they make super capacitors. something that can store electricity like a battery but it only takes seconds to charge.
the fact they can be made this way makes them one HELL of a breakthrough.
the big hurdle to personal power is not windmills, solar panels, generators, hydropower, or hamsters, its consistent output, and power storage.
supercapacitors give you a way to store a lot more of the power made until it is needed. couple it with long term storage units (a buried flywheel, maybe) and your personal 3d printed power source can do wonders.
they can also release all their charge at once (or slowly, either way) releasing all their charge at once means some very cool tricks can be done, even with small cheap ones.