The people at Portland International Airport are concerned about the environment too. According to this article PDX is moving towards using alternative fuels. "The Portland International Airport (PDX) in Oregon has become a dedicated user of alternative fuel vehicles in almost every aspect of operation from baggage loading vehicles to shuttle buses, police vehicles, and street maintenance equipment". Alternative fuels like biodiesel play an important role in lowering emission and vehicle longevity.
Go to this blogger post to learn more about what PDX is doing to go green.