Railway electrification and wireless power: Technology advances
Charging coils, motorway trials, battery swaps and long-range lasers
What this tab covers The newest technologies in service or close to adoption, what each improves, and how the main options compare.Rail electrification is mature and the advances are in reusing braking energy and cutting build costs. Wireless charging has reached high power in the laboratory but in-road schemes have mostly stalled at demonstration, battery swapping is commercial in China, and power beaming remains experimental.
Latest advances
Polyphase wireless charging coil demonstration · 2024ORNL's compact multi-phase coil transferred 100 kW into a passenger car.5
Improves: 96% efficiency and 8 to 10 times the power density of conventional coils; battery charge rose by 50% in under 20 minutes.
In-road inductive charging (Detroit) demonstration · 2023Electreon coils under a quarter mile of public street in Detroit, with a full mile planned.6
Improves: Charges fitted vans and buses while they drive, so they can carry smaller batteries.
Motorway inductive trials (France, Italy) demonstration · 2025Vinci Autoroutes and Electreon fitted coils along 1.5 km of the A10 near Paris between January and April 2025; first results in October 2025 reported average power above 200 kW and peaks above 300 kW to a lorry, van, car and bus. Italy's Arena del Futuro track on the A35 Brebemi has tested a car and an electric bus.141524
Improves: Tests charging of heavy vehicles at motorway speeds.
Battery swapping networks in service · 2023-2026China had 3,567 swap stations at the end of 2023, 2,333 of them run by NIO; NIO passed 4,000 stations in August 2026 and CATL's Choco-swap network passed 2,000 in July 2026.92021
Improves: A full 'refill' in about five minutes.
Long-range laser power beaming research · 2025DARPA's POWER programme with a receiver by Teravec Technologies delivered over 800 W at 8.6 km; Phase 2 will test relays and vertical beaming.8
Improves: Could power drones or remote sites without cables or fuel convoys.
Energy-optimised metro operation demonstration · 2017Coordinated timetables and driver advice systems.4
Improves: Raised braking energy reuse from 80.6% to 95.5% in a modelled case study and cut traction energy by 16% in a Beijing field test.
Comparing the options
| Option | Efficiency | Cost | Capacity or distance | Maturity |
|---|---|---|---|---|
| Overhead catenary, 25 kV AC23 | High; low current keeps line losses small | About £750,000 to £1 million per single-track km in well-run UK projects (2019) | Heavy freight and high-speed trains over any distance | mature |
| Third rail, 600 to 750 V DC22 | Lower than 25 kV because of higher currents; a UK seminar estimated AC uses about 15% less energy for similar duty | Not quantified here | Metros and commuter systems | mature |
| Static and in-road wireless charging5614 | Up to 96% in laboratory vehicle tests | Detroit development contract US$1.9 million (2022) | 100 kW to a car demonstrated; road sections about 0.4 to 1.5 km | demonstration |
| Battery swapping9 | As for plug-in charging | At least 1.5 million yuan per station; 80 to 100 yuan per swap | Station network serving cars and fleets | early commercial |
| Laser beaming8 | Over 20% at short range | Not published | Hundreds of watts over about 9 km | research |
For trains, wires remain the clear choice wherever traffic is heavy: they are efficient and proven, and the debate is about construction cost. For road vehicles, plug-in charging and swapping compete with in-road charging; in-road schemes promise smaller batteries but need many kilometres of road works before they are useful, which is why Sweden and Germany stopped their electric road projects. Beaming trades very low efficiency for reach where nothing else can deliver power.
Sources
- TSI Energy: technical specification for interoperability of the energy subsystem, Regulation (EU) No 1301/2014 (presentation) European Union Agency for Railways (ERA), 2020
- Electrification Cost Challenge Railway Industry Association (RIA), 2019
- System energy optimisation strategies for DC railway traction power networks (PhD thesis) University of Birmingham, 2017
- Novel technology reaches 100-kW wireless power transfer for passenger vehicle Oak Ridge National Laboratory, 2024
- Detroit unveils wireless EV charging roadway Construction Dive, 2023
- DARPA program sets distance record for power beaming DARPA, 2025
- China is betting on battery swaps to tackle EV chargers shortage Rest of World, 2024
- World's first dynamic wirelessly-charged motorway shows highly promising real-world results Electreon and VINCI Autoroutes (PR Newswire), 2025
- Arena of the Future brings wireless power to Italy's highways Electreon, 2026
- Nio tops 120 million battery swaps as 4,000th swap station goes live CnEVPost, 2026
- CATL's Choco swap stations top 2,000 as roll-out speeds up CnEVPost, 2026
- Has third rail had its day? Rail Engineer, 2013
- Vinci Autoroutes tests inductive charging while driving electrive, 2025