There are alot of green solutions out there
The cheap ones:
- disel cars run on just about any oil all you have to do is filter it (you have to change the gas lines because oil eats trough the standard diesel lines in your car)
- Biodisel can be made out of alot of biowaste that is going to waste as long as the resources are free it costs about 10 cents a liter to make real biodisel not just filtered oil, and biodisel is actually better then real diesel as fare as performance goes
- Electric cars if you dont make allot of mileage and are not a speed freak and its green as long as the electricity is green
- Air cars cars that run on compressed air as long as the electricity is green so is the mode for this transportation surprisingly fast and 400 km on one tank but fast to fill up so not such a problem as electric cars
The less cheap ones and needed in the future
- Growing crops to make biodisel (still cheaper then drilling for the stuff but you have to eat too)
- cars running on natural gas not so green but better then petrol or diesel
Future tech:
-cars running on hydrogen hydrogen is currently expensive if one could produce it cheaply and use green electricity to do so it would be a good alternative to fossil fuels
-The Japanese announced about a year ago that they will make a car that actually "cleans" the environment, i couldn't find out on what principle it will do so but interesting non the less.
As for the energy sources of the future my money is on helium-3 from the moon used in nuclear fusion, a Russian billionaire is planning this he said if the moon was made of gold it would be too expensive to ship it to earth but helium 3 is another story. And of course the standard solar, wind, tidal, hydro, power stations.
As for what the governments can do, public transport of all kinds subway, bus, rent a bike (we just got this in our capital works surprisingly well you buy a card fill it up with cash get to a "bike station " rent it and drop it off at the nearest bike station to your destination) and Eco taxis are becoming more and more popular my guess is the companies save allot on cheap alternative fuel and charge the same as the competition.