... either would make for a noisy, stinky ride.
Alcohol!
biogas can be stinky, though. This vehicle is so small that it could carry the driver, a biogas bag and little else...
... Are there other easy to produce (at least not requiring a large facility and infrastructure) fuels? Bio Diesel, biogas and biopropane are the only ones I can think of. Or coal...
Not visible(but still took quite a bit of time) is the completely reworked front wheel fork. I replaced the two arms with the rubber booted suspension from the DML Light Infantry Motorcycle. It fit well. I added brake and speed cables and of course, 90% of the work is hidden by the fender...