The thing is, if there is a carbon slurry (or other carbon source) going into a direct carbon fuel cell, that is likely to be more power per kg of fuel than water plus aluminum/gallium pellets.

And carbon powder can be created from biomass through direct charcoal conversion, giving very good transportability and stability.

But altogether I'd rather bike to the closest electric train and let the train operator worry about dragging the motors and brakes and all of that around. That way I don't have to park anything in front of the house.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.