Converting an vehicle to electric, especially an older model, would be extremely hard and VERY costly. I wouldn't recommend even researching it as it would be extremely difficult to do anyways. My recommendation if you wanted to save on gas and be a better citizen, would be to purchase an electric vehicle as it would be much cheaper than trying to convert your civic into one.
It is certainly not impossible. If you ever take away the transmission clutch of Honda Civic, you will realize that the only thing your car is going to do is spinning flywheel connected to your gas engine against your clutch disc. If you can take a strong electric motor and attach the same flywheel, you can, of course, move your car without any conventional gas engine. This will require custom modification, welding skills, and electrical knowledge will, of course, be required. Motor power, a daisy chain on some enthusiastic electric motor, various rechargeable batteries. Search Google and Yahoo and discover some of the ideas that many people already relieved to relieve gasoline.