There’s a debate over how to make the trucking industry free of emissions, and whether batteries or hydrogen fuel cells are the best way to fire up electric motors in big vehicles. Mr. Schmieder was part of a test of a third alternative: a system that feeds electricity to trucks as they drive, using wires strung above the roadway and a pantograph mounted on the cab.

At one level the idea makes perfect sense. The system is energy efficient because it delivers power directly from the electrical grid to the motors. The technology saves weight and money because batteries tend to be heavy and expensive, and a truck using overhead wires needs only a big enough battery to get from the off-ramp to its final destination.

And the system is relatively simple. Siemens, the German electronics giant that provided the hardware for this test route, adapted equipment that has been used for decades to drive trains and urban street cars.
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