On 22 March 2021, an approximately 50 Mm.sup.3 ice-rock avalanche occurred from 6500 m a.s.l. in the Sedongpu basin, southeastern Tibet. The avalanche transformed into a highly mobile mass flow which ...temporarily blocked the Yarlung Tsangpo river. The avalanche flow lasted â¼ 5 min and produced substantial geomorphological reworking. This event, and previous ones from the basin, occurred concurrently with, or shortly after, positive seasonal air temperature anomalies. The occurrence of future large mass flows from the basin cannot be ruled out, and their impacts must be carefully considered given implications for sustainable hydropower and associated socioeconomic development in the region.
The stability of riverbank slopes is crucial in watershed ecology. The morphology and tensile strength properties of plant roots play a significant role in slope stability, which is of great ...importance for the ecological stability of riverbanks. The Jinsha and Yalong River basins are the largest hydropower bases in China and are in the ecologically fragile areas of the dry and hot river valleys, yet fewer studies are available on these basins. Further studies on the growth morphology and root mechanical properties of plant roots in the riparian zone at different elevations have not been reported. Therefore, we selected the dominant species of Cynodon dactylon root as the research subject, analyzed the root morphology, and conducted indoor single-root tensile tests to study its root structure and mechanical properties at various elevations. The results showed that the root morphology of Cynodon dactylon was positively correlated with elevation. Compared to low elevations (L and M), the root length increased by 57.3% and 21.47%, the root diameter increased by 24.85% and 13.92%, the root surface area increased by 93.5% and 67.37%, and the total root volume increased by 119.91% and 107.36%. As the elevation gradient increased, the flooding time decreased, leading to more developed plant roots for Cynodon dactylon. The Young’s modulus ranged from 148.43 to 454.18 MPa for Ertan Cynodon dactylon roots and 131.31 to 355.53 MPa for Guanyingyan Cynodon dactylon roots. The maximum tensile strength, ultimate tensile strength, ultimate elongation, and Young’s modulus of the plant root of the Cynodon dactylon showed a power function relationship with the diameter. The maximum tensile strength increased as the diameter increased, while the remaining properties decreased following a power function relationship. The maximum tensile strength, ultimate tensile strength, and Young’s modulus of Cynodon dactylon were positively correlated with elevation, while the ultimate elongation was negatively correlated with elevation. The results elucidate the influence of elevation on the root morphology and mechanical properties of dominant riparian species. This provides a theoretical basis for managing and protecting riparian slopes in ecologically fragile areas.
A direct evidence of enhanced water molecule splitting by increasing defect concentration in Al.sub.2-xMg.sub.xO.sub.3 hydroelectric cells (HECs) has been elaborated for green electricity generation. ...Existence of F, F.sup.+ and Mg.sup.0 defect centers in nanoporous Al.sub.2-xMg.sub.xO.sub.3 (x = 0-0.5) cell pellets has been confirmed by optical spectroscopy. Increased defect density from ~ 1.45 x 10.sup.15 cm.sup.-3 to 5.4 x 10.sup.16 cm.sup.-3 induced by increasing Mg doping concentration is found to be a key factor to control water molecule dissociation/splitting at alumina surface. Small polaron hopping-assisted ionic conduction for enhanced current density is analyzed by impedance spectroscopy. The maximum, 15 mA, current is obtained in Al.sub.2-xMg.sub.xO.sub.3 HEC for x = 0.5 concentration resulting in 13.5 mW off-load peak output power as compared to 4.95 mW peak output power in pure alumina HEC. A theoretical modeling of Nyquist spectra analyzes ion-solid interaction for real charge transfer process in HEC. Deliberate defect creation in alumina devised for water molecule dissociation at room temperature paves the way to fabricate a facile green electricity generation source in the form of HEC. Al.sub.2-xMg.sub.xO.sub.3-based hydroelectric cell is a very low-cost device to generate green electricity besides providing eco-friendly by-products without use of photocatalytic activity, acid/alkali or electrolyte. Moreover, presented innovative alumina-based HEC would be a big step for mitigating industrial waste consisting of alumina. Graphic abstract Polaron assisted hopping of OH.sup.- ions in the lattice of Al.sub.2-xMg.sub.xO.sub.3 HEC and green electricity generation in the form of V-I plot.
The construction of a surface-frustrated Lewis pairs (SFLPs) structure is expected to break the single electronic state restriction of catalytic centers of P-region element materials, due to the ...existence of acid-base and basic active canters without mutual quenching in the SFLPs system. Herein, we have constructed eight possible SFLPS structures on the Insub.2Osub.3 (110) surface by doping non-metallic elements and investigated their performance as electrocatalytic nitrogen reduction catalysts using density functional theory (DFT) calculations. The results show that P atom doping (P@Insub.2Osub.3) can effectively construct the structure of SFLPs, and the doped P atom and In atom near the vacancy act as Lewis base and acid, respectively. The P@Insub.2Osub.3 catalyst can effectively activate Nsub.2 molecules through the enzymatic mechanism with a limiting potential of −0.28 eV and can effectively suppress the hydrogen evolution reaction (HER). Electronic structure analysis also confirmed that the SFLPs site can efficiently capture Nsub.2 molecules and activate N≡N bonds through a unique “donation-acceptance” mechanism.
