一篇英文文献

Exploring the Potential of Micro Hydropower Systems in Urban Water Supply Systems.Decision-Making and Optimum Management Using Harmony Search.Ioannis KOUGIAS, Thomas PATSIALIS, Antigoni ZAFIRAKOU, Nicolaos THEODOSSIOU Department of Civil Engineering, Aristotle University of Thessaloniki, Greece, yannis.kougias@, patsialis@civil.auth.gr azafir@civil.auth.gr, nictheod@civil.auth.gr Abstract:EU’s strategy towards hydropowe r energy production has turned to support small-scale hydroelectricity. According to the 2012 EEA’s report, forthcoming EU policies in order to promote hydropower must be compatible with the WFD, minimizing the ecological impacts. This explains why the interest of those involved in hydroelectricity has been attracted by micro projects. Typically micro hydroelectricity refers to hydro-plants with a power capacity less than 100kW. Their main advantage is the negligible environmental impact in conjunction with a low installation cost. Moreover, the produced energy is low-voltage electricity. Thus, the produced energy can be either directly consumed or be directed to the National Grid, with a connection cost 4-5 times lower, compared to medium voltage. Micro hydros cooperate with various existing water-related infrastructure, offering a broad potential for investment. In the present paper the integrated solution of micro-hydro implementation in a water supply system is presented. Thus, the benefits of the network (with a constant water supply) are extended to energy production. Decision making and planning of such a project is complicated, involving environmental, hydraulic, technical and economical parameters. The optimum management of an application in Greece is presented, using Harmony Search Algorithm (HSA), a novel optimization technique. After a brief description of HSA, the generated model is presented in detail. By presenting the optimal solutions of the model, we prove that micro hydroelectricity can contribute much more in both the economy and the energy balance.European Union’s policy for sustainable, secure energy supply is emphasized in the Green Paper (2003), which underlines the potential of hydroelectricity to play a very important role in both the economy and the energy balance. In addition to that, increasing the non-polluting renewable energy production is an important goal for the EU countries. EU has set ambitious climate and energy targets for 2020, known as “20-20-20” targets. The three k ey objectives for 2020 include a 20% reduction in EU greenhouse gas emissions from 1990 levels, an increase of the share of EU energy consumption produced from renewable resources to 20% and a 20% improvement in the EU's energy efficiency. The Renewable Energy Directive (2010) defines the national targets of the Member States for raising the share of renewable energy in their energy consumption by 2020. These targets reflect Member States' different starting points and potential for increasing renewable production and range from 10% (Malta) to 49% (Sweden). According to European Commission the national targets will enable the EU to reach its 20% renewable energy target for 2020. This percentage is more than double compared to the 2010 level (9.8%). These targets will also help to reduce greenhouse gas emissions and reduce the EU’s dependence on imported energy.Key words: Micro-scale hydropower, renewable energy, water management, optimization, harmony search Advantages of Small – Scale Hydroelectric ProjectsMicro hydros include projects with a capacity between 10KW and 100KW. Initially these projects have been constructed in the flow of the stream without the need of water storage. Because of their many advantages, the number of installations has considerably increased recently. Their negligible environmental impact and their low installation cost have attracted the scientific and invest ing interest. Besides, the total cost of a Micro Hydro installation is less than 200,000€. Thus,they comprise a tempting investment opportunity for individuals. According to the British Hydropower Association (2005) the advantages that these projects have over other renewable energy sources (RES) are:High efficiency (70–90%).A higher capacity factor (typically CF >45%) compared to other RES.For Solar Panels CF = 10– 30% while for Wind Turbines CF = 20 –30%.Predictability of the energy production.Gradual change of energy production.Hydroelectric generators’ quick response to changing conditions.Micro –hydros in streams don’t include dams and water storage.Micro – hydro systems in streams have good correlation with demand i.e. the output is maximized during winterIt is a long-lasting technology. Systems can be engineered to last for more than 50 years, with a low maintenance cost. Moreover, no significant reduction of their energy efficiency occurs with time.7. CONCLUSIONIn the present paper the installation of micro – scale hydropower in existing water supply systems has been presented. This practice, which has already been successfully followed in several countries, has been enhanced with the use of a modern optimization technique, Harmony Search Algorithm. The economical efficiency of such installations is in many cases certain, since the main items of the system (pipes and storage tanks) have already been built.Thus, the cost of the investment is significantly decreased. Moreover, since the drinking water supply systems have a continuous operation, the installed hydropower plants operate with no interruption during the year. This explains why such installations have one of the highest capacity factors among renewable energy sources. Harmony Search Algorithm has already been effectively used in various water related problems. In the present paper, this novel metaheuristic Algorithm has led to the best possible selection of turbine installations, leading to an optimum management in terms of technical and economical benefit.探索微水电的潜力系统在城市供水系统。