Milk bottles. I remember the milk marketing board (or something similar) running an ad that said, "What's all this talk about being green? You've been recycling our bottles for years." Didn't last. But why are we trying to recycle carrier bags, when it's the packaging in general that should be standardised and easily cleanable?
Taxiing. Currently when flying into the UK, you bounce off the runway a couple of times, slow down, and turn onto a taxi-way. Then you make your own way to your stand, using engines that are designed to give enough thrust to lift you off the ground by pushing against not-a-lot. In contrast, when you're going in the reverse direction, you're pulled backwards off the stand by a truck. I don't know whether this is because jet engines aren't designed to generate sufficient reverse-thrust, or whether it's because they can, but it's considered impolite to blow in the windows of your departure lounge. Either way, the point is: that truck's got a much-less-impressive engine that burns a different fuel, because it's only going horizontally, and it's got the ground to give traction. So why don't we tow planes around the entire airfield, and only kick in the jets when moving onto the runway? I'm told that that's what they already do, in Australia.
watervole, the floor is now yours.