Circular economy applied to methane production from natural gas hydrate reservoirs: potentialities of residual dust coming from steel plants

Natural gas hydrate represents one of the most promising solutions to answer to the constantly increasing energy demand; in addition, the possibility of recover methane via carbon dioxide injection, with a theoretical exchange ratio equal to 1, makes it a potential carbon neutral energy source, which might act as leading parameter toward an energetic scenario completely dominated by renewable energy sources. However, some topic issue needs to be solved to make such resource feasible for large-scale industrial applications. Among them, energetical costs associated to practical operations in marine deposits. The use of chemical inhibitors and or promoters to improve the exchange process is gaining increasing interest and researchers are mainly focused on finding less environmental unfriendly additives and on reducing their costs. In that direction, the present work deals with the possible use of waste dust, produced during steel mill processes, as promoter of the CO2/CH4 replacement process. Those sands commonly contain a great variety of compounds, such as metal oxides, alumina, salts, and so on. Some of them have a chemical composition close to well-known hydrate inhibitors/promoters. Moreover, those wastes, otherwise destined for landfill disposal, could find application as starting materials for further innovative energetic cycle. In this work, both methane and carbon dioxide hydrate formation were tested in absence and in presence of cupper oxides, with different concentrations. Hydrate formation and dissociation results where then compared among each other and with hydrate equilibrium values for those compounds, previously verified and available elsewhere in literature.