Green energy storage devices

Some time ago I learned about energy storage devices. Well I guess to be truthful I have been learning about it my whole life. I would venture to guess that most of you have too. Things like batteries for your cars, rechargeable batteries, etc have more or less become our lives nowadays with all these electronic gadgets we have. But batteries are not the only type of storage devices. As most of you well know energy can either be stored or kinetic energy. And it was thanks to Dr. Hatziadoniu my professor at SIU who introduced me to the concept of kinetic storage devices. See as he said in my class the problem with batteries is you must allow them to charge. You cannot put say 200A on a car battery and get a good charge without blowing the battery to kingdom come. But there is a way to store it in the form of kinetic energy. Take a flywheel for instance, a lot of energy can be stored in one. The only problem is you lose some of that energy through friction of the bearings that are supporting said flywheel. But I believe we now have near perfect electromagnetic bearings if I am not mistaken. Any how here is an article just such flywheel energy storage devices: Energy Storage Devices Link