The City of Palo Alto, CA outlawed the use of gas-powered leaf-blowers within the city limits for two seemingly reasonable reasons: they are noisy, and the gas engines used in them are very dirty.[*]
The other day a friend of mine reported seeing a City crew out working with an electric blower on the median of a major street in Palo Alto. So far, so good, right? But: how did he get the electricity? Well of course he was tethered to a 50' extension cord leading to ... wait for it ... a gas-powered 5KW generator. Which is of course noisier than the portable leaf-blowers and more polluting, because it's the same technology yet bigger engine that runs constantly instead of just when the operator is blowing hard.
Not to get into the whole "people shouldn't use leaf blowers" bit, I find these kinds of things hilarious.
/jordan
[*] Here's an article that points out the difficulty of getting the details right before making decisions that feel, in your gut, "right" ...
http://www.encyclopedia.com/doc/1G1-150583316.html