Kind of a complicated discussion, but basically, in the US, many cities have been designated as "non-attainment" for certain air pollutants. One of the results of that designation is that governments and certain agencies have to initiate programs to reduce pollutants through the use of various AFV's (alternative fuel vehicles). Airports are included in those agencies that are required to an alternative fuel program.
Link to map of areas designated "non-attainment":
This link is to the Clean Cities web-site, and has a search engine from which people can view the various success stories, as well as various alternative fuel programs at airports.
click on "Airports" under "Category", then click "Select".
Here at MSY
, I'm involved in finalizing a draft alternative fuel cost/benefit analysis that involves all possbile future "stakeholders" including the airlines, shuttle bus/limo's, FBO's, etc, etc, and all possible scenarios for developing anything from a small scale to large scale AFV fueling site.
Tom at MSY
"The criminal ineptitude makes you furious"-Bruce Springsteen, after seeing firsthand the damage from Hurricane Katrina