The very first eHighway launched in Sweden in 2016. The concept here is the same -- the trucks use pantographs (the pickps on their roofs) to latch on to the overhead cables and draw electricity. Trucks can feed electricity into the grid when they brake, making the system particularly useful if there's ever a jam.

The system won't have a major impact for a while. Just five trucks will run the electrified stretch each day where roughly 10 percent of the road's 135,000 daily vehicles are heavy trucks. That reduced emissions footprint could scale up as more trucks support the system, though, and could encourage trucking companies to go electric knowing that their cargo haulers could drive longer on a charge.