Personally I think that taxing/penalising people who use more electricity / petrol / some other scarce commodity is a poorly thought out tactic, or one where the real motive is actually profit..
If you really want to be proactive a much better solution would be to offer tax rebates to people who make use of power saving bulbs and so on..
For example someone (like me

) who chooses to use a motorcycle for transport could receive a certain rebate on their income tax or something like that..
This way you would actually be encouraging people to make use of energy saving bulbs or more economical vehicles and stuff like that..
Penalising people who's monthly electricity usage exceeds certain amounts will not have the same effect, for example a single guy staying in a small "bachelor flat" all on his lonesome might be leaving his lights burning all the time but because his general usage is so low he will not appear as a "waster", whereas a large household that never leaves lights burning unnecessarily and so on, might still be labeled as "wasters"..
Note: I'm actually against this sort of thing as well as it would be open to plenty of misuse, but I think that nonetheless it would be a better solution than the penalising one..