Fusion fuel will be close enough to free. Deuterium is less than a thousandth of the hydrogen in water, and there's enough in your morning shower to provide all

Fusion fuel will be close enough to free. Deuterium is less than a thousandth of the hydrogen in water, and there's enough in your morning shower to provide all your energy needs for a year. A liter of heavy water costs about a thousand bucks. For DT reactors, lithium is the other side of the fuel equation, and at the scale we need that's really cheap as well.