Mark.

What Ado was trying to say, in his clumsy northern patois, is that your question is largely irrelevent to current riders of motorbikes.

The pleasure they get from a two-wheeled machine powered by the combustion engine, (nobody says "powertrain, by the way, except researchers and engineers who've never ridden) is inseparable from and totally dependant on the means of propulsion.

The smell, the sound, the actual feel of the engine, makes it what it is.

Take that away and you have nothing.

You probably wont even have a thing known as a "motorbike", as such, in the future non-carbon world.

You're starting at the wrong end : posit the type of energy needed or available for transportation first, then design the vehicle which carries it.

I'd send the project back to your lecturers with a big question mark over it.