No, electric isn't zero emissions. But it's different emissions. The emissions are moved upstream to the power plant. But this is still an improvement, for a couple of reasons.
The gas powered bike has its lowest emissions when it rolls off the showroom floor. From there, it just gets more polluting, as people rip the smog stuff off, or the smog stuff rots. I mean who are we kidding - does anyone EVER do anything to their exhaust that makes it less polluting? No - the only people who ever touch their exhaust, have completely different goals. And rust never sleeps. But the electric bike has no smog stuff to get messed up.
The power comes from power plants that are constantly being updated with fancy scrubbers and emissions-reducing technology. Because of this, the ultimate emissions of the electric bike will decline over time. And if anyone's going to invest in a bunch of scrubbers and pollution controlling equipment, doesn't it make sense to do that at one big source instead of carrying emissions equipment on a million point sources all over town?
As for whether the grid can support them... when electric vehicles become a big enough power draw, the power companies will offer incentives to shift the demand. Electric vehicle owners will get a plug in their garage that is only live when the demand is lower, and the power will be cheaper there. This isn't new technology - there are already demand shifting schemes like this available in many areas. Here in Michigan people have been using this kind of power for their central air conditioning for at least 20 years. Demand shifting will allow a lot of electric vehicles to charge, without having to increase generating capacity.
The other advantage of the electric bike, is something that's not such a big deal to us, probably, but for Joe Public it's huge. That's the maintenance and storage of the equipment. The electric bike never gets gunky carbs, and the fuel never turns to varnish, even when the bike is stuffed into the back of the garage for the winter and ignored. It's far less likely to need trailering to the dealer for an expensive service in the spring simply because the owner let the carbs gunk up. How many gasoline bikes are ridden for one season, don't start the following spring, and the owner doesn't ever get around to fixing it? There are like-new bikes languishing in garages all over town; we've all seen them when they finally arrive in the classified for fire-sale prices. And this is only getting worse with the stupid E10 gasoline. Also, with no gas in the bike, you can store it indoors without worry about fumes or fire hazards.
Batteries, yeah, they'll have to be replaced eventually. But the battery technology is improving like crazy, lately. Moore's Law is totally in action here. In five or ten years when batteries need replacing, they'll be much cheaper, and better too. I wouldn't worry about the battery replacement costs.
I've ridden a Zero bike. It was very fun. If I was a dirt biker, I'd get one - the dirt application is pretty compelling. Why? Because it's quiet. How many trails are being closed to dirt bikes simply due to the noise? You can roll your eyes at the people who complain about the noise, and say things like "if it's too loud you're too old" but they're not going away. Electric dirt bikes are much less likely to piss off the other users of recreational land.
The range thing is the biggest hurdle, for me. Those numbers that Zero puts out, are insanely optimistic - I bet that in real life the range is about half that. And I like to use motorcycles for traveling. The technology just isn't here yet, to do what I do with a motorcycle, with an electric. But for my driving habits, I would love to get an electric car. Almost everywhere I go in the car, is within ten miles of home, and during riding season my cars sit long enough that they need Sta-Bil. Electric would suit my car driving patterns to a tee. If I lived in one of the states where they sell the Nissan Leaf or the Ford Focus Electric, I'd have tried to get one this year when I had to replace my cage. I usually prefer to buy a new car and keep it until it rots, but this time I bought a used car instead of new, because I hope electric will be available before a new 2011 car would rot.
