Hydrogen: A seemingly simple fuel by Prof. Heinz PITSCH

Chemical energy carriers will play an essential role for future energy systems, where harvesting and utilization of renewable energy occur not necessarily at the same time or place, hence long-time storage and long-range transport of energy are needed. For this, hydrogen holds great promise. Its utilization by combustion-based energy conversion has many advantages, e.g., versatile use for heat and power, robust and flexible technologies, and its suitability for a continuous energy transition. However, combustion of hydrogen is very challenging. High temperatures lead to emissions of nitrogen oxides and high burning velocities and low flammability limits to potential flash-back and safety issues. Further, intrinsic, so-called thermo-diffusive instabilities occur, which can substantially increase burn rates by factor of up to 3-5 (!). Here, we will discuss relevant properties of hydrogen and provide examples for their importance. Further, results from studies on intrinsic instabilities in laminar and turbulent settings will be presented and analyzed.