Power technologies are usually compared by asking how much their electricity costs. That is no longer enough. Electricity demand is accelerating, driven by data centers, electrification, new factories and cooling. The International Energy Agency expects global data-center consumption alone to more than double to around 945 TWh by 2030—slightly more than Japan consumes today. A power plant that is cheap in 2035 cannot supply a data center that wants to connect in 2028. As demand begins arriving faster than conventional generating capacity,…