I must admit to a weakness for motorcycles of whatever kind - including the fossil fuel variety - though, of course, I do believe that electric motorcycles should be the way of the future. This is why this new offering of a diesel engined two wheel drive motorcycle by a Dutch company sounds very interesting to me: http://www.gizmag.com/the-2wd-track-diesel-motorcycle-with-cvt/10636/ For the kind of power and performance that it offers, it should be as fuel efficient as an Enfield Bullet if not better at regular speeds, and, of course, vastly better behaved and capable on the roads. What underlines the bike's "renewable energy" credentials is the fact that it can be ridden on bio-diesel or pure vegetable oil. I'm not sure how really clean either of those options are and I won't even try to go into that. What I will do is check up on this and post back in the future.
Gizmag also has a feature on an LPG driven bike at: http://www.gizmag.com/meet-the-greenfly-the-worlds-first-lpg-motorcycle/10414/ While there have been some dangerous experiments in India with mounting LPG cylinders on scooters and motorcycles, this tech couldbe a really good idea if some Indian motorcycle manufacturer wants to take it up.
Good opportunities, then, for someone who wants to use them. Will someone do this? Here's keeping my fingers crossed.