Exploring an innovative watershed management approach: From feasibility to sustainability

Watershed management is dedicated to solving watershed problems on a sustainable basis. Managing watershed development on a sustainable basis usually entails a balance between the needs of humans and nature, both in the present and in the future. From a watershed or water resources development basis, these problems can be classified into five general categories: lack of water quantity, deterioration in water quality, ecological impacts, weak public participation, and weak economic value. The first three categories can be combined to make up physical sustainability while the last two categories can be defined as social and economic sustainability. Therefore, integrated watershed management should be designed to achieve physical sustainability utilizing, to the greatest extent possible, public participation in an economically viable manner. This study demonstrates an innovative approach using scientific, social, and motivational feasibilities that can be used to improve watershed management. Scientific feasibility is tied to the nature of environmental problems and the scientific means to solve them. Social feasibility is associated with public participation. Motivational feasibility is related to economic stimulation for the stakeholders to take actions. The ecological impacts, lack of water quantity and deterioration in water quality are problems that need scientific means in order to improve watershed health. However, the implementation of these means is typically not achievable without the right public participation. In addition, public participation is typically accelerated by economic motivation for the stakeholders to use the resources in a manner that improves watershed health. The Big Lost River in south-central Idaho has been used as an illustration for implementing scientific, social and motivational feasibilities and in a manner that can achieve sustainability relative to water resources management. However, the same approach can be used elsewhere after appropriate modifications.     

Fossil fuel sustainability index: An application of resource management

A brief review on use of fossil fuel resources and sustainability is given in this paper. A sustainability index for fossil fuels is developed, which aims to determine the most efficient management of fossil fuel resources for the energy system. The study is conducted for 62 countries, in the presence of independence, lifetime and environmental constraints. The effect of these indicators are then integrated into a single index for oil, natural gas, and coal. Two approaches have been taken. The first one employs equally weighing of each index, where the second one weighs the indices by using principle component analysis. It is concluded that Fossil Fuel Sustainability Index (FFSI) values indicate that countries supporting oil as the one and only major player are condemned to suffer due to incompetent energy policies.     

A step basin type solar water heater-cum-solar still

This communication reports the design details, performance and testing of a step basin type solar water heater-cum-solar still. The combined efficiency of the system is 64.5 per cent.     

Uncertainties and sustainability concepts in biofuel supply chain management: A review

Biofuel energy as an alternative and additive form of energy to fossil fuel has gained much attention in recent times. In order to sustain such a vision, a robust supply chain is of extreme importance in helping to deliver competitive biofuel to the end user markets. In this paper, firstly, an introduction of the evolution of biofuels and the general structure of the biofuel supply chain are presented. Secondly, the three types of decision making levels and uncertainties that are inherent within the biofuel supply chain are discussed. Thirdly, important methodologies for modeling uncertainties in the decision making process are provided. Fourthly, sustainability concepts and models that give perspectives to the social, economical and environmental concepts are reviewed. Finally, conclusions and future research based on incorporating uncertainties and sustainability concepts within the biofuel supply chain are drawn and suggested, respectively.     

Embedding sustainability in the design of water supply and drainage systems for buildings

In addressing sustainability issues for the built environment, focus is often directed towards minimising energy consumption and material use. Often forgotten however, is the potential for the integration of sustainable solutions when designing water and waste management systems for buildings. The fundamental functions of such systems are clearly recognised, but traditional design principles often constrain opportunities for performance enhancement and for water and pipework economies. To an extent, this is unsurprising, given the basic premise that steady-state analysis of flows underpins many of the codes and guidelines used worldwide. However, advances in simulation methods mean that system performance resulting from the use of new techniques and from the integration of innovative and more sustainable design approaches can now be fully assessed.This paper provides an overview of the water supply and drainage systems for buildings whose performance has been assessed through the development, at Heriot–Watt University, of a suite of numerical simulation models. These models accurately predict, using appropriate forms of the St. Venant equations, the pressure and flow regime within such systems by applying the Method of Characteristics finite difference technique. The paper provides three different examples of application, where the focus of each is on embedding sustainability in design.     

Use of waste hot water in double basin solar still

A periodic analysis of a double basin solar still is presented in this paper. In this still waste hot water is fed into the lower basin at a constant rate such as is available from power stations or other industries. The effect of various parameters on the distillate output of the still is also investigated.     

