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Pumped hydro energy storage (PHES) can effectively alleviate the renewable curtailment and resource waste caused by expansion of wind and solar-based renewable energy (RE) sources. However, the influences of regional hydrological characteristics, operational characteristics of PHES units, and power supply-demand balance on the regulating effect of PHES have been neglected. In this paper, an improved hybrid power system dispatch model (Dispa-set) that considers regional hydrological characteristics, unit operational characteristics, and RE curtailment penalty is proposed. The potential and limitations of PHES on reducing renewable curtailment and carbon emissions in four Northwest provinces (FNP) during the 14th Five-Year Plan (FYP) are evaluated through 6 sub-scenarios. Studies have shown that increasing PHES can effectively reduce renewable curtailment and carbon emissions, but uncoordinated development of PHES and RE results in resource waste and slows down carbon reduction. For example, a 10% increase in PHES during the 14th FYP could increase renewable curtailment in Qinghai by 1.1% and CO2 emissions in Gansu by 0.05%, due to uncoordinated development, demand for electricity supply, and regulated power sources. Therefore, combining PHES development with regional hydrological and operational characteristics is essential to achieve coordinated development with RE and unlock technology, economic, and environmental benefits. [ABSTRACT FROM AUTHOR]

• Developed the site identification model for pumped storage with different topologies. • Proposed a "regular network structures" criteria system by considering criteria cross. • Proposed a weight calculation method combining eigenvector and weight recursion. • The average annual flow rate evaluation index is proposed for T3 topology PHS. Well-located Pumped hydro storage (PHS) can be a cost-effective solution to complement fluctuating renewable energy generation. Effective PHS site selection will improve the reliability and economic viability of power supply from intermittent renewable energy sources. However, identifying viable PHS sites is challenging due to limitations posed by terrain, land use, ecology, socio-economic hurdles, inconsistent siting principles for different topological configurations. Therefore, this study proposes an efficient, standardized four-phase PHS site identification framework that can detect and rank for different PHS topological sites. Firstly, infeasible areas were eliminated based on exclusion criteria. Secondly, site identification evaluation criterion systems were established for PHS with different topologies through expert meetings and literature review. Then, a site identification model for PHS with different topologies was developed using ArcPy to identify feasible alternative sites. Finally, a spatial multi-criteria decision-making method was used to rank the alternative sites. This study evaluates the potential of PHS with three different topologies in the Northwest China. The results show that there are 994 suitable PHS sites in the Northwest China, with a total energy storage capacity of 2.8 TWh. Topologies T1, T2, and T3 have 34, 843, and 118 PHS sites, respectively. The total energy storage capacity for these topologies is 162.8 GWh, 1979.9 GWh, and 678.1 GWh, respectively. The sites with higher composite scores are largely concentrated in Xinjiang Altay region and the central region of Gansu and the northeastern region of Qinghai. [ABSTRACT FROM AUTHOR]

Pyrolysis is an enabling technology to extend the value chain of coal while reducing its emissions. To improve the product distribution of coal pyrolysis at a reasonable cost, this work explored the utilization of industrial waste-derived red mud modified char (RMMC) and red mud leaching solution (RMLS) for ex-situ and in-situ catalytic coal pyrolysis, respectively. The structural and compositional features of RMMC catalyst and RMLS-loaded coals were revealed by XRD, physisorption, FT-IR, XPS, and Raman spectroscopy. The pyrolysis experiments with RMMC and RMLS were conducted in a two-stage fixed bed reactor and a one-stage fixed bed reactor, respectively. As compared to non-catalytic pyrolysis, RMMC increased the light tar fraction by 28.3 %, dropped the heavy tar yield from 4.4 wt% to 2.0 wt%, and reduced the contents of heteroatoms (O/N/S) in tar significantly at 500 °C. With 0.25 wt% RMLS, the light tar fraction was increased by 21.7 %, and the heavy tar yield was lowered to 2.8 wt%. This work demonstrated the feasibility and potential of RMMC and RMLS-catalyzed coal pyrolysis to empower both coal and aluminum industries. [Display omitted] • Coal pyrolysis volatiles upgrading over RMMC and in-situ catalytic coal pyrolysis with RMLS are demonstrated. • RMMC and RMLS improved light tar fraction and lowered heavy tar yield significantly. • Both RMMC and RMLS increased gas yields by >60 %. • The structural and compositional features of RMMC and RMLS-loaded coals are illuminated. [ABSTRACT FROM AUTHOR]