Article Series Dynamic inductive charging in traffic: What are the framework conditions for the technology?

In recent years, several research projects have been conducted to explore the practical implementation of dynamic inductive charging in the field of electric vehicle charging. This innovative technology enables wireless energy transfer, allowing electric vehicles to be charged while in motion. But how exactly does this technology work, and where do we already encounter induction and inductive charging in our daily lives? What potential does dynamic inductive charging hold for public transportation, and what are its implications for the environment, humans, and energy system? This article series addresses these and other questions and looks at dynamic inductive charging from various perspectives.

While the first article focused on the functionality and application areas of dynamic inductive charging, the second article analyzes the framework conditions of dynamic inductive charging technology, including aspects of economics, regulation, and acceptance.

The technological environment of DWPT (Dynamic Wireless Power Transfer) technology for electric vehicles is extremely diverse and encompasses various aspects. To develop a comprehensive understanding of the technology, it is important to consider the economic and technological challenges, as well as the regulatory, ecological, and social aspects. This article highlights these aspects and their significance for the successful implementation of DWPT technology in transportation.

This article presents selected aspects of the technological environment, such as cost-effectiveness, relevant regulations, the CO2 footprint, and technology acceptance. In the ELINA project, the FfE particularly focuses on the last two aspects, technology acceptance and its environmental impact.

Economic and Ecological Sustainability

Below, scientific findings regarding the economic viability and ecological sustainability of DWPT in transportation, particularly concerning CO2 emissions, are analyzed on a qualitative level. Generally, in scientific analyses, DWPT should not be considered in isolation but rather in comparison to a reference technology. Depending on the specific use case, conductive charging technologies, inductively static charging, or overhead line systems can be considered.

Construction measures related to the installation of infrastructure and components play a crucial role in terms of overall costs, especially when carried out specifically for the expansion of DWPT. Investment costs comprise various components such as coils, energy management systems, and sensors. Additionally, road equipment includes the underground installation of cables and coils, as well as the gluing and sealing of the coils [1]. This significant effort and material input result in higher costs on one hand and are also reflected in the CO2 footprint on the other hand. In contrast, the argument is that DWPT infrastructure is less exposed to weather conditions and vandalism [1]. This potential extension of the lifespan and potentially lower maintenance requirements could lead to economic and ecological benefits. However, practical findings are currently lacking to enable a comparison to alternative charging technologies.

In addition to structural measures, the vehicle-side equipment plays a crucial role in the economic and ecological assessment. Besides the installation of a receiver coil, the battery is of great importance [1,2]. Battery manufacturing generally constitutes a significant portion of the CO2 footprint of electric vehicles [1,2,3]. When assessing the ecological impact of DWPT, differences compared to conductive charging may arise concerning battery size and lifespan. DWPT may lead to a smaller battery design, as the range is increased through charging while driving. This results in a lighter vehicle and a reduced CO2 footprint in battery production [1]. Additionally, the continuous charging tends to result in less frequent deep discharge of the battery, which can extend its lifespan and thus reduce the need for new batteries. This has implications not only for the reduction of greenhouse gas emissions but also for the use of raw materials in battery production and the associated environmental impacts [1].

In operation, compared to wired charging, DWPT allows for greater range with less time spent, as charging breaks are eliminated [1]. This time saving can lead to economic advantages through improved utilization, particularly in public and freight transport. In comparison to charging buses or trucks via overhead lines, DWPT technology has the advantage that even lower vehicle types can utilize the same charging infrastructure while in motion.

From an energy perspective, two additional aspects need to be considered. Charging while driving enables the use of renewable energy sources such as solar power even during the day, whereas conductive charging often takes place in the evening. A higher proportion of renewable energy sources during charging contributes to a lower CO2 footprint. However, to fully harness the environmental potential of electric vehicles, the overall system’s power mix must further decarbonize [3]. Additionally, electromobility requires an expansion of the power grid. How DWPT compares in economic and environmental terms to other charging technologies in this area remains an open question.

A comprehensive comparison between different charging infrastructure technologies requires further research on economic and ecological aspects. The ecological assessment will be conducted in the later stages of the ELINA research project. In addition to economic and ecological considerations, the regulatory framework and acceptance of this technology also play a central role, as outlined in the following.

Standards and Regulatory Framework

Standards and regulations play a significant role in establishing the framework for any technology. Although DWPT is not yet widely deployed in transportation, there are already numerous standards and regulations that impact the adoption of this technology. This ensures that safety and quality standards re adhered to, enabling a smooth integration of the technology.

Figure 2 illustrates various standards for DWPT in an electric bus. These standards generally apply to other vehicles as well. City buses are considered heavy electric commercial vehicles, for which specific adaptations have been made in current DC charging standards to accommodate higher voltage and current values [4].

