i haven't looked into it since 2001 when I was in 1st year engineering, but I know NYC was looking into hydrogen powered buses a few years back (2001) i wonder what they made of it...they were striving to have the cleanest buses running..
http://www.mta.nyc.ny.us/nyct/facts/ffenvironment.htm
and the stats!
The New York City Transit network helps keep cars off the road. Without it, our air would be fouled each year by:
* 22 million pounds of hydrocarbons (causes coughing and chest pains)
* 1.18 million pounds of soot and particulate matter (damages human lung tissue)
* 15 million pounds of nitrogen oxide (causes acid rain and breathing disorders and leads to ozone damage)
* 376 million pounds of carbon monoxide (limits the blood's ability to transport oxygen to body tissue, resulting in headaches, impaired coordination, and death)