Modelling adaptation of the coal industry to sustainability conditions

Fossil fuels still constitute an important source of energy in the world, but they need to comply with more strict environmental requirements. The coal industry, the basic primary energy supplier to the Polish economy, not only faces new environmental regulations but also restructuring and changes in the industry's organisational structure. The issues of primary importance are the medium and long-term prospects of achieving a suitable quantity and quality of coal supplied, as well as suitable costs. The structure of power generation needs to adjust to emissions limits with given fuel supplies. The paper discusses the construction of a coal supply balancing system which has been developed and applied as a decision support for rational planning of the development of the Polish coal industry. It consists of two linked groups of models: coal supply and coal balancing. Such a structure allows it to respond to the problems emerging for the most part from new environmental regulations, and to select policies that will lead to sustainability in the industry.     

Using strong sustainability to optimize electricity generation fuel mixes

This work represents a contribution to the field of sustainable electricity system design by using an optimization tool to specify the final mix composition, subject to the constraints of: emissions that are within the biocapacity of the region; a diverse and robust electricity supply system; and supply that at least meets current demand. The 25-country European Union (EU-25) is used as a case study. All the goals, save diversity, can be met by re-structuring the current fuel mix, thus maintaining current consumption levels. The diversity target is only met when consumption is reduced by 10–15% and the constraint on maximum material throughput is relaxed. Re-structuring the mix and reducing consumption is insufficient to achieve a sustainable EU carbon footprint. However, the solution proposed singlehandedly allows the EU to meet its Kyoto emissions target as well as its 2007 policy of a reduction of 20% in greenhouse gas emissions by 2020.     

PEM FC with improved water management

Water management problems of proton exchange membrane (PEM)-based H₂/O₂ and H₂/air fuel cell systems (PEM FC) are considered. It is demonstrated that PEM FC performance and efficiency are strongly influenced by water transport phenomena. A new water management scheme, based on anode side water removal, is suggested. It is shown that such a scheme may be very efficient if implementing cathode modified by oxygen permeable liquid perfluorocarbones. Possible efficiency of such a PEM FC is estimated using literature-based parameters of existing practical PEM FC.     

Improvement of water management in polymer electrolyte membrane fuel cell thanks to cathode cracks

The role of cathodic structure on water management was investigated for planar micro-air-breathing polymer electrolyte membrane fuel cells (PEMFCs). The electrical results demonstrate the possibility to decrease, with the same structure, both cell drying and cell flooding according to the environmental and operation conditions. Thanks to a simultaneous study of internal resistance and scanning electronic microscope (SEM) images, we demonstrate the advantageous influence of the presence of crack in cathodic catalytic layer on water management. On the one hand, the gold layer used as cathodic current collector is in contact with the electrolyte in the cracked zones which allows water maintenance within the electrolyte. It allows to decrease the cell drying and thus strongly increase the electrical performances. For cells operated in a 10% relative humidity atmosphere at 30 °C and at a potential of 0.5 V, the current density increases from 28 mA cm⁻² to 188 mA cm⁻² (+570%) for the cell with a cathodic cracked network. On the other hand, the reduction in oxygen barrier diffusion due to the cathodic cracks allows to improve oxygen diffusion. In flooding state, the current densities were higher for a cell with a cracked network. For cells operating in a 70% relative humidity atmosphere at 30 °C and at a potential of 0.2 V, a current density increase from 394 mA cm⁻² to 456 mA cm⁻² (16%) was noted for the cell with a cathodic cracked network. Microscopic observations allowed us to visualize water droplets growth mechanism in cathodic cracks. It was observed that the water comes out of the crack sides and partially saturates the cracks before emerging on cathodic collector. These results demonstrate that cathode structuration is a key parameter that plays a major role in the water management of PEMFCs.     

引水式电站泥沙的分级处理与涡管排沙式沉沙池

根据在山溪性河流上修建引水枢纽引水防沙的经验,提出在立面上多层次防沙排沙与在平面上分级防沙排沙相结合,以达到电站引水渠多引水少进沙的目的,并介绍某涡管排沙式沉沙池的设计思想及运行实践.     

