Technology Overview

Hydrogen storage technology plays an important role in modern energy systems, particularly in the context of increasing shares of renewable energy and the need for long-term storage. Hydrogen is a widely available element and has long been used in industries, such as chemicals and oil refining. It is increasingly being considered as a solution for storing surplus energy from renewable sources. With a high gravimetric energy density (120 MJ/kg), hydrogen is suitable for large-scale storage, although its low volumetric energy density requires compression for efficient storage.

Technical Characteristics

Hydrogen storage technologies are classified into two main groups: storage-device-based and material-based methods. Device-based storage includes compression and liquefaction of hydrogen, followed by storage in pressurized tanks, salt caverns, or natural aquifers. For gaseous hydrogen, storage is achieved by compression at various pressure levels, typically below 1,000 bar, using seamless steel or composite tanks.

Underground hydrogen storage is an important solution for future energy systems, with four main approaches: storage in lined rock caverns, salt caverns, aquifers, and depleted oil and gas reservoirs. Each method has its own advantages and disadvantages depending on geological conditions and cost.

Compressed hydrogen storage is currently the most widely used, with four types of pressure vessels: Type I, II, III, and IV, each differing in pressure rating, material, application, permeability, storage duration, and cost.

Type	Operating Pressure (bar)	Material	Application	Permeability	Storage Duration	Cost (USD/kgH₂)
I	<250	Seamless steel, aluminum	Stationary	2.84×10⁻²⁷	Several years	500
II	450–800	Steel/aluminum with fiber wrapping	Stationary, short-distance transport	2.84×10⁻²⁷	Several years	900
III	300–700	Aluminum-lined steel	Mobile applications	1.42×10⁻²⁷	1–3 months	1,500
IV	Up to 1,000	Carbon fiber with polymer liner	Automotive sector	1.42×10⁻²⁷	1–3 months	2,000

Application in Vietnam

Currently, hydrogen storage systems have not yet been deployed at a commercial scale in Vietnam, and applications remain largely at the research and feasibility assessment stage. However, this technology is considered an important long-term solution, particularly for storing surplus renewable energy and supplying fuel to hard-to-electrify sectors such as industry and transport.