You can use a small black hole for mass transmutation of lighter elements (like all that surplus hydrogen just sitting idly in your local gas giants or star) in

You can use a small black hole for mass transmutation of lighter elements (like all that surplus hydrogen just sitting idly in your local gas giants or star) into much more useful heavier elements (metals, carbon, oxygen, etc.): https://www.orionsarm.com/eg-article/464790d2497de https://www.orionsarm.com/eg-article/464790d2497de The extreme temperatures and pressures in the accretion disk are basically used to fuse the lighter elements together into heavier ones, which are then pulled out by machinery in close orbit.