductive lanes, on the other hand, could also supply vans and cars. However, such a project on the highway has not yet found its way into the funding paradise, even if approaches could succeed. In 2017, the British also quietly marked their project pages with the words "withdrawn" and "This article is no longer current". Instead, Highways England is now building fast-charging parks with plugs.

Urban restart attempts

In 2020, inductive lane projects were back in the news. One prominent manufacturer had prevailed in the majority of them: the Israeli manufacturer Electreon. Its range includes stationary charging while parked and dynamic charging while driving and, on request, also includes a complete package of an inductive system, for which only monthly fees are paid. The company takes care of everything from construction to billing (Charging as a Service). Electreon's technology consists of ready-made modules that can be produced in series to reduce costs. The coils are laid under the asphalt, with only distribution boxes for the power supply being installed at regular intervals along the roadside. Electreon has designed the technology so that it can be rolled out as easily as possible. The coil modules, for example, are firmly encapsulated and lie next to each other. During installation, the power supply cable can be unrolled in parallel from the same truck.

At Electreon, one receiver module draws 35 kW. That's enough for a car on the highway, even if most of the power is used to maintain speed against wind resistance at 130 km/h. For larger vehicles such as trucks or buses, several receiver coils are used, usually three with a gross output of 105 kW. The Baden-Württemberg energy supplier EnBW initially tested the system in 2020 with its own bus, which runs from the factory premises to local public transport routes. From 2023, public transport lines were added in Balingen, first the bus shuttle to the garden show, and at the end of 2023, regular services began in the town. What all these cases have in common is that, for cost reasons, the induction track will only be built for as long as is necessary to operate the regular service. The three inductive tracks in Balingen are between 100 and 500 m long, plus a charging facility at the Stadthalle stop. The town of Balingen hopes that the project will create a "more innovative image", "enhance the inner-city open spaces" and contribute to the specified decarbonization measures.

The infinite car is not coming

As is so often the case, technology is not the problem. It would be possible to supply vehicles on the highway with inductive power so that an electric car could drive as far as it wanted on such routes. The breaks would then be more human-induced, as with a large diesel tank. However, as always, what counts is not what is technically possible, but what we pay and what we get for these costs. The additional convenience of energy supply during the journey should be clear to everyone. However, the costs are comparatively high. There is an example project in Detroit where Electreon coils were installed. The public sector contributed 1.9  million US dollars to the project. The route was one mile long, i.e. around 1.6 km. That makes around 1.2 million dollars or 1.1 million euros per kilometer. Then there is the non-communicated private investment part. Then there are the receiver units in cars, which account for 750 to 1000 euros extra cost per unit installed.

The route in Detroit is in the urban area, where there are already many power lines. On the highway, there are additional line costs that exceed those of charging parks. Charging parks are being built in places where there are high electrical connection capacities or where they can be installed cheaply. The well-known "Seed and Greet" charging park in Hilden, for example, benefited from data centers and other large consumers in the industrial park, where several megawatts of power were still available. If a longer route is electrified instead of one location, the costs increase. In rail transport, it is estimated that 1.0 to 1.5  million euros are required per kilometer of overhead line. For inductive road traffic, even new construction tends to be more expensive, and retrofitting anyway. The chicken-and-egg problem, together with a whole series of other aspects that have not been considered, are not included: That's a lot of money for the rather small advantage that I can stop at any service station instead of the one where my car reports a free CCS plug with a fat charging capacity. Another comparison with the railroads: there are now railcars with a battery that is sufficient to cover the sections without overhead lines. This is cheaper than extending the overhead line. A comprehensive expansion of inductive lanes on highways is therefore unlikely.

Fraunhofer carried out a study on the subject back in 2009, and its forecast turned out to be correct:

From an economic point of view, inductive technology cannot be expected to be widely used for charging electric vehicles for the moment due to the significant additional costs compared to conductive charging. In principle, however, a regional niche application may arise under certain conditions.

This can be left for another 15 years.

(cgl)