The optimal positioning of wind turbines plays an important role in acquiring the anticipated output power from wind farms. This paper addresses challenges related to typical restriction assumptions for turbine arrangements in wind farms with a candidate selection approach. A hybrid quadratic assignment problem-imperialist competitive algorithm (QAP-ICA) method with an initial candidate points' selection (ICPS) approach is applied to two case studies. This hybrid algorithm is used to obtain optimal layout designs in terms of maximum efficiency. The current study incorporates previously utilized indicators from the literature for wind farms, such as wake effects, turbine hub height, rotor diameter, and transmission losses, and proposes additional criteria such as load-bearing capacity of soil and its restrictions. This is done to make the method applicable for realistic cases, and to assimilate the comments of expert designers. The consequence of an optimal layout design can be superior performance with the proposed algorithm compared to previous similar studies. An efficiency improvement of about 4% is attained for the first case considered, and the algorithm provides reasonable optimal wind farm design layouts for the second case, in which reductions of power losses of the wind farm are considered.
Recently, distributed power generation systems especially with renewable sources have shown a promising result all over the world and have been a technical solution to demand growth for electricity. Among these, solar thermal power plants show a trustworthy source for electricity generation especially for rural areas where small scale solar plants are used. Organic Rankine Cycle (ORC) is a suitable means for electricity generation from low grade heat and has shown a good compatibility with parabolic trough solar collectors (PTC). Here, a PTC integrated with an ORC cycle is being investigated for small scale electricity generation near Tehran. The system includes a solar field, a storage tank, and a small scale ORC engine. Performance evaluation has been done by means of commercial software Thermoflex19. Analysis to find the optimal design point turbine pressure and evaporator temperature for obtaining the best performance shows the effect of turbine inlet pressure and evaporator temperature on various cycle characteristics such as net output work, efficiency, solar heat input, oil temperature, collector efficiency and characteristics of heat exchangers such as pinch point and current UA. A comparison of different working fluids is presented. Results show that benzene has the best performance among fluids butane, n-pentane, iso-pentane, R123 and R245fa for the system conditions described.
The electrical energy stored in the batteries of plug-in electric vehicles can be utilized in intelligent house systems to proactively manage electricity energy consumption and costs. The vehicle-to-home (V2H) technology has the potential to provide storage capacity to lower homes' energy costs and provide reliable backup systems in emergency periods. In this paper, the annual cost effects of integrating the electric plug-in vehicles into a hybrid solar PV/wind turbines driven residential district with 10 houses are investigated. These houses are located in Kentucky where both real residential electricity consumption and meteorological data are available. The effects of number of turbines, PV panels and storage capacity on the annual cost reduction were also analyzed. The results showed that for a hybrid system comprising of ten 2kW wind turbines and a 3kW PV array, the V2H technology can save more than 60% of the annual electricity cost.
Numerical simulations of boundary layers play a significant role in the study and interpretation of physical experiments for theoretical explanations of boundary layer disturbances. The influence of thermal boundary layer on the control of heat transport across flat plates is particularly examined. The Crank-Nicolson differential method, which is widely favoured for finite-difference modelling of boundary layer equations, is reviewed. The stability of this method is compared with other numerical approaches in order to establish the appropriate scheme for sustainable applications, involving the design of any conjugate system with heat transfer between the solid and fluid interface. Specific applications to the analysis of cabin comfort in automobiles are anticipated.
Energy supply is currently undergoing a major transition from fossil fuels to more sustainable sources such as renewables and nuclear. However, in the longer term, it is unclear whether these sources will be able to meet demand increases from the developing world, increasing population, and new uses of energy. An estimate is made for the first two of these demand increases based on correlations of the population rate increase and the gap in first and third world GDP. A sustainable world may require more energy to counteract the impacts of climate change, for example, on the supply of clean water and food. Since it is uncertain whether distributed energy sources will meet this demand, new energy supplies might be considered. Some options considered already include more sustainable nuclear systems with use of thorium and fuel recycling, fusion, and large solar projects in orbit, the moon, or in deserts. Previous option analysis of these technologies are reviewed and updated based on current understanding. Potential extensions and approaches are identified for uncertainty estimation, incremental roadmapping, distinguishing serial and parallel technologies, the value of R&D information, and incentive strategies for realizing the economies of scale and learning-by-doing benefits.
