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  • Open access
  • 17 Reads
Fragmenting a Metropolis: Sustainable Suburban Communities from Resettlement Ghettoes to Gated Utopias
Published: 31 October 2013 by MDPI AG in The 3rd World Sustainability Forum session Sustainable Urban Development
The paper examines the impact of the Greater Cairo Master Plan and New Towns Policy on urban housing crisis through some case studies focusing especially on New Cairo City, to the east of downtown Cairo. The empirical research attempts to qualitatively examine the complex reasons for the failure of various policies and implementations in meeting housing needs of middle and low-income people. This has resulted in the emergence of nearly empty new towns, and the increasing fortification of the affluent nouveaux riche within exclusive desert condominiums and gated communities, a phenomenon which aggravated social injustice and housing inequality. These communities’ global architectural styles and marketing strategies are linked to neo-liberal economic policies and private entrepreneurial urban governance related to individualised rights of seclusion, privacy and consumption. Influenced by expatriates in the Gulf monarchies, these desert enclaves are located in Greater Cairo's western desert (6th October City: Dream Land, Gardenia and Beverly Hills) and in the eastern suburbs (New Cairo City: Katameya Heights, Golf City, Al Rehab City, Mirage City, Arabella). Surrounded by golf courses, recreational and commercial facilities, these luxurious residential districts tend to be exterritorial with their construction, maintenance and economies, being largely controlled by international property development firms, whilst locally underlining the ever-sharper social disparity between rich and poor. Whilst exclusive lifestyles and security measures are defining features of these desert resort communities, these gated enclaves do not exist in isolation from their geographical and cultural environments, as noted in New Cairo City. Since 2000 New Cairo City was established as a result of merging Greater Cairo Master Plan's eastern new settlements (1, 3 and 5 ), creating a large suburban community. Initially the area was inhabited by 1992 Cairo's earthquake victims officially relocated to public housing units in settlement (3), which were later regarded incompatible with the development of golf gated communities.To a certain extent, New Cairo City encapsulates most of the features and problems of Greater Cairo’s urban situation, in terms of a hybrid mixture of decayed public resettlement housing for the poor and up-market private gated resort communities for wealthy expatriate groups. New Cairo City, regarded as heterotopian spatial layers with diverse fragmented communities and as venue for new claims by global capital investment, ‘juxtaposes in a single real place different spaces and locations that are incompatible’ (Foucault 1997, p.356). The empirical study adopted a qualitative ethnographic analysis of the on-going contestation between resettled urban poor's right to the city, residents of gated communities, real estate and property speculators and official urban policy. A small area survey was administered within New Cairo City, with in-depth interviews recording narratives of both secondary stakeholder agencies (policy makers, urban planners, NGOs activists, real estate agents) and primary stakeholder groups (urban poor households within resettlement housing and affluent residents within gated communities). The study proposed a stakeholder approach to the sustainable development of new suburban communities in the context of real estate investment and urban planning policies,. Such approach would advocate public– private partnership and grass roots co-operation between home owners, relocated urban poor, land developers, housing experts and local authorities, in order to create inclusive and sustainable urban spaces.
