(425j) Unlocking Hydrogen End-Use Applications Using Separation Technologies

Green hydrogen is pivotal for decarbonization of various industries. To expand the access of green hydrogen to unconventional end-uses such as passenger vehicles, maritime operations, and building heating, it is important to leverage existing natural gas distribution infrastructure. Hydrogen blending in natural gas can help leverage the existing infrastructure. However, this approach would require on-point separation technologies to deblend the hydrogen from natural gas.

In this study we explored membrane-based separation technologies for hydrogen deblending. A membrane model was made through Aspen Custom Modeler and simulations were run in Aspen Plus for a H₂/CH₄ blended system. Effect of pipeline pressure, stage cut, feed hydrogen composition was seen on three important metrics: purity, recovery and area. The analysis indicated that deblending H₂ concentrated streams from transmission pipelines using a cascade of membrane-units is effective.

Material discovery for membranes is often incentivized by the permeability–selectivity tradeoff – these incentives were assessed by comparing performance of 80+ materials (both commercial and novel materials in the literature). They were tested for deblending application and their performance was compared on the purity, recovery and area metrics. It was seen that for a constant stage cut, the area of the membrane was directly correlated with the permeance of CH₄ and the purity was highly correlated with the selectivity – showing an asymptotic behavior.

Costs for membrane-based deblending were also estimated. Assumptions were made on the basis of cost of material and lifetime of membranes. Operational costs including costs of compression were considered. It was hypothesized that the primary cost driver for membrane-based systems will relate to material costs, as the operational costs will be minimal given the pressurized transport of gases in the pipelines. However, these costs become comparable in multi-stage systems that require additional pressurization steps.

Optimization of these systems provided insights into using membrane-based separation technologies for hydrogen deblending linked to different end-use applications.