This is Part II of two papers evaluating the feasibility of providing all energy for all purposes (electric power, transportation, and heating/cooling), everywhere in the world, from wind, water, and ...the sun (WWS). In Part I, we described the prominent renewable energy plans that have been proposed and discussed the characteristics of WWS energy systems, the global demand for and availability of WWS energy, quantities and areas required for WWS infrastructure, and supplies of critical materials. Here, we discuss methods of addressing the variability of WWS energy to ensure that power supply reliably matches demand (including interconnecting geographically dispersed resources, using hydroelectricity, using demand-response management, storing electric power on site, over-sizing peak generation capacity and producing hydrogen with the excess, storing electric power in vehicle batteries, and forecasting weather to project energy supplies), the economics of WWS generation and transmission, the economics of WWS use in transportation, and policy measures needed to enhance the viability of a WWS system. We find that the cost of energy in a 100% WWS will be similar to the cost today. We conclude that barriers to a 100% conversion to WWS power worldwide are primarily social and political, not technological or even economic.
► We evaluate the feasibility of global energy supply from wind, water, and solar energy. ► WWS energy can be supplied reliably and economically to all energy-use sectors. ► The social cost of WWS energy generally is less than the cost of fossil-fuel energy. ► Barriers to 100% WWS power worldwide are socio-political, not techno-economic.
Climate change, pollution, and energy insecurity are among the greatest problems of our time. Addressing them requires major changes in our energy infrastructure. Here, we analyze the feasibility of ...providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight (WWS). In Part I, we discuss WWS energy system characteristics, current and future energy demand, availability of WWS resources, numbers of WWS devices, and area and material requirements. In Part II, we address variability, economics, and policy of WWS energy. We estimate that ∼3,800,000 5MW wind turbines, ∼49,000 300MW concentrated solar plants, ∼40,000 300MW solar PV power plants, ∼1.7 billion 3kW rooftop PV systems, ∼5350 100MW geothermal power plants, ∼270 new 1300MW hydroelectric power plants, ∼720,000 0.75MW wave devices, and ∼490,000 1MW tidal turbines can power a 2030 WWS world that uses electricity and electrolytic hydrogen for all purposes. Such a WWS infrastructure reduces world power demand by 30% and requires only ∼0.41% and ∼0.59% more of the world's land for footprint and spacing, respectively. We suggest producing all new energy with WWS by 2030 and replacing the pre-existing energy by 2050. Barriers to the plan are primarily social and political, not technological or economic. The energy cost in a WWS world should be similar to that today.
► Replacing world energy with wind, water, and sun (WWS) reduces world power demand 30%. ► WWS for world requires only 0.41% and 0.51% more world land for footprint and spacing, respectively. ► Practical to provide 100% new energy with WWS by 2030 and replace existing energy by 2050.
The main advantage of Transmission Switching (TS) is decreasing the cost function in a power system. Using TS requires a high number of transmission switching in the system, which can cause some ...problems in the long run. These problems include decreased lifetime and failure of circuit breakers (CBs), higher repair and maintenance costs, line outage, increased probability of load shedding, and lower reliability of the system. In this paper, congestion management is utilized in the unit commitment problem constrained to the security with the TS to decrease the number of switching. This methodology will resolve the mentioned problems and improve the overall security of the system. Besides, a grid-connected water-power package is suggested to make relaxation for the line congestion which results in the alleviation of the transmission switching. The proposed water-power system is restructured regarding the fuel cell based renewable resource considering the hydrogen tank. Indeed, such a restructured system utilizes the water grid to generate the hydrogen and then power with the aim of linking the electrical grid. Also, on the account of being uncertain of some parameters coming in the electrical grid, an uncertainty-based UT function is addressed to handle uncertainty impacts on the grid's performance. To make awareness-raising, we carry out an outage of the generators as a different contingency scenario of the problem. Finally, the introduced model is testified on two 6-bus and 118-bus grids and solved by Bender's decomposition method. The simulations are performed in GAMS software to confirm the introduced approach effectiveness. Inferred from the results that the proposed strategy can help the grid operator lessen the line congestion up to an acceptable level.
•Proposing a coefficient congestion-based water-power energy strategy to amend the transmission switching.•Modeling linking energy management for multi-energy demands based on the water-power energy system.•Improving the line congestion during the grid-connected mode.•Representing the UT-based uncertainty strategy to model the high-risk multi-energy demands.
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