FedEx in 2014 will begin using 15 electric tow tractors at its air hubs in Oakland, Calif., and Memphis, Tenn., and that have been retrofitted with hydrogen-powered fuel cells subsidized by the U.S. government. The U.S. Department of Energy awarded Plug Power of Latham, N.Y., $2.5 million to modify ground-service equipment as part of its energy efficiency and renewable energy initiatives, the company announced late last year. FedEx will deploy the technology at the...