Of particular relevance to wireless charging are two series of standards that establish uniform and efficient power transfer under compensation and resonance conditions for both the vehicle and the infrastructure. DIN EN IEC 61980 outlines the requirements for inductive charging facilities, while ISO 19363 defines specific requirements on the vehicle side [4]. To ensure robustness and functionality in publicly accessible areas under various weather and usage conditions, corresponding test procedures are applied in accordance with IEC 61980-1,-2,-3 [1]. The standard IEC 61980-1 is now also available as a valid national standard VDE 0122-10-1:2021-09.

New standards are also being developed to define requirements for electrified heavy commercial vehicles. However, there is still no uniform European solution for this area. A standard for anchoring system requirements (based on IEC 61851-23) is currently in the application phase [4].

To minimize potential health effects, exposure limits are established. International commissions evaluate scientific studies on the effects of electromagnetic fields, serving as the basis for national legislation. The ICNIRP (International Commission on Non-Ionizing Radiation Protection) is the most prominent of these commissions and is referenced by the WHO, the European Commission, and the German Radiation Protection Commission [5]. The Regulation on Electromagnetic Fields (26th BImSchV) sets limits for static fields as well as for low-frequency and high-frequency fields for stationary installations, but household appliances, for example, are not covered. In this case, harmonized European regulations for equipment and product safety (such as DIN standards) come into play, which in turn refer to the ICNIRP [6].

The ICNIRP establishes reference values for electromagnetic field strengths based on defined threshold levels where health effects have been demonstrated. These reference values are calculated with safety factors and set to ensure they are not exceeded even under the most unfavorable exposure conditions. This ensures that exposure to electromagnetic fields remains safe and without health risks. Different safety factors and limits apply for occupational exposure [6].

The recommendation of the European Council from 1999 for national regulations referred to the reference values published by ICNIRP at the time. The value for the frequency range applicable to DWPT (3-150 kHz) was 6.25 μT at that time [8]. However, the 26th BImSchV now sets a reference value of 27 μT, corresponding to the newer ICNIRP value from 2010 [9,10]. Furthermore, in addition to other aspects of technology acceptance, health effects from electromagnetic fields are discussed. The use of DWPT is contextualized within the explained legal reference values, and a comparison to the everyday object of an induction stove is drawn.

Technology Acceptance – Health Impacts

Societal acceptance can significantly influence the uptake of a technology. DWPT has the potential to alleviate general concerns regarding limited range and charging times by enabling wireless charging of electric vehicles while in motion [1]. Furthermore, DWPT offers increased user-friendliness as it eliminates the handling of charging cables in comparison to conductive charging [1]. On the other hand, challenges such as precise positioning over the coils during driving must be taken into account.

Health aspects stemming from the use of DWPT can also play a crucial role in technology acceptance. On one hand, DWPT technology provides the advantage that no human interaction with charging devices like plugs is required, reducing the risk of accidents. On the other hand, induced electromagnetic fields can potentially have biological effects under certain conditions.

A biological effect of an electromagnetic field occurs when a measurable response follows exposure. However, this is not automatically equated with a harmful effect characterized by an identifiable impairment of health. The biological effect of electromagnetic fields on the human body has been demonstrated and is determined by various factors such as field strength, duration of exposure, and power density [11]. Additionally, the effect depends on the frequency range. High frequencies (100 kHz to 300 GHz) can lead to thermal effects, i.e., heat generation, while low frequencies (0.0175 Hz to 10 MHz) can have irritant effects, manifesting in the stimulation of nerve and muscle cells [10,12,13]. In the overlapping intermediate frequency range (300 Hz to 10 MHz) where DWPT technology operates, both irritant and thermal effects can occur. The duration of exposure also plays a role in the extent of health impacts [1,12].

In general, many everyday objects generate electromagnetic fields, such as hair dryers or screens. The intermediate frequency range in which DWPT operates is increasingly found in household applications, such as induction stoves [12]. Figure 3 compares measurements of DWPT in transportation with induction cooktops. As described earlier, various factors influence the strength of the electromagnetic field. A key correlation is that the intensity of electromagnetic field strength decreases with distance from the source. The farther one is from the source, the lower the exposure. For induction stoves, a wide range of values has been measured. This is due to variations in distance, different operating frequencies, the position of the cooking pot, and the configuration of the coils [12]. The provided measurements (maximum values) for DWPT come from an E-Truck of the ELINA project partner Electreon and were taken both inside and outside the vehicle.

Conclusion

The analysis of the technological environment of DWPT in transportation highlights the diversity of challenges and opportunities. Further research and development are needed to continue examining and evaluating the technology. A gradual implementation on selected routes and continuous advancement can contribute to expanding current knowledge. In addition to the aspects discussed here, there is also potential for further advancement of the technology itself. Currently, challenges remain in developing a billing system, which will be particularly relevant for other use cases such as highways.

