The interest of those involved in hydroelectricity has been attracted by mini-hydro projects due to their minimal environmental impact and low installation cost. Besides, mini hydros can cooperate with an impressively wide extent of water-related infrastructure, offering a broad potential for investment. In the present chapter, the integrated solution of hydro implementation in water supply systems is presented. Thus, the benefits of a water-supply installation (with constant Q) are extended to energy production. However, defining the optimum operation of such a project is a complicated task, which may involve environmental, hydraulic, technical, and economical parameters. In the present chapter a novel approach is presented, the optimum management of mini hydros in a water supply system with the use of an optimization algorithm (i.e. Harmony Search Algorithm [HAS]). This approach is applied at a site in Northern Greece and is used as a case study of the present chapter.
TopIntroduction
Increasing the non-polluting, renewable energy production is an important aim, for most of the countries, worldwide. European Union (Green Paper, 2001) policy is further emphasized in the “Green Paper” towards a European strategy for sustainable, secure energy supply. The “Green Paper” underlines the potential of hydroelectricity to play a much larger role in both the economy and the energy balance.
Fluctuations in hydroelectricity have a considerable impact on some countries, since they lead to increased coal consumption. The most susceptible to these fluctuations countries in EU are Austria, Sweden, Portugal, Finland, Italy, France and Spain. Large and medium – scale hydroelectric projects rely on hydrological regimes, depending on the seasonal fluctuation. The proposed method, the installation of mini – scale hydros in water networks with a constant flow, answers to the need for stabilization of the energy supply. Besides, recent studies have shown that small scale projects (mini, micro) are the only sector with any prospect in European Union. Furthermore, small hydro established in water systems, has the advantage to exploit the presence of an existing project, reducing construction costs, environmental costs and adds a new environmental and friendly use at the original project, which is the water supply system.
In the present chapter the definition of the optimum capacity and location of mini-scale hydroelectric projects in the presented area, is calculated with the use of Harmony Search Algorithm (HSA). At first glance placing the projects in the existing Break Pressure Tanks (BPT’s), as showed in Figure 1, reduces significantly the construction cost. Hydro units, as a rule, are installed where pressure is released from water lines. However, the created HSA algorithm will investigate the possibility of other alternatives as well. All the technical, economic and environmental data have been included in the created HSA-model in detail.
Figure 1. Hydropower generation in the break pressure tank (BPT)
TopBackground
Hydroelectricity as a Renewable Energy Source
Large – scale hydroelectric plants have as a rule enormous size, having a generating capacity up to several hundreds of MW and supply 20% of global electricity in World. There is still a potential of large hydropower installations in developing countries, but these projects may face financial, environmental, and social constraints. According to Demirbas (2002), the global potential of large-scale hydro which is technically exploitable is estimated to be more than 2200 GW, of which only about 25% is currently exploited.
The term “small-scale hydroelectric projects” usually includes plants with a generating capacity lower than 10MW. Small – scale hydros can be further subdivided into Mini, Micro and Pico hydroelectric projects. Micro hydros usually have a very small generating capacity (<100KW), whereas mini hydros, which are surveyed in the present chapter, have a generating capacity smaller than 1000KW.
Pico hydroelectricity usually is used in rural, isolated communities, in order to cover basic needs. According to a report of the World Bank (2007), Pico hydro is potentially the lowest cost technology for off-grid electrification (see Table 1).
Table 1.
Subdivision of hydroelectric plants
Types of
hydroelectric plants | Generating
capacity |
| Large | >100 MW |
| Small | <10 MW |
| Mini | <1000 KW |
| Micro | <100 KW |
| Pico | <5KW |