Just to reassure you with a final note on this, the study about the total greenhouse effect of every technology is taking care, in the case of electricity, of even the impact of the barrage and the battery recycling from all the cycles. There are greenhouse gases produced by electric buses, but the emissions are very low. The lowest of them all is from the trolley buses, because you have no batteries.
On May 29th, 2012. See this statement in context.