  • Open access
  • 18 Reads
Using Fuzzy Cognitive Maps to Understand the Complexity of the Linkages between Urbanization, Phosphorus Flows and Eutrophication
Published: 31 October 2013 by MDPI AG in The 3rd World Sustainability Forum session Sustainable Urban Development
Phosphorus has been identified as the limiting nutrient and a primary cause of both nuisance and hazardous algal blooms in the North American Great Lakes and other water bodies. Urban areas contributed phosphorus from wastewater treatment plants and through stormwater runoff. Phosphours reduction was the key element of the first Great Lakes Water Quality Agreement, between Canada and the United States in 1972. Although the measures that were enacted to reduce phosphorus were successful at reducing algal blooms, the problem reemerged in the last ten years. The largest hazardous algal bloom on Lake Erie occurred in 2011 and the first hazardous algal bloom on Lake Superior occurred in 2012. Nuisance algae have become a problem for infrastructure and recreation in the nearshore habitats of Lakes Erie and Ontario and to a lesser extent in tthe nearshore habitat of Lake Huron. Fuzzy cognitive mapping (FCM) has been used to describe and analyze theflow of phosphorus through Lake Erie (2009), through agricultural production into Lake Erie (2010) and most recently, through urban areas into Lake Erie. FCM represents the flow and linkages with algal blooms and eutrophication as a network of nodes and linkages. Each node is a driver, a final receptor, or a stressor (a mid-point that both receives and contributes phosphorus to the system). FCM is a modelling strategy that has proven to be very effective for complex systems where data are not available to describe the many processes and flows, yet where an urgent need for action has been established to cope with a problem. FCM is a process where diverse groups of experts work in teams to map out the system. These maps also include weights for each linkage that describe the strength of the linkage, the confidence in the linkage, the scientific certainty, the spatial and temporal extent of the relationship and other relevant factors. The various team maps can then be aggregated into one map through different methods such as averaging the weights or genetic algorithms. A stakeholder workshop was convened in March, 2013 to create several different maps that illustrate the linkages between urbanization, phosphorus, algal blooms and eutrophication. The aggregate maps highlight the multiple drivers and the complexity of the flows through the stressors. Maps might typically contain 90 nodes and 140 linkages. The analysis of the maps provides insight as to the most important nodes in these networks, sggesting where measures to control the flow of phosphorus might have the largest impact. The aggregation and analysis of the maps was done with the Fuzzy Aggregated Linakges Within Environmental Bounds (FALWEB) software, which was developed for fuzzy cognitive maps.
  • Open access
  • 19 Reads
Some Aspects of Sustainable Energy Conversion During Transient Processes in Electric Power Systems Comprising Generator Circuit Breakers
This paper is a sequel to a study by the authors of the electric power systems comprising the generator circuit-breakers (GCBs) at power plant generator terminals. A sustainable assessment of the current interruption requirements of a GCB addresses the main stresses on the generator circuit breaker, revealing that the GCB current interruption requirements are significantly higher than for the distribution network circuit breakers. Hence, generator circuit-breakers are subject to unique demanding conditions caused my specific stresses, namely: high asymmetrical fault currents resulting from high d.c. components of the fault current; greater electrical, thermal and mechanical stresses when interrupting longer arcing time faults; and important dielectric stress after the electric arc extinction caused by the transient recovery voltage (TRV). This paper extends other studies of the authors of the energetic and exergetic transformation chain at the interruption current transient process in an electric power system that comprises the generator circuit-breaker, as well as the transient recovery voltage (TRV) which appears after the interruption of a short-circuit fed by the synchronous generator or by the main step-up transformer. For achieving the TRV equivalent configuration the authors applied the method of operational symmetrical components (o.s.c.), and utilized the operational impedances of synchronous generator and of main transformer, depending on the fault location. Modeling the transient recovery voltage of circuits emphasizes aspects with direct implications on commutation equipment. Thus, the o.s.c. method can be applied at the poles of any breaker, for any eliminated fault type, if the network configuration and elements are known. The TRV, which appears after the interruption of a short-circuit fed by the generator, may be considered like an oscillation, where the oscillation factor and the rising rate (RR) of the TRV are established by the electrical machine parameters: resistance, inductance and capacitance. Consequently, modeling of concentrated equivalent parameters of the synchronous generator at perturbations caused by current interruption transient processes is achieved in this study through an approach based on sustainability concepts. These findings allow for simulations of the transient recovery voltage and comparisons with experimental results.
  • Open access
  • 24 Reads
New Heat Transfer Fluids (HTFs) for Solar Thermal Applications
Heat transfer fluids (HTFs) are used widely in many industrial processes. They collect and transport thermal energy in process heating, metal working, machine cooling with applications in the aerospace, automotive, and marine industries. Also, these fluids comprise one of the key technological components in electricity generation from concentrating solar power systems (CSPs), where they can store thermal energy as a sensible heat reservoir for later delivery to the power conversion system in absence of solar radiation. Here the authors, have developed a new one pot strategy towards biarylated ethers as novel Heat Transfer Fluids while using minimal amount of reaction solvent. The physical properties of these fluids will be discussed and compared to calculated values gained from different computational models. The use of the fluids in Solar Thermal Energy Generation will be indicated.