铁路输水管线的运行与管理

本文介绍了当前铁路供水的概况、运行方式,从日常管理中应加强给水设备的检修、处理好给水管线关键部位、重点时期的维护、管道故障及抢修等多方面来讨论铁路管线的运行与管理,从而降低生产成本,走节约化发展道路,有利于其今后以公司制向市场化转制度。     

Optimal water management in small-scale tank irrigation systems

The small-scale tank irrigation system is an effective option for sustainable agricultural water development. The management strategy for water release in such a system is considered in the framework of variational calculus. A minimum principle is deduced to characterize an optimal strategy minimizing a performance index that evaluates water content deviation in the command area and the time when the irrigation tank dries up. The optimal strategies are demonstrated in two practical example systems.     

Model predictive control of water management in PEMFC

Water management is critical for Proton Exchange Membrane Fuel Cells (PEMFC). An appropriate humidity condition not only can improve the performances and efficiency of the fuel cell, but can also prevent irreversible degradation of internal composition such as the catalyst or the membrane. In this paper we built the model of water management systems which consist of stack voltage model, water balance equation in anode and cathode, and water transport process in membrane. Based on this model, model predictive control mechanism was proposed by utilizing Recurrent Neural Network (RNN) optimization. The models and model predictive controller have been implemented in the MATLAB and SIMULINK environment. Simulation results showed that this approach can avoid fluctuation of water concentration in cathode and can extend the lifetime of PEM fuel cell stack.     

Local current density and water management in PEMFCs

We have used computational fluid dynamics analysis to investigate the local current density distribution at the membrane-gas diffusion layer (GDL) interface at average current densities ranging from 0.1 to 2.4 A/cm². A three-dimensional, non-isothermal model was used with a single straight channel geometry. Both anode and cathode humidification were included in the model. In addition, phase transportation was included in the model to predict the distributions of water vapor and liquid water and the related water management for systems operating at different current densities. The dependency of local current density on total water and thermal management of the fuel cell and its other related linkage with physical parameters were investigated. The simulation results showed that at low average current density, the local current density does not vary along the width but gradually decreases along the cell length. However, the opposite trend starts to emerge as the average current density is increased. The anode water activity was found to play a significant role in determining the membrane conductivity and the local current density variation in the cell. Moreover, at high average current density, the local current density in the downstream end of the channel is dominated by the cathode water rather than the membrane conductivity. Specifically, the cathode water accumulates in the shoulder area and congests the pores of the GDL, thereby blocking the passage of oxygen to the reacting area. The resulting scarcity of oxygen in the shoulder area causes a dramatic reduction in the local current density in this region. Simulations using different cathode stoichiometric rates showed that increasing the cathode stoichiometric rate led to better oxygen transportation to the GDL at the shoulder area, and hence improved to smooth the local current density distribution. The model was validated by comparison with the polarization curve (I–V characteristics) in the literature.     

Improvement of PEMFC water management by employing water transport plate as bipolar plate

In this study, a porous hydrophilic water transport plate (WTP) has been employed as a bipolar plate to improve water management in proton exchange membrane fuel cells (PEMFCs). The electric conductivity, gas blocking property, water permeability and wettability of the WTP were characterized. The performance, electrochemical impedance spectroscopy (EIS) and water balance of fuel cells with WTPs and solid plates were evaluated. Benefiting from the humidification and drainage functions of the WTP, the performance of fuel cells with WTPs significantly improved compared with fuel cells with traditional solid plates. As indicated from the experiments, a WTP that was placed on the cathode side is favorable for cell performance and system complexity. Additionally, hydrogen stoichiometry hardly affects the water transport, whereas a decrease in air stoichiometry can switch the main function of the WTP from humidification to water drainage. The results show that the use of WTP technology is promising for water management improvement in PEMFCs.     

Capacity choice and water management in hydroelectricity systems

This paper proposes a simple two-period model that captures the seasonal pattern of water inflows and electricity demand observed in many countries where hydropower is a major source of electricity supply. The model characterizes the effects of different inflows pattern on the optimal water management, capacity, and the associated electricity production and price. The first best capacity is a non-monotonic function of water inflows, which provides a rationale for the observed differences in reservoirs sizes across hydropower systems around the world. The monopoly solution is qualitatively similar to the first best outcome, and the privatization of hydroelectric power generation systems does not always imply a social welfare loss.