Diffusion and Viscosity of Hydrogen in Geothermal Systems

Hydrogen injected into deep geothermal formations undergoes molecular diffusion and experiences viscous resistance as it migrates through pore networks and interacts with reservoir fluids. The rate at which hydrogen spreads from regions of high to low concentration is governed by its diffusion coefficient, which increases with temperature but is sensitive to fluid composition and pressure. Viscosity, the internal friction that opposes flow, influences both the injection pressure required and the distribution of hydrogen plumes within aquifers or depleted reservoirs. In hot, high-pressure environments typical of geothermal systems, hydrogen may exist in supercritical or near-critical states, altering its transport properties relative to ambient conditions. Geological heterogeneity, mineral surfaces and dissolved salts further modify pathways and retardation factors, leading to complex coupling between diffusion, advection and phase behaviour. Insight into these processes underpins safe and efficient underground hydrogen storage, informs the design of enhanced geothermal systems that co-produce hydrogen, and guides assessment of long-term containment and recovery strategies.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Diffusion and Viscosity of Hydrogen in Geothermal Systems publication trend

The graph below shows the total number of articles in diffusion and viscosity of hydrogen in geothermal systems across all publications each year (not limited to Nature Index journals).

Technical terms

Diffusion coefficient: A measure of the rate at which molecules spread from regions of high to low concentration under a given set of conditions.

Viscosity: The internal resistance of a fluid to flow or deformation, often increasing with density and molecular interactions.

Porous media: A solid matrix containing interconnected voids or pores through which fluids can move.

Tortuosity: A dimensionless parameter quantifying the complexity and winding nature of flow paths in a porous medium.

Cushion gas: A background gas, such as methane or nitrogen, maintained in underground storage to preserve pressure and support injected hydrogen.

Supercritical fluid: A phase above its critical temperature and pressure where distinct liquid and gas phases do not exist, exhibiting unique transport properties.

References

1. Diffusion Coefficients of N2O and H2 in Water at Temperatures between 298.15 and 423.15 K with Pressures up to 30 MPa. Journal of Chemical & Engineering Data (2023).
2. Empirical and Numerical Modelling of Gas–Gas Diffusion for Binary Hydrogen–Methane Systems at Underground Gas Storage Conditions. Transport in Porous Media (2023).
3. Measurements of the Viscosity of Hydrogen and a (Hydrogen + Methane) Mixture with a Two-Capillary Viscometer. International Journal of Thermophysics (2024).