  • Open access
  • 13 Reads
Energy and Exergy Analyses of a New Combined Cycle for Producing Electricity and Desalinated Water Using Geothermal Energy
A combined cycle for generating electrical power and desalinated water is proposed and analyzed thermodynamically. The cycle, which utilizes geothermal energy, is a combination of the power-producing ammonia-water Kalina cycle, an absorption heat transformer with lithium bromide as working fluid and desalination facilities for removing salt from sea water. A parametric study is carried out to determine the effect of such parameters as the pressure at the turbine inlet, the ammonia water concentration in the transformer and the temperature of the hot water at the evaporator exit, on the first and second law efficiencies as well as on the distilled water flow rate. The results indicate that within specified ranges of these parameters, the energy and exergy efficiencies vary between 16 - 18.3% and 62.64 -69.48%, respectively. Comparing the Kalina and the proposed cycle, it is observed that the first and second law efficiencies are enhanced by around 12% and 24%, respectively, as the absorption heat transformer cycle is added to the Kalina cycle. The proposed cycle could produce 2.94 MW of electrical power and 0.34 kg/s desalinated water by means of extracting 89.3 kg/s of geothermal water at 124 oC from the earth.
  • Open access
  • 23 Reads
An Energy and Economic Analysis of Energy Crops Processing into Bioethanol as a Gasoline Substitute
Two crops, energy cane and sweet sorghum which could be cultivated at marginal lands in subtropical climate (southeast U.S.) were analyzed to determine their potential to be processed into bioethanol as a gasoline substitute. A solution of sucrose and reducing sugars (shortly sugars) separated in the form of "juice" by squeezing those crops is a well known semi-product to be converted into bioethanol by a greatly established in Brazil technology (1G-technology). The residue is called bagasse and consisted of fiber and moisture. Fiber (mainly composed of cellulose, hemicellulose, and lignin) could be employed in the process of its lignocellulosic conversion to make a solution of sugars as an intermediate step in their fermentation into bioethanol. This technology (2G-technology) is yet at a development stage. Bagasse, on the other hand, is an energy carrier required to generate electricity and steam essential for both technologies. The analysis was done for the case when all the necessary energy demand is satisfied by the internally generated bagasse what makes the process of bioethanol production fully renewal and self-sufficient (sustainable). Due to a seasonal character of harvesting and continuous bioethanol manufacturing, the calculated energy balance accounts for sugars storage in the form of their concentrated solution (syrup). The economic efficiency for bioethanol production as a gasoline substitute was determined in comparison with the power generation option in dependence on gasoline and electricity prices meaning that both crops could be combusted to generate renewable electricity. As was shown by the analysis, manufacturing of bioethanol from sugars in "juice" compared to the sugars obtained through lignocellulosic conversion is associated with 2.5-4 times higher economic efficiency. In order to stay competitive with renewable electricity, bioethanol from fiber should include both cellulose and hemicellulose conversion into fermentable to bioethanol sugars. In spite of a higher sugars percentage in the sweet sorghum "juice", the relative selling cost of one tonne of energy cane supposed to be higher due to greater (more than three times) fiber content. The analysis showed that sugars in crops have value about three times higher than fiber; therefore, taking into account this proportion, increasing sugars content at the expense of fiber could be the way to improve quality of energy cane varieties. A greater yield of energy cane also favors a better economic land-use efficiency to produce bioethanol as a gasoline substitute.
  • Open access
  • 21 Reads
Design of a Homogenizing System for Bio-degradable Food Waste from Eatery Centres
Effective pre-treatment of food waste is important to ensure that subsequent treatment in a biogas plant works well. This paper describes a two-dimensional finite volume model for the design of a homogenizing system for bio-degradable food waste from eatery centers. The numerical solver incorporates the analysis of the property distribution for food waste slurry in a storage tank, while coupling the impact of mixing on the slurry fluid. The partial differential equations which describe the conservation of mass, momentum and energy are simulated. The simulation covered the mixing and heating cycles of the slurry. The slurry fluid was exposed to a pretreatment temperature of 600 C. With carrot-orange soup as the studied food waste, constant density and a temperature dependent viscosity are assumed. The predicted results for velocity, pressure and temperature distribution are discussed and a source term for mixing was proposed. This assessment of distribution of velocity and temperature is expected play a role in future studies and designs of a homogenizer for biodegradable food waste.
