How solar fuel can save energy?

In Nashville now, we have hybrid public buses. they are quieter and produce less pollution and save on fuel. my question is this: which costs more to supply energy for these buses....electricity or diesel fuel? is the government really saving any money?

• Answer:

  the problem with switching everything to electric is where to get the electricity from. Our current method is by burning fossil fuels which produce pollution. so in order to truly reduce the pollution we need to switch our ways of getting electricity. So i don't think the government would be saving any money because it is simply going to the same place the same amount thats why electric cars aren't going to be viable until our main way of obtaining electricity is clean (solar, wind, currents etc)