The successive energy crises, usually linked to the rising prices of oil, bring about new topics of the energy systems management in general terms. Over all, the electrical system is one of these cases. In addition, a greater concern for environmental issues has introduced, to a greater or lesser extent, the generation from renewable sources in the electrical system. In this context, the possibility of developing and using electricity storage systems would manage mismatches between generation and demand at electricity networks, making them more efficiently. In this research, we propose a number of possible strategies based on technical peak shaving and valley filling. The tool is used as energy storage systems in general terms, regardless of the accumulation technique used. The classification of strategies essentially serves two criteria: optimization service and increased profitability.
Top1. Introduction
Independently of their nature, environmental issues are becoming increasingly important (Marsh, 2005). Especially in developed countries there are several laws, directives or guidelines that must be abided by, in order to achieve the desired sustainability (Daniels & Daniels, 2003). The international efforts in many countries to make commitments in the minimization of pollution must be highlighted, for example the Kyoto protocol (United Nations, 1998). It is based on the climate change and it is reviewed regularly to reflect the reality in terms of the facts that happened (United Nations, 2005) (United Nations, 2007)(The official website of Denmark, n. d.). In this sense, power generation systems are especially significant, whose tendency, as it could not be otherwise, is that the energy input to the power system is originated in renewable resources (MacKay, 2009; Kaltschmitt, Streicher, & Wiese, 2007; Wengenmayr, Bührke, & Brewer, 2013).Thus, it achieves a reduction, as low as possible, of the pollution emissions to the atmosphere from the power generation.
It is important to add that the energy demand usually increases over the time, although in times of financial crises the demand could decrease, as it is shown in Figure 1, and the development of society (Kaltschmitt et al., 2007). In the future, it can be foreseen that this statement continues to be true or even the demand will be increased due to reasons such as the imminent introduction of the electric car (Figure 1) (Warner, 2011; Anderson & Anderson, 2010).
Figure 1. Demand for electricity in Spain (GWh)
In addition to the current trend justified above, two important factors that greatly determine the source of energy in an electrical system must be mentioned:
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Traditional sources are exhaustible and therefore, factors such as the price are becoming less favorable (Rao, 2011).
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Certain types of energy, such as nuclear power, are very difficult to control and, in case of accidents, lead with a huge risk with catastrophic consequences (Ferguson, 2011).
Nowadays, the use of renewable energy sources for electricity generation is unavoidable