How fast can California switch from diesel-burning freight trucks to electric big rigs?

In a warehouse in Escondido on a February afternoon, mechanics installed electric motors, drivetrains and batteries in a row of white Peterbuilt freight trucks.

They’re known as “yard goats,” said Joshua Goldman, vice president of sales and marketing for TransPower, one of a handful of companies in California developing electric powertrains for heavy-duty vehicles.