A preliminary site selection system for underground hydrogen storage in salt caverns and its application in Pingdingshan,China

Large‐scale underground hydrogen storage(UHS)provides a promising method for increasing the role of hydrogen in the process of carbon neutrality and energy transition.Of all the existing storage deposits,salt caverns are recognized as ideal sites for pure hydrogen storage.Evaluation and optimization of site selection for hydrogen storage facilities in salt caverns have become significant issues.In this article,the software CiteSpace is used to analyze and filter hot topics in published research.Based on a detailed classification and analysis,a“four‐factor”model for the site selection of salt cavern hydrogen storage is proposed,encompassing the dynamic demands of hydrogen energy,geological,hydrological,and ground factors of salt mines.Subsequently,20 basic indicators for comprehensive suitability grading of the target site were screened using the analytic hierarchy process and expert survey methods were adopted,which provided a preliminary site selection system for salt cavern hydrogen storage.Ultimately,the developed system was applied for the evaluation of salt cavern hydrogen storage sites in the salt mines of Pingdingshan City,Henan Province,thereby confirming its rationality and effectiveness.This research provides a feasible method and theoretical basis for the site selection of UHS in salt caverns in China.

Gleaning insights from German energy transition and large-scale underground energy storage for China’s carbon neutrality

The global energy transition is a widespread phenomenon that requires international exchange of experiences and mutual learning.Germany’s success in its first phase of energy transition can be attributed to its adoption of smart energy technology and implementation of electricity futures and spot marketization,which enabled the achievement of multiple energy spatial–temporal complementarities and overall grid balance through energy conversion and reconversion technologies.While China can draw from Germany’s experience to inform its own energy transition efforts,its 11-fold higher annual electricity consumption requires a distinct approach.We recommend a clean energy system based on smart sector coupling(ENSYSCO)as a suitable pathway for achieving sustainable energy in China,given that renewable energy is expected to guarantee 85%of China’s energy production by 2060,requiring significant future electricity storage capacity.Nonetheless,renewable energy storage remains a significant challenge.We propose four large-scale underground energy storage methods based on ENSYSCO to address this challenge,while considering China’s national conditions.These proposals have culminated in pilot projects for large-scale underground energy storage in China,which we believe is a necessary choice for achieving carbon neutrality in China and enabling efficient and safe grid integration of renewable energy within the framework of ENSYSCO.

Large-Scale Underground Storage of Renewable Energy Coupled with Power-to-X:Challenges,Trends,and Potentials in China

1.Introduction Promoting the green and low-carbon transition of energy systems and constructing a new renewable-dominated power system is essential to achieving carbon neutrality in China[1,2].Furthermore,implementing electrification and hydrogenation strategies to address energy consumption is necessary for a successful energy transition.China’s share of electricity in its total energy consumption is estimated to increase from 26%in 2021 to more than 70%by 2060.

Numerical simulations of supercritical carbon dioxide fracturing:A review

As an emerging waterless fracturing technology,supercritical carbon dioxide(SC-CO_(2))fracturing can reduce reservoir damage and dependence on water resources,and can also promote the reservoir stimulation and geological storage of carbon dioxide(CO_(2)).It is vital to figure out the laws in SC-CO_(2)fracturing for the large-scale field implementation of this technology.This paper reviews the numerical simulations of wellbore flow and heat transfer,fracture initiation and propagation,and proppant transport in SC-CO_(2)fracturing,including the numerical approaches and the obtained findings.It shows that the variations of wellbore temperature and pressure are complex and strongly transient.The wellhead pressure can be reduced by tubing and annulus co-injection or adding drag reducers into the fracturing fluid.Increasing the temperature of CO_(2)with wellhead heating can promote CO_(2)to reach the well bottom in the supercritical state.Compared with hydraulic fracturing,SC-CO_(2)fracturing has a lower fracture initiation pressure and can form a more complex fracture network,but the fracture width is narrower.The technology of SC-CO_(2)fracturing followed by thickened SC-CO_(2)fracturing,which combines with high injection rates and ultra-light proppants,can improve the placement effect of proppants while improving the complexity and width of fractures.The follow-up research is required to get a deeper insight into the SC-CO_(2)fracturing mechanisms and develop cost-effective drag reducers,thickeners,and ultra-light proppants.This paper can guide further research and promote the field application of SC-CO_(2)fracturing technology.

Advances in subsea carbon dioxide utilization and storage

Decisive steps in innovation and competitiveness are needed to meet global greenhouse gas emissions and climate goals.As an effective method for reducing carbon emissions,carbon dioxide(CO_(2))storage and utilization on the seabed enable the transport of captured CO_(2)via pipelines or ships to permanent storage sites,such as saline aquifers or depleted oil and gas reservoirs in subsea sediments,or by injecting CO_(2)for the replacement and displacement of subsea resources(oil,gas,gas hydrates,etc.).Subsea CO_(2)utilization and storage(SCUS)involves several research hotspots worldwide,including international and local laws and regulations,security,economics,environmental impact,and public acceptance.Its current research and engineering progress are also of great interest.In addition,the vigorous implementation of the energy transition and the rapid development of renewable energy sources globally have resulted in significant advancements in SCUS.This paper provides an overview of carbon dioxide storage and utilization mechanism in the seabed,analyzes key technical and economic issues,and summarizes existing research on safety risks,monitoring technologies,and investment and operating cost control to identify remaining knowledge gaps.This is followed by an overview of global engineering practice to update on current progress.Finally,combined with the actualities of China,the potential and trend of China's seabed carbon storage and utilization are summarized.This review demonstrates the enormous development prospects for seabed carbon storage and utilization,although some risks remain including leakage and contamination,with which innovation in monitoring technologies and the self-sealing effect of gas hydrate,safe subsea utilization and storage of CO_(2)can be achieved.Additionally,considering the development of renewable energy and the demand for large-scale energy storage,hydrogen,ammonia,or other energy carriers and carbon dioxide storage and utilization can be coupled into an industrial chain to form an economically competitive carbon geological storage mode.