Domestic coal offers the potential for reaching secure inexpensive sources of fuel for at least many hundreds of years but only if new technologies are used to extract and utilize this energy resource in ways that protect the environment. Breakthroughs in clean energy can provide benefits to the economy, security, environment, and jobs. Energy research and advancements will be revolutionized by simulation‐based science. Exascale simulation science offers the potential for not only discovering new technologies but for more rapidly implementing new inventions at a scale sufficient to displace or augment existing energy options. This work supports code development for enabling full machine utilization (CPU and GPUI) of the largest possible Large Eddy Simulations for oxy‐coal boiler modeling. The outcome of this project will be an important step towards enabling petascale simulated guided design for next-generation oxy‐coal boilers for clean energy.