Energy from nuclear fusion is available today – you just need solar panels to capture it.
Nitpick: stellar fusion is fundamentally different from thermonuclear fusion.
Proton-proton fusion is mediated by the weak force [1][2]. A lump of the Sun radiates less power than your body. It works because there is a lot of Sun. Thermonuclear fusion is far more energetic because it's mediated by the strong force.
Or base your DC in a location with lots of other renewable energy
Also makes it easier to fight when it turns evil