The methanation process is discussed as one way to chemically store renewable energy in a future energy system. An important criterion for its application is the availability of compact, low-cost reactor concepts with high conversion rates for decentralized use where the renewable energy is produced. Current research focuses on the maximization of the methane yield through improved temperature control of the exothermic reaction, which attempts to avoid both kinetic and thermodynamic limitations. In this context, traditional manufacturing methods limit the design options of the reactor and thus the temperature control possibilities. The use of additive manufacturing methods removes this restriction and creates new freedom in the design process. This paper formulates the requirements for a novel methanation reactor and presents their implementation to a highly innovative reactor concept called ‘ADDmeth’. By using a conical reaction channel expanding from Ø 8 to 32 mm, three twisted, expanding heat pipes (Ø 8 mm in evaporation zone, Ø 12 mm in condenser zone) and a lattice structure for feed gas preheating and mechanical stabilization of the reactor, the design explicitly exploits the advantages of additive manufacturing. The reactor is very compact with a specific mass of 0.36 kg/kW and has a high share of functional volume of 52%. The reactor development was accompanied by tensile tests of additively manufactured samples with the used material 1.4404 (316 L), strength calculations for stability verification and feasibility studies on the printability of fine structures. Ultimate tensile strengths of up to 750 N/mm² (at room temperature) and sufficiently high safety factors of the pressure-loaded structures against yielding were determined. Finally, the paper presents the manufactured bench-scale reactor ADDmeth1 and its implementation.

The path to European climate neutrality by 2050 will require comprehensive changes in all areas of life. For large industries such as steelworks, this results in the need for climate-friendly technologies. However, the age structure of existing steelworks makes transitional solutions such as carbon capture, utilization and storage (CCUS) necessary as short-term measures. Hence, a purposeful option is the integration of technical syntheses such as methanation into the overall process. This work summarizes hydrogen-intensified methanation experiments with synthetic steel gases in the novel additively manufactured reactor ‘ADDmeth1’. The studies include steady-state operating points at various reactor loads. Blast furnace gas (BFG), basic oxygen furnace gas (BOFG) and three mixtures of these two gases serve as carbon sources. The methanation achieved methane yields of 93.5% for BFG and 95.0% for BOFG in the one-stage once-through setup. The results suggest a kinetic limitation in the case of BFG methanation, while an equilibrium limitation is likely for BOFG. There is a smooth transition in all respects between the two extreme cases. The reaction channel inlet temperature ${\vartheta }_{in}$ showed a large influence on the reactor ignition behavior. By falling below the threshold value, a blow-off occurred during experimental operation. By means of a simulation model, practical operating maps were created which characterize permissible operating ranges for ${\vartheta }_{in}$ as a function of the gas composition and the reactor load.

Hydrogen from biogenic sources is central to the transition to a carbon-neutral energy system, offering flexibility for mobility and industrial applications. Decentralized steam reforming of biogas enables on-site hydrogen production but requires precise heat management due to its strongly endothermic nature. In small-scale systems, conventional manufacturing approaches often limit geometric flexibility and thermal integration, whereas additive manufacturing enables highly integrated reactor structures that overcome these constraints. This study presents the development and experimental evaluation of a compact, monolithic reformer additively manufactured from silicon-infiltrated silicon carbide, combining combustion and reforming zones in a single component to enhance heat transfer and compactness. The reactor features an internal U-shaped reforming channel filled with a nickel-based catalyst and was tested under varying loads. CH₄ conversions of 95–99% close to equilibrium were achieved at gas hourly space velocities up to 75,000 h⁻¹. Stable internal heat supply sustained reforming, although combustion results remain preliminary due to manufacturing-related blockages in the combustion channels, as revealed by computed tomography (CT) analysis. Energy assessments indicate that thermal efficiency is primarily limited by external heat losses of up to 46%, resulting from the high operating temperatures and small reactor dimensions. The results demonstrate the feasibility of the integrated reactor concept while highlighting current limitations related to manufacturability and heat losses, providing a basis for future optimization and scale-up.