Electric buses in the UK have been charged with diesel generators and there was a bit of an uproar about it at first, but a large static diesel generator runnin

Electric buses in the UK have been charged with diesel generators and there was a bit of an uproar about it at first, but a large static diesel generator running at a constant speed can be more efficient than multiple stop/start diesel engines, and therefore more friendly to the environment. Usually seen as a stop-gap until they can get the power upgraded in the depot to support multiple charging buses.