A Review of Technical Advances,Barriers,and Solutions in the Power to Hydrogen(P2H)Roadmap

Power to hydrogen(P2H)provides a promising solution to the geographic mismatch between sources of renewable energy and the market,due to its technological maturity,flexibility,and the availability of technical and economic data from a range of active demonstration projects.In this review,we aim to provide an overview of the status of P2H,analyze its technical barriers and solutions,and propose potential opportunities for future research and industrial demonstrations.We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification.Strong evidence shows that an addition of about 10%hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances,and may therefore extend the asset value of the pipelines after natural gas is depleted.To obtain pure hydrogen from hydrogen-enriched natural gas(HENG)mixtures,end-user separation is inevitable,and can be achieved through membranes,adsorption,and other promising separation technologies.However,novel materials with high selectivity and capacity will be the key to the development of industrial processes,and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG.It is also worth investigating the feasibility of electrochemical separation(hydrogen pumping)at a large scale and its energy analysis.Cryogenics may only be feasible when liquefied natural gas(LNG)is one of the major products.A range of other technological and operational barriers and opportunities,such as water availability,byproduct(oxygen)utilization,and environmental impacts,are also discussed.This review will advance readers’understanding of P2H and foster the development of the hydrogen economy.

The opportunity of membrane technology for hydrogen purification in the power to hydrogen (P2H) roadmap:a review

The global energy market is in a transition towards low carbon fuel systems to ensure the sustainable development of our society and economy.This can be achieved by converting the surplus renewable energy into hydrogen gas.The injection of hydrogen(£10%v/v)in the existing natural gas pipelines is demonstrated to have negligible effects on the pipelines and is a promising solution for hydrogen transportation and storage if the enduser purification technologies for hydrogen recovery from hydrogen enriched natural gas(HENG)are in place.In this review,promising membrane technologies for hydrogen separation is revisited and presented.Dense metallic membranes are highlighted with the ability of producing 99.9999999%(v/v)purity hydrogen product.However,high operating temperature(≥300℃)incurs high energy penalty,thus,limits its application to hydrogen purification in the power to hydrogen roadmap.Polymeric membranes are a promising candidate for hydrogen separation with its commercial readiness.However,further investigation in the enhancement of H2/CH4 selectivity is crucial to improve the separation performance.The potential impacts of impurities in HENG on membrane performance are also discussed.The research and development outlook are presented,highlighting the essence of upscaling the membrane separation processes and the integration of membrane technology with pressure swing adsorption technology.