Using rechargeable batteries is the greenest choice, since they can be recharged up to 1,000 times before they lose their ability to recharge. Plus, rechargeable batteries are easily recyclable -- check out the nonprofit Call2Recycle.org for recycling sites. But when shopping for rechargeable batteries, there is a difference. Cheaper nickel-cadmium batteries tend to drain quickly and need to be charged more often. Plus, cadmium is highly toxic. Instead, buy batteries called "NiMH" (nickel-metal hydride). They are rechargeable and do not use cadmium. Plus, NiMH batteries keep their charge longer and have a longer shelf life.