Coal will be widely used in the future, so scientists compared different ways to generate power without releasing CO2. They looked at three technologies: ultra supercritical coal combustion, oxy-coal combustion, and integrated gasification combined cycle. They found that ultra supercritical coal is the cheapest for regular power generation, but integrated gasification is better for CO2-free power. Oxy-coal combustion could also be a good option in the future. The costs and performance of these technologies can change based on fuel prices and technology improvements.