A Process Modeling Approach for Water and Energy Optimization in Geologic Hydrogen Extraction

Abstract

Geologic hydrogen has emerged as a promising low-carbon energy vector, but its sustainable recovery requires effective stimulation and production strategies. This study presents an integrated process-modeling framework for evaluating hydrogen extraction from hydraulically stimulated reservoirs. The framework combines fracture propagation, damage evolution, Darcy-scale multiphase flow, permeability–aperture dynamics, and a dual-porosity dual-permeability (DPDP) representation to simulate hydrogen production in fractured source rock systems. In addition to production dynamics, the framework tracks operational water and energy inputs and incorporates a simplified reaction-extent formulation to represent hydrogen generation under data-limited conditions. The model was benchmarked against published shale gas production results to evaluate its ability to reproduce fracture-controlled production behavior and was subsequently applied to a representative multi-well hydrogen development scenario. Simulation results indicate that hydrogen production is strongly fracture-dominated, with fracture pathways accounting for more than 98% of total modeled output. Under the simulated conditions, the system produced approximately 1.13 million kg of hydrogen, with an estimated operational energy intensity of 3.4 MJ/kg H2 and water consumption of 0.02 m³/kg H2. These values represent model-based estimates within the defined operational system boundary and illustrate the potential performance indicators that the framework can generate. Per-well analysis reveals variability in water and energy efficiency across the multi-well system, highlighting the importance of fracture design and reservoir characterization. The simulations also indicate that matrix contributions to total recovery are limited under the assumed conditions, suggesting potential benefits from strategies that enhance matrix reactivity or transport processes. Overall, the framework provides an integrated approach for exploring hydrogen production dynamics together with associated resource requirements. As field and experimental data for geologic hydrogen systems become available, the framework can be further refined through improved parameterization, sensitivity analysis, and calibration to support future technical, environmental, and economic assessments.