Urban Metabolic Analysis of a Food-Water-Energy System for Sustainable Resources Management.

Urban metabolism analyzes the supply and consumption of nutrition, material, energy, and other resources within cities. Food, water, and energy are critical resources for the human society and have complicated cooperative/competitive influences on each other. The management of interactive resources is essential for supply chain analysis. This research analyzes the food-water-energy system of urban metabolism for sustainable resources management. A system dynamics model is established to investigate the urban metabolism of food, water, and energy resources. This study conducts a case study of Shihmen Reservoir system, hydropower generation, paddy rice irrigation of Taoyuan and Shihmen Irrigation Associations, and water consumption in Taoyuan, New Taipei, and Hsinchu cities. The interactive influence of the food-water-energy nexus is quantified in this study; the uncertainty analysis of food, water, and energy nexus is presented.

Tungsten sulfide enhancing solar-driven hydrogen production from silicon nanowires.

Tungsten sulfides, including WS2 (crystalline) and WS3 (amorphous), were introduced to silicon nanowires, and both can promote the photoelectrochemical hydrogen production of silicon nanowires. In addition, more enhancement of energy conversion efficiency can be achieved by the loading of WS3, in comparison with loading of WS2. Polarization curves of WS3 and WS2 suggest that WS3 has higher catalytic activity in the hydrogen evolution reaction than WS2, affording higher energy conversion efficiency in silicon nanowires decorated with WS3. The higher electrocatalytic activity of WS3 correlates with the amorphous structure of WS3 and larger surface area of WS3, which result in more active sites in comparison with crystalline WS2.

Silicon nanowires/reduced graphene oxide composites for enhanced photoelectrochemical properties.

The top of silicon nanowires (SiNWs) arrays was coated with reduced graphene oxide (rGO) by the facile spin-coating method. The resulting SiNWs/rGO composite exhibits enhanced photoelectrochemical properties, with short-circuit photocurrent density more than 4 times higher than that of the pristine SiNWs and more than 600 times higher than that of planar Si/rGO composite. The trapping and recombination of photogenerated carriers at the surface state of SiNWs were reduced after the application of rGO. The results of electrochemical impedance spectroscopy measurements suggest that the reduction of trapping and recombination of photogenerated carriers as well as remarkably enhancement of photoelectrochemical properties can be attributed to the low charge transfer resistance at the SiNWs-rGO interface and rGO-electrolyte interface. The method and results shown here indicate a convenient and applicable approach to further exploitation of high activity materials for photoelectrochemical applications.

Simulation of water quality and plankton dynamics in the Danshuei River estuary, Taiwan.

An ecosystem model was developed to simulate the water quality and plankton dynamics in the Danshuei River estuary, Taiwan. The model simulates the hydrodynamics with a laterally integrated 2-dimensional intratidal numerical model, which supplies the physical transport processes for simulation of water quality and plankton state variables. The application of the model to the Danshuei River estuary indicates that the point source loadings are mainly responsible for the degraded water quality and very high nutrient concentrations in the estuary. The impacts of wastewater discharges are tightly controlled by the transport processes. Frequent occurrence of high river flow and flood events rapidly cleanses the estuary by flushing out both pollutants and plankton populations. The plankton is allowed to grow to significant populations if low river flow lasts for a period much longer than the biological time scale.