Many countries and industries all over the world announced the Carbon Neutrality in 2050. For achieving this target, a high-fidelity innovative combustion simulation should contribute to R&D in both fundamental and industrial applications. In this presentation, a multi-dimensional flamelet modeling and applications of large-eddy simulation (LES) to combustors in novel zero-emission power plants in addition to a coal-ammonia co-combustion boiler in a conventional power plant are presented. Moreover, for a development of a digital twins of real world's clean energy system, the V&V of the super-simulation in which a combustion simulation is coupled with a structure simulation by the unsteady two-way coupling method is reported. The super-simulation is expected as a promised tool to assess combustion performance of designed realistic combustors and reactors with their thermal durability.