Helicopters and other aircraft have not yet been incorporated into green fleet modernization schemes, simply because most public agencies that have participated in programs like Evergreen Fleets do not have aircraft as a fleet component.
However, many large institutions such as port authorities, airports, major corporations (hello, Boeing!) and hospitals do have to take the fuel expenses of their aircraft into account when attempting to reduce their emissions. I had not even considered the impact of aircraft on overall greenhouse gas emissions earlier during this project, simply because of the magnitude of the private car fleet on the equation.
According to Tree Hugger, many passenger airlines have experimented with bio-fuel capable aircraft, although helicopters have not experienced similar attention.
"Australia-based Delta Helicopters is developing what it says is the first biofuel-capable diesel helicopter in the world. Dubbed the D2, Delta claims that the helicopter will use significantly less fuel while getting 30-40% more range per gallon than standard engines." (Inhabitat)
The D2 helicopter would also burn about 70% less fuel per hour than turbine aviation engines. There's just one catch: you have to build the helicopter yourself!
Delta plans to sell the D2 as a DIY kit for farmers in remote areas who already have diesel for use in farm machinery. When fully constructed, the helicopter is worth approximately $200,000.
Whether these helicopters can be re-tooled so that they can be manufactured en masse (or at least constructed in urban industrial settings) remains to be seen. Regardless, this is an important indication that we need to look at the big picture - all forms of transportation by air, land, and sea - when diving into green fleet modernization.