  • Open access
  • 8 Reads
Exergy Storage in the Ground
There are many systems in use that store heat in the ground. Most store the heat at a low temperature so they require heat pumps to raise the delivery temperature to a useful value, but that consumes power. Some, like the storage systems used for storing solar heat operate at a temperature that is high enough to avoid the necessity of using heat pumps. The latter are storing both the heat and the exergy that would otherwise be required to drive the heat pumps. Concentric ring heat stores can operate with a hot core that eliminates the need for heat pumps for space heating and DHW, and they can also be designed so that they also provide for space cooling, again without using a heat pump for delivering the cooling. That can be accomplished by using a heat pump to extract heat from the outermost ring and transferring that heat to a central ring. In such a design the average temperature of the outer ring over the year is the same as the ambient ground temperature so there is no net heat flow into or from the surrounding ground, but in the summer that temperature will be low enough to provide the cooling and in the winter it will be elevated so the heat pump can deliver a higher temperature at its output. In such a system, the heat pump operates only when excess power capacity is available (it can be operated directly by the grid operator), enabling the grid to handle power excesses from nuclear stations or wind turbines, and it does not consume any power (except a small amount for circulating pumps) during the peak demand periods. Such systems can use the summer air as the energy source, or they can employ waste heat from AC systems, or they can use solar heat, or any combination of these sources. A variant can also use the cold winter air as the source for large buildings that primarily require cooling. Such systems can be designed to achieve net zero energy objectives for both large and small buildings and in individual cases can even achieve net zero electricity consumption. The air is effectively an unlimited energy source so such systems can be scaled up to handle any likely future demands for heating, cooling and DHW. The physical size of the heat stores (and the resulting depth and cost of the boreholes) is quite small because such stores are very energy efficient and the ground between the rings swings through a wide temperature range.
  • Open access
  • 15 Reads
A Methodology to Assess the Sustainability of Energy Systems through Life-Cycle Analysis and Sustainability Indicators
Published: 31 October 2013 by MDPI AG in The 3rd World Sustainability Forum session Environmental Sustainability
Measuring progress towards sustainability is an important step in achieving sustainable development but a standard and universally accepted approach does not yet exist. Here, a sustainability assessment methodology for energy systems is developed with the assistance of life-cycle analysis and impact assessment. System-related parameters are compared to target values to yield dimensionless indicators and sub-indicators that are then aggregated into a composite sustainability index using weighting factors. The proposed sustainability assessment methodology is applied to a wind-battery system designed to meet the electrical energy needs of a small community in Southern Ontario. The new sustainability assessment methodology is expected to prove useful as a tool for understanding and fostering sustainable energy systems, alone or in concert with other approaches.
  • Open access
  • 20 Reads
Artisanal Gold Mining and Mercury Contamination of Surface Water as a Wicked Socio-Environmental Problem: a Sustainability Challenge
Published: 31 October 2013 by MDPI AG in The 3rd World Sustainability Forum session Environmental Sustainability
In this research note, artisanal gold mining and its associated mercury pollution of surface water in West Africa is characterized as a socially complex (wicked) problem wherein stakeholders have conflicting interpretations of the problem and the science behind it, as well as different values, goals, and life experiences. For that reason, policy makers, public policy professionals, and other stakeholders who tackle with this problem must go beyond conventional expert and technical knowledge in order to effectively resolve it. In particular, effective solution may necessarily requires holistic, not partial or linear thinking, innovative and flexible approaches, the ability to work across agency boundaries, increasing understanding and stimulating a debate on the application of the accountability framework, effectively engaging stakeholders and citizens in understanding the problem and in identifying possible solutions, a better understanding of behavioral change by policy makers, and tolerating uncertainty and accepting the need for a long-term focus.