Currently, brake dust consists of cellulose fiber particles (organic pad material)...silicon dioxide (the "ceramic" friction material, aka fiberglass) and powdered iron.
Probably all of which can be found naturally in your back yard.
True, but that applies to brake pads regardless of what type of vehicles they are used on. My point was that with regenerative braking, there should be less wearing of the pads, because they don’t have to be used as much.