Dry Methane Reforming in a Piston Engine for Chemical Energy Storage and Carbon Dioxide Utilization: Kinetic Modeling and Thermodynamic Evaluation

Abstract

The flexible energy conversion in piston engines offers one possibility for storing energy from renewable sources. This work theoretically explores the engine‐based dry methane reforming converting mechanical energy into chemical energy. The endothermic, endergonic reforming process is activated by the temperature increase during the compression stroke, assisted by a reduction of the heat capacity through dilution with argon. This leads to an increase in chemical exergy, as higher‐exergy species are produced with small exergy losses while simultaneously consuming CO2. The engine‐based homogenous dry reforming serves as a flexible power‐to‐gas process and energy storage solution, presenting an alternative to catalytic processes. The piston engine is simulated using a time‐dependent single‐zone model with detailed chemical kinetics, followed by an analysis of thermodynamics and kinetics. With inlet temperatures ranging from 423–473 K and argon dilutions of 91–94 mol%, CH4 and CO2 conversion are between 50%–90% and 30%–80%, respectively, resulting in synthesis gas yields of 45–55%. Additionally, higher hydrocarbons such as C2H2, C2H4, and C6H6 are produced with yields of up to 20%, 10%, and 10%. So, this power‐to‐gas process allows for exergy storage of up to 3.35 kW L−1 per cycle with an efficiency of up to 75%.