The aim of this report is to inform about the delivered scientific papers focusing on thermophysical properties of hydrogen-enriched natural gas mixtures with a hydrogen content of up to 20 % injected in the gas grids and hydrogen under geological storage conditions. These were outcomes of the work carried out in Work Package 2 within the EURAMET EMPIR Metrology for Advanced Hydrogen Storage Solutions – MefHySto 19ENG03 project.
This report also addresses the critical need for high-quality thermodynamic data to support the development of advanced hydrogen storage solutions.
Two key applications are explored:
- Hydrogen Injection into Natural Gas Grids: This method leverages existing gas infrastructure for storing and distributing renewable energy from sources like solar and wind converted into green hydrogen. However, accurate equations of state (EoS) are essential to estimate the properties of hydrogen-enriched natural gas mixtures and ensure reliable energy metering.
- Underground Geological Storage (UGS): This approach maximizes storage capacity and allows for reversible storage of hydrogen. Yet, missing data on hydrogen behaviour under high pressures and temperatures hinders the safe and efficient utilization of UGS.
The current reference EoS (GERG-2008) exhibits limitations when applied to hydrogen-enriched natural gas mixtures. This report details research that contributes to overcoming these limitations:
- Published Research: Two peer-reviewed papers have been published, with a third under revision and two more planned for submission. These studies investigate the thermophysical properties of hydrogen mixtures with high accuracy.
- H2 + Natural Gas Blends: The project identified significant changes in phase behaviour with increasing hydrogen content. This reduces hydrocarbon solubility, simplifying hydrogen extraction from UGS. A manuscript on this topic is under preparation.
- Experimental Data: Density measurements were conducted for hydrogen-enriched natural gas mixtures (up to 20% H2) across a range of temperatures and pressures relevant to transportation. Deviations from GERG-2008 were observed and found to be more pronounced at lower temperatures. These findings emphasize the need for further research near the phase boundaries of such mixtures. A scientific paper detailing these investigations is currently under review by a peer-reviewed scientific journal.
- H2-Propane Mixtures: Density data for three hydrogen-propane mixtures were published in the International Journal of Hydrogen Energy, revealing deviations from GERG-2008 that increase with pressure and propane content. Speed of sound measurements were also conducted, but publication was delayed due to various challenges.
- Data Review: A paper published in „Renewable Energy“ comprehensively reviews existing data and models for the thermophysical properties of hydrogen mixtures. The review highlights the need for further data on specific binary systems, like hydrogen with water, hydrogen sulphide, and various hydrocarbons.
The project’s findings provide valuable insights for improving existing EoS models and developing new ones specifically designed for hydrogen mixtures. This will be crucial for the safe and efficient implementation of advanced hydrogen storage solutions, paving the way for a clean energy future.
Report on improved reference equations of state (EoS) used for modelling hydrogen injection up to 20 % vol. including traceable density measurements with a target uncertainty of between 0.03 % to 0.5 % to be used as a basis for accurate determination of calorific values of energy gases
Download report from Aug 2023 (M36)