To achieve a more sustainable and environmentally-friendly transportation sector, suitable charging infrastructure technologies must be identified based on the specific applications in electromobility. A holistic consideration of all relevant factors is essential to realize a future-ready mobility that meets ecological, economic, and social requirements alike.

Within the framework of the ELINA project, DWPT technology for electric vehicles is being tested in public spaces for the first time in Germany. The FfE is examining the potentials, acceptance, and emissions of DWPT technology in public transportation. The results will be presented in the following contributions of this series.

The EMADI project also focuses on DWPT, but its primary focus lies in developing a billing system for the use case on highways. Here, the FfE is expanding the existing ecological assessment to include the consideration of the entire lifecycle and gaining additional insights into battery aging.

More Information

• ELINA – Deployment of Dynamic Inductive Charging Infrastructure in Public Transport
• Standardization Landscape for Electromobility

Literature

[1] Burkert, A.; Fechtner, H.; Schmuelling, B. (2021). Interdisciplinary Analysis of Social Acceptance Regarding Electric Vehicles with a Focus on Charging Infrastructure and Driving Range in Germany. World Electr. Veh. J., 12, 25. https://doi.org/10.3390/wevj12010025

[2] Bi, Z., Song, L., Kleine, R., De, C., C., & Keoleian, G. A. (2015). Plug-in vs. wireless charging : Life cycle energy and greenhouse gas emissions for an electric bus system. Appl. Energy, 146, 11–19. https://doi.org/10.1016/j.apenergy.2015.02.031

[3] Agora Verkehrswende (2019). Klimabilanz von Elektroautos. Einflussfaktoren und Verbesserungspotenzial., https://www.agora-verkehrswende.de/veroeffentlichungen/klimabilanz-von-elektroautos/

[4] DKE – Deutsche Kommission Elektrotechnik Elektronik Informationstechnik in DIN und VDE Stresemannallee 15, 60596 Frankfurt am Main; www.dke.de (2021): Technischer Leitfaden Ladeinfrastruktur Elektromobilität – Version 4; https://www.vde.com/resource/blob/988408/750e290498bf9f75f50bb86d520caba7/leitfaden-elektromobilitaet-2016–data.pdf

[5] RWTH Aachen (2023): Festlegung der Grenzwerte, EMF-Portal;  https://www.emf-portal.org/de/cms/page/home/more/limits/limit-values

[6] RWTH Aachen (2023): Grenzwerte in Deutschland (Allgemeinbevölkerung), EMF-Portal; https://www.emf-portal.org/de/cms/page/home/more/limits/limit-values-in-germany-general-public

[7] FEA (2017): FEA Merkblatt zum Kochen mit Induktion; https://fea.ch/de/downloads/merkblaetter-zu-energieverbrauch-und-messnormen/induktion/fea-merkblatt-zum-kochen-mit-induktion.pdf

[8] ICNIRP (1998): ICNIRP Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 GHz); https://www.icnirp.org/cms/upload/publications/ICNIRPemfgdl.pdf

[9] ICNIRP (2010): ICNIRP Guidelines for limiting exposure to time-varying electric and magnetic fields (1 Hz – 100 kHz); https://www.icnirp.org/cms/upload/publications/ICNIRPLFgdl.pdf

[10] Bundesamt für Justiz (2013): Sechsundzwanzigste Verordnung zur Durchführung des Bundes-Immissionsschutzgesetzes (Verordnung über elektromagnetische Felder – 26. BImSchV) Anhang 1 (zu §§ 2, 3, 3a, 10) (BGB. I 2013, 3270); https://www.gesetze-im-internet.de/bimschv_26/anhang_1.html

[11] WHO (2016): Was sind elektromagnetische Felder? Gesundheitliche Wirkungen im Überblick; https://www.who.int/news-room/questions-and-answers/item/radiation-electromagnetic-fields

[12] Fachverband für Strahlenschutz e.V. (2019): Leitfaden „Elektromagnetische Felder“; https://www.fs-ev.org/fileadmin/user_upload/04_Arbeitsgruppen/08_Nichtionisierende_Strahlung/02_Dokumente/Leitfaeden/Leitfaden_Elektromagnetische_Felder-FS-2019-180-AKNIR_20191017_a.pdf

[13] Bundesamt für Justiz (2016): Verordnung zum Schutz der Beschäftigten vor Gefährdungen durch elektromagnetische Felder (Arbeitsschutzverordnung zu elektromagnetischen Feldern – EMFV), (BGB. I 2016, S.2531); https://www.gesetze-im-internet.de/emfv/BJNR253110016.html

[14] FEA (2017): FEA Merkblatt zum Kochen mit Induktion; https://fea.ch/de/downloads/merkblaetter-zu-energieverbrauch-und-messnormen/induktion/fea-merkblatt-zum-kochen-mit-induktion.pdf