FILE - In this May 1, 2013, file photo, an All Electric Bus, a Zero-Emissions Vehicle, produced by China's BYD Co., is parked at the announcement of the opening of an electric bus manufacturing plant in Lancaster, Calif. The California Air Resources Board voted Friday, Dec. 14, 2018, to require that all new buses be carbon-free by 2029. Environmental advocates project that the last dirty buses will phase out by 2040. (AP Photo/Reed Saxon, File) (Source: Reed Saxon)