The external costs per generated kWh, shows that natural gas fired systems have
lower values than that of petroleum products fired systems. The highest value is for
CSFO (3.8328 cent/kWh) while the lowest value is that of CCNG (0.8749 cent/kWh).
For photovoltaic and wind-energy conversion systems, the external costs per kWh
are 0.1792 and 0.0469 cent, respectively.