This study will compare Canadian and Australian case studies to glean insights and compile lessons learned to better understand how resource development should occur in a way that fosters Indigenous peoples' cultural wellbeing in the present and the future. Both Indigenous populations experienced the institutional effects of European settler state policies, which subsequently engendered forms of social and political colonialism, and both Indigenous populations have had similar experiences with transnational mining companies encroaching on traditional lands as part of a broader process of globalization. We contend that we need a fundamentally different approach to resource development that affects Indigenous traditional lands in both Ontario, Canada, and NSW, Australia; one that takes into consideration the core values needed to sustain Indigenous cultural wellbeing in the present and the future.
Power generation, predominantly coming from run-of-river type hydropower plants, has fallen short of demand in Nepal. The shortage is acute during the dry post-monsoon months, when river flows are at their minimum. Huge amount of fossil fuel is used to generate power during shortages. Large hydroelectric projects are under construction, but many natural and man-made factors have delayed their construction by years. A survey of the measured wind speed, incoming solar radiation and river water discharge at various sites in Nepal has been done. Wind and solar energy potentials have been found to be high during the dry season, when hydropower generation is low. River flow, and consequently, the hydropower generation is high during the monsoon season, at which time wind speed and solar radiation are very low. With a well-planned transmission system, wind and solar power could compensate reduced hydropower generation during the seasons with low water flow in rivers. In the short term, installing wind and solar energy technologies- which have short gestation periods- is observed to be the right choice. Such a power system, with wind and solar power complementing hydroelectricity, has the potential to save capital and reduce carbon emissions for Nepal.
In the present work, the results are reported of energy and exergy analyses of three biomass-related processes for electricity generation: externally fired biomass combined cycle, biomass integrated co-firing combined cycle and biomass integrated post-firing combined cycle. The energy efficiency for the biomass integrated post-firing combined cycle is 3% to 6% points higher than for the other cycles. The energy and exergy efficiencies are maximized for the three configurations at particular values of compressor pressure ratio, and increase with gas turbine inlet temperature. As pressure ratio increases, the mass of air per mass of steam decreases for biomass integrated post-firing combined cycle, but pressure ratio has little influence on the ratio of mass of air per mass of steam for the other cycles. The gas turbine exergy efficiency is the highest for the three configurations. The combustion chamber for the co-firing cycle exhibits the highest exergy efficiency and that for the post-firing cycle the lowest.
Biomass energy and especially biofuels produced by biomass gasification are clean and renewable options for power plants. Also on hot days the performance of gas turbines decrease substantially and fog cooling is a useful method for mitigating this problem. In the present paper, a biomass-integrated fogging steam injected gas turbine cycle is analyzed with energy and exergy methods. Increasing the compressor pressure ratio is observed to increase the air flow rate in plant but to reduce the biomass flow rate. Also increasing the gas turbine inlet temperature decreases the air and biomass flow rates. By increasing the pressure ratio the energy and exergy efficiencies increase, especially at lower pressure ratios. Increasing the gas turbine inlet temperature increases the both efficiencies. Overspray increases the energy efficiency and net cycle power slightly. The gas turbine exhibits the highest exergy efficiency of the cycle components and combustor the lowest. A comparison of the cycle with similar cycles fired by natural gas and differently configured cycles fueled by biomass shows that the cycle with natural gas firing has an energy efficiency 18 percentage points above the biomass fired cycle and that steam injection increases the energy efficiency about 5 percentage points relative to the cycle without steam injection.
Neighbourhood scale sustainability districts are coming to serve a growing role in urban sustainability strategies (Barton 2000; Barton et al. 1995; Taylor 2000; Winston 2009; Jabareen 2006). In modern times, efforts to construct sustainable alternative neighbourhood scale developments date back to isolated voluntary initiatives in 1970s Europe and the United States. In the past decade, however, ecodistricts, écoquartiers, eco-cities, zero/low-carbon/carbon-positive cities, ecopolises, One Planet Communities and solar cities, have become frames – sometimes the dominant frame -- used to justify and orient the construction of new pieces of city in a growing range of countries worldwide (Joss et al. 2013; Chang and Sheppard 2013). This paper documents our work to catalogue such eco-urban developments worldwide. The catalogue we have produced provides evidence that eco-urban developments today are part of a movement toward green global cosmopolitanism (Blok, 2012), but that nonetheless expresses itself in fragmented ways in different world regions. That is, eco-urban developments are being pursued, increasingly, based on standardized models and forms which are coming to redefine relevant and meaningful sustainability efforts in specific economic, political, social and design-based terms. In so doing, they are changing the solution set we associate with sustainable development and even the characterization of the problem of unsustainability at the same time as they change the face of our cities. Our catalogue of eco-urban developments around the world serves as a first step to a deeper understanding of these dynamics and trends at global and regional scales.