Electrics are usually powered by nickel-metal hydride batteries, which are recyclable in most places and are less toxic than lithium or nickel cadmium rechargeables. You'll still need to take them to a drop-off site, but—let's face it—you're probably heading to Home Depot, Target, or Wal-Mart sometime this month, anyhow.
While your choice of razor can make a slight environmental difference, the worst thing you can do is shave in the shower, a sin that can be committed with a disposable or a waterproof electric. Shaving for 10 minutes with a typical 2.5 gallons-per-minute shower head, you'd waste more than 24 gallons of hot water, 4.1 kilowatt-hours of electricity, and 5.3 pounds of carbon dioxide in your warm, misty tub. It would take less than three days of shaving to account for the energy you'd use by shaving in the sink for an entire year.
If 14.9 pounds of carbon dioxide keeps you up at night, but you don't want to break any world record for grooming delinquency, there are a couple of odd-ball antique products you might consider. Some clever manufacturers offer hand-cranked razors and units that work by rolling across your face, like a manual lawn mower. If you demand a closer shave than an electric—or a facial-lawn-mower—can provide, turn to the old-fashioned straight-blade razor. You'll still have to rely on water, but a good blade will last for years, and you can even get one secondhand. Plus, your nattering friends will bow to your barbershop cred.