Hydrogen storage in North America: Status, prospects, and challenges

Hydrogen (H2) storage, transport, and end-user provision are major challenges on pathways to worldwide large-scale H2 use. This review examines direct versus indirect and onboard versus offboard H2 storage. Direct H2 storage methods include compressed gas, liquid, and cryo-compression; and indirect methods include physical and chemical adsorption and chemical carriers. In this review paper, we examine these different systems, identifying and discussing challenges related to safe and efficient storage, operating conditions, and applications. Research and development activities related to the economic, safety, and environmental aspects of H2 storage and transportation in North America are also examined in detail. Technically, pressurized H2 storage tanks (350 and 700 bar) have not reached the technical onboard applications target of 0.050 kgH2/L, where tanks' mass, size, and price are critical limiting factors. High specific energy consumption (SEC) and inevitable boil-off H2 losses in liquefaction systems reduce their performance. H2 liquefaction plants can be considered an efficient method for hydrogen storage by reducing energy consumption to less than 6 kWh/kgLH2 and increasing the capacity of liquefaction systems more than 100 t/day. Various studies are ongoing despite the drawbacks of the irreversibility of H2 adsorption/desorption operations (100–400 ˚C), successive cooling and heating cycles, and slow refueling in synthesized metal hydride (MH) systems. Insights and recommendations for H2 storage and transportation in North America suggest short-, medium-, and long-term strategies. Short-term scenarios focus on compressed H2 in light and heavy vehicles, energy consumption reduction in the provision of liquefied H2 for ship and truck transport, and using existing natural gas (NG) transmission infrastructures for H2/NG mixtures (5–20 vol%). Medium-term scenarios address high-volume H2 storage for stationary applications using compressed gas storage in upstream and underground tanks, liquid storage in large, insulated tanks, and higher purity H2 transfer in NG pipelines. Long-term scenarios focus on large-volume subsurface geological storage and basement space use. Additionally, various standards and codes for H2 storage technologies in North America are categorized.