Fusion is relatively easy to achieve. Farnsworth and Hirsch did it back in the 60s and there's a community of people building DIY fusors at home. The hard part

Fusion is relatively easy to achieve. Farnsworth and Hirsch did it back in the 60s and there's a community of people building DIY fusors at home. The hard part is getting the reaction to produce more energy than it requires to sustain. Given a breakthrough that solves that problem, fusion would be a really appealing energy source given the abundance of hydrogen.