Saving energy at the airport

Flying has always been a great rush for me. High above the clouds, zooming in and out, reaching fantastic speeds one could hardly ever reach on the ground - Oops, I was dreaming. Flying today is more often a rush to the airport, a perfunctory inspection with Homeland Security, and then boarding the aircraft for that not-so-fast trip to the take-off runway. Out of sight to you and the other passengers are the vital automotive service equipment and crews that prepare aircraft for a safe and almost comfortable flight. Called GSE - Ground Support Equipment - many have the same 4-, 6- and 8-cylinder engines that drive on the highways. Some are gasoline powered, some diesel, and recently some are natural gas or electrically powered.

There are hundreds of busy US airports and hence tens of thousands of GSE vehicles working around the clock to turn aircraft around. GSEs are owned by the airlines and are an expense item they would rather not have. Unlike the aircraft they service, they don't generate any direct revenue. How do the airlines cut their expenses and carbon footprint on GSE?

As is normal, there is no silver bullet to save fuel at the airport gates/apron (the area near the gate), just the obvious:

Proper equipment maintenance
Reduce idling of all equipment when standing by
Switch to renewable energy sources, mainly electricity. Conversion of existing equipment to electricity makes abundent sense because these vehicle barely ever stray from the gate area. They can frequently recharge. No start-up emissions to get things warmed up. No extras noise. Electric vehicles are very efficient internally relative to even a diesel engine and electric motors have high torque at low speeds. GSE vehicles are normally used until their wheels fall off. Something tells me there will be faster replacement as fuel prices remain high.