Furrer + Frey, a provider of rail electrification and rapid charging systems for transport, is proposing tractor swapping as a solution for the electrification of long-haul trucking. Furrer + Frey is a long-time partner of Opbrid, the provider of the overhead pantograph-based ultra-fast charging Opbrid Bůsbaar for buses (earlier post).
At IAA 2014, Opbrid introduced the Trůkbaar for heavy-duty trucks; the Trůkbaar is one element for the Furrer + Frey tractor swapping solution. Furrer + Frey has also acquired Opbrid, and folded it into its operations. (Earlier post.)
In a presentation outlining the concept, Roger Bedell (founder of Opbrid and now onboard with Furrer + Frey), notes that numerous studies suggest that in 2020-2030, heavy-duty vehicles may overtake passenger cars as the largest global contributor to fuel consumption and GHG emissions in the transport sector.
A variety of solutions have been suggested for shifting long-haul trucking to electric drive, including the use of overhead catenaries (earlier post); in-road inductive charging; ultra-fast battery recharging; and battery swapping.
The first two require major investments in infrastructure; the third relies on heavier, lower energy density LTO batteries and ultra-high charging rates; and the fourth is technically difficult, given the size of the battery packs and the need for expensive, dedicated stations, Bedell observes.
Under the proposed tractor swapping model, a tractor-trailer with a low battery charge would pull into a station where a fully charged tractor is waiting. The driver switches tractors, and departs with a full pack. The first tractor then recharges.
Several enabling technologies can streamline the process:
Jost KKS automated coupling system. This is a fully automatic driver assistance system that controls all functions of the coupling and decoupling process that have previously been performed manually. This also includes the first automated interface for pneumatic and electric connections.
Furrer + Frey Opbrid Trůkbaar. The Opbrid Trůkbaar is designed for ultra high power mode 4 DC charging, up to 650 kW. This amount of power transfer uses the conductive technology transferred from the European electric rail industry by Furrer + Frey. This amount of power transfer enables scenarios such as super short charge stops and 24-hour operation.
Although the advantages are clear (simple and fast, without the need for large infrastructure projects), there are a number of disadvantages that need to be addressed Bedell points out:
Need for precise scheduling to avoid idle tractors.
Installation on the KKS system on participating tractors and trailers.
Delays can propagate through the system—similar to delays in air travel.
The business model favors large shippers.
Bedell estimates that the range required per tractor will be about 200 km (124 miles), plus a buffer for wind, hills, etc.
Tractor-trailer electricity consumption is approximately the same as a 12 m bus, or about 1kWh/km. Doubling that (2kWh/km) would result in a pack of about 400 kWh.