Disclosed is a method for backfilling and reconstructing a carbon storage space in an abandoned main roadway and storing CO.sub.2. A surrounding rock of the main roadway is surveyed through geophysical exploration technology, and an anchor bolts (anchor cables) are used to reinforce and support an area which has unstable confining pressure bearing. According to a width and a height of the roadway section of the main roadway, a support formwork is forged in advance, and after the support formwork is placed in the main roadway, backfilling slurry is injected to the periphery of the support formwork. Meanwhile, supercritical carbon dioxide is injected into the backfilling slurry and the roadway, respectively.

The present application is related to a geological carbon sequestration and hydrogen production structure and method based on the spontaneous reaction of water, CO.sub.2, and active minerals, belonging to the field of carbon sequestration and hydrogen production technology. The method comprises the following steps: (1) CO.sub.2 collection; (2) selecting a site for carbon sequestration and hydrogen production; (3) constructing a space for carbon sequestration and hydrogen production; (4) CO.sub.2 mineralization sequestration and simultaneous hydrogen production; (5) hydrogen collection. The method permanently mineralizes and sequesters CO.sub.2 while using the water-CO.sub.2-active minerals reaction for simultaneous geological hydrogen production. It not only reduces the economic cost of CO.sub.2 geological sequestration but also opens a new pathway for in-situ geological hydrogen production, achieving green and low-carbon hydrogen energy production. The geological carbon sequestration and hydrogen production structure is designed to have low sequestration costs and enable large-scale simultaneous geological hydrogen production.

The present disclosure provides a graded underground pumped-storage hydropower system in a coal mine, and construction and methods of use. The system comprises a surface reservoir, wherein multi-stage stepped underground reservoirs are arranged below the surface reservoir, and there is no communication between the multi-stage stepped underground reservoirs. One side of the underground reservoir on each layer is provided with a hydraulic turbine room, and an upward water conveyance passageway and a downward water conveyance passageway are arranged between the hydraulic turbine room and each underground reservoir. Additional water conveyance passageways are arranged between the hydraulic turbine rooms among the layers. During use, the present disclosure can achieve multi-grade power generation and energy storage capabilities by controlling sluice gates, adjusting water flow directions as required.

The present disclosure provides a graded underground pumped-storage hydropower system in a coal mine, and construction and methods of use. The system comprises a surface reservoir, wherein multi-stage stepped underground reservoirs are arranged below the surface reservoir, and there is no communication between the multi-stage stepped underground reservoirs. One side of the underground reservoir on each layer is provided with a hydraulic turbine room, and an upward water conveyance passageway and a downward water conveyance passageway are arranged between the hydraulic turbine room and each underground reservoir. Additional water conveyance passageways are arranged between the hydraulic turbine rooms among the layers. During use, the present disclosure can achieve multi-grade power generation and energy storage capabilities by controlling sluice gates, adjusting water flow directions as required.