High up front costs, for Nuclear fusion/fission, geothermal and solar but cheap fuel, you can run then all day long and sell the power you generate at any price

High up front costs, for Nuclear fusion/fission, geothermal and solar but cheap fuel, you can run then all day long and sell the power you generate at any price to cover the fixed costs and pay off the capital costs and of course you're not generating carbon. With carbon burning generation, the cost of the fuel is volatile, sometimes its cheap sometimes it not, so you have to be clever in buying the fuel and not get stuck just buying spot and going bankrupt because its suddenly spiked in price.