http://news.yahoo.com/toilet-maker-flush-pride-biogas-bike-run-163303508.html

Until you hit that one bump in the road that sends all that stuff back up. Then you have to stop and cleanup. There is always a downside, no matter haw good it looks.

I posted a thread on this a month or so ago. I put a link to the video - very wierd sh!t:
http://www.starbikeforums.com/forums/showthread.php?t=5888&highlight=bio+fuel+scoot