Hydrogen energy is considered the most promising clean energy source of the 21st century due to its diverse sources, clean and low-carbon characteristics, high flexibility and efficiency, and wide range of application scenarios. Currently, hydrogen metallurgy mainly includes blast furnace hydrogen-rich smelting and direct hydrogen reduction. In blast furnace hydrogen-rich smelting, hydrogen-rich gases—such as coke oven gas and natural gas—are injected into the blast furnace. For every 1 m³ of coke oven gas blown in, approximately 0.6–0.7 kg of coke can be saved, significantly reducing both coke consumption and carbon emissions.
The core technologies of the new coal-to-gas, gas-based shaft furnace direct reduction process include: the preparation and optimization of specially designed oxidation pellets for shaft furnaces, the rational selection of coal gasification technologies, the optimal control of hydrogen-rich gas reduction reactions, and the efficient utilization of energy. Among various coal-to-gas processes, the fluidized bed method stands out for its low investment cost, low oxygen consumption, and high production efficiency, making it a preferred choice when considering equipment features, technical and economic performance, and capital expenditure.
High-temperature-resistant alloy stove pipes are used in the gas heating furnace, which can heat the purified gas to 930 °C, meeting the temperature requirement for the reducing gas in gas-based shaft furnaces. After dust removal, heat exchange, dehydration, and pressurization, the top gas from the shaft furnace is mixed with desulfurized crude gas, decarbonized, reheated, and recirculated back into the shaft furnace to enable gas reuse.
Hydrogen storage methods mainly include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, organic liquid hydrogen storage, and physical solid-state storage using porous materials or metal alloys. Among these, high-pressure gaseous storage and cryogenic liquid storage are the most widely adopted in industrial applications.
Currently, industrial hydrogen production is still dominated by petrochemical-based methods, accounting for over 95% of global hydrogen output. However, these methods generate significant amounts of carbon dioxide. In the near term, it is essential to maximize the utilization of industrial hydrogen by-products and appropriately develop coal-derived hydrogen-rich synthesis gas. For the long-term development of hydrogen energy, in-depth research is needed on scalable, low-carbon, green hydrogen production technologies utilizing biomass resources, wind power, ocean energy, and hydropower.
