Electric Road Systems (ERS) is a technology area with immense potential to reduce fossil fuel dependency, reduce greenhouse gas emissions, reduce air pollution as well as reduce noise in urban environments, while increasing energy efficiency in the transport sector.
ERS is defined as a system enabling power transfer from the road to the vehicle while the vehicle is in motion and could be achieved through different power transfer technologies such as rail, overhead line, and wireless solutions.
The implementation of ERS at national and international levels is likely to work together with the application of other solutions for cleaner transportation. There are several ongoing studies and demonstration projects on Electric Road Systems (ERS) around the world which have the aim to explore different techniques for energy transfer and different use cases. The various ERS technologies have different maturity, and each ERS solution has its own advantages and disadvantages.
The electrification of long-haul freight transportation has been the driving force ERS and continues to be the focus for several activities. Road electrification can however be utilized for various kinds of vehicles, e.g. trucks, buses and cars, even though not all types of ERS technologies are suitable for all kinds of vehicles.
An overview of ERS is given below, for more information see the report Overview of ERS concepts and complementary technologies from the CollERS project, as well as the architecture model developed in the project Research & Innovation Platform for Electric Roads.
Currently, there are three main power transfer concepts for road electrification: overhead conductive lines, conductive rails in a road surface, or wireless solutions. All these concepts have their advantages and disadvantages and are being developed and marketed by different actors.
An overhead line solution uses conductive wire lines (also known as catenaries) above the vehicle to provide the energy. The energy is transferred to the vehicle by means of a power receiver device (sometimes called a pantograph) installed on top of the vehicle, and which follows and detaches automatically from the overhead lines.
A rail solution for conductive energy transfer from roadway to electric vehicles uses conductive rails installed in the road to provide the needed energy. The energy is transferred to the vehicle via a power receiver pick-up arm installed beneath the vehicle, and which follows and detaches automatically from the rail.
A wireless solution uses a magnetic field to provide the energy. Electric current in primary coils installed in the roadway create magnetic fields which induces current in a secondary coil installed beneath the vehicle.
An Electric Road System (ERS) consist of five different subsystems:
The electricity supply consists of transmission, distribution and management components. Transmission includes how the electric power flows from the generation sources over long distances. Distribution is how the power flows through a grid to the power transfer subsystem. The management component controls the operation and balance the energy.
The road subsystem consists of pavement, barriers and auxiliary components. The pavement includes the actual structural body and road markings. Barriers includes both safety and noise protection components. Auxiliary components are road signs and other necessary roadside components.
The power transfer subsystem is divided into three components: road power transfer, vehicle power transfer and control. The road power transfer component consists of in-road and/or roadside equipment that handles detection of the vehicle and transferring of power from the road. Vehicle power transfer controls safe activation and operation of a power receiver, and measures transferred energy after successful acknowledgment. The control component monitors the energy handover and system operation.
The electric road operation subsystem controls the energy management of the overall system, provides user information and handles payment and billing. This subsystem also handles access and lane control of the road based on vehicle identification.
The vehicle subsystem includes the necessary component that converts the power from the power transfer subsystem into either propulsion of the vehicle or to energy storage. A control component provides user information, fleet management and vehicle positioning.
References to the information below are given in the report Overview of ERS concepts and complementary technologies.
Siemens has worked with overhead catenary lines, and its technology named eHighway has been tested on a 2 km closed test track east of Berlin, Germany. Full vehicle integration has been made with heavy trucks from both Scania and Volvo Group. The Siemens solution has been demonstrated since 2016 together with Scania trucks by Region Gävleborg along 2 km of the E16 highway outside Sandviken, Sweden. The eHighway solution has also been demonstrated during 2017 by South Coast Air Quality Management District together with three different trucks along one mile of an urban road in the City of Carson in Los Angeles County, California, USA.
Alstom has a service-proven power system for tramways called APS which supplies electricity through a third rail at ground level and eliminates the need for overhead lines (in order to meet new requirements for tramways in urban areas). The APS product is used in many cities for energy transfer during movement and has been used as a foundation when Alstom has developed its ERS system that involves two rails in the road surface level. AB Volvo has developed power receiver pick-up arms for heavy transport vehicles and tests have been made at a Volvo test site in Sweden. The vehicle integration was performed as part of the Slide-in research project.
Elonroad is a solution with a rail that consists of short segments in sequence. The rail is intended to be installed on the road surface and rises about 5 cm and has slantwise sides. The power receiver device has at least three contacts. Demonstration along a test track is ongoing in southern Sweden.
The rail solution from the company Elways involves one rail with two trenches where the conductive parts are placed down in the trenches. The rail and a customized power receiver pick-up arm integrated into a medium sized truck have, since 2018, been used for demonstration of electrified shuttle transports along a public road in the vicinity of Arlanda Airport, outside Stockholm, Sweden. The Elways solution has had many years of development and tests in various environmental conditions.
The commercial company OLEV, a spin-off of the university KAIST in South Korea, has developed technology for wireless power transfer to buses. Its solution has been tested on a public road inside KAIST’s Daejeon campus since 2012. Since 2013, a bus route of 24 km traversed by a few buses has been in operation in Gumi with a total of 144 m of installed coils.
Bombardier has been conducting research on dynamic wireless power transfer as an evolution of its Primove commercial static solution. The system has been integrated into a Scania truck and tested in 2013 on an 80 m closed test track in Mannheim, Germany, as part of the Slide-in project.
The large EU project FABRIC has built two facilities for demonstrations of dynamic wireless power transfer: a test track outside Torino, Italy, using a Fiat van and power transfer technology developed by SAET group and the university Politecnico di Torino, and the Vedecom test track in Satory, France, using a Renault van and power transfer technology based on a commercially available static wireless solution from Qualcomm. The FABRIC project concluded its demonstration activities at the end of June 2018.
A test track for dynamic wireless power transfer has been completed at Utah State University using technology developed by WAVE. A system in the range from 25 kW to 40 kW can be tested using a 20-seat passenger bus.
In recent years the Israeli company Electreon (previously Electroad) has been known for its ambition to enable large scale adoption of pure electric buses by developing a dynamic wireless electrification system for urban transportation.
The technologies described above are the most well-known. But there are more developments and technologies going on around the world and we foresee that more developers and manufacturers will be active in the coming years. For example, Honda R&D in Japan has worked with an ERS lane on the side of the road and performed tests of high power charging at high speeds. In addition, high ambitions from China have been expressed in news media.
Demonstration projects currently under way will test ERS on public roads and in real-life environments, addressing various legal, political, economic, and efficiency aspects of ERS. Public road tests would provide decision makers and investors with a foundation for further investments that would bring ERS to commercial operation. At the time of writing, there are two ongoing demonstrations on public roads in Sweden, one demonstration on a public road in the USA has been finalized, and the German federal government funds the construction of three future demonstrations on public roads, which will be successively put into operation from 2019 onwards. In addition, the Swedish Transport Administration has issued a pre-commercial procurement in order to gain knowledge from additional demonstrations on public roads.
The following table gives a summary of ongoing and planned activities on public roads:
|Name||Location||Solution||Start of vehicle operation||End|
|OLEV||KAIST Daejon campus, South Korea||Wireless||2012|
|E16 Electric Road||E16 in Region Gävleborg, Sweden||Overhead lines||2016||2020|
|SCAQMD||Los Angeles County, USA||Rail||2017||2017|
|eRoadArlanda||Arlanda Airport, Sweden||Rail||2018||2019|
|ELISA||A 5, Germany||Overhead lines||2019||2022|
|FESH||A 1, Germany||Overhead lines||2019||2022|
|eWayBW||B 462, Germany||Overhead lines||2020||2023 |
|Smartroad Gotland||Visby, Sweden||Wireless||2019 ||2022 |
|Elväg Syd||Lund, Sweden||Rail||2019 ||2022 |
 Planned end year for eWayBW, not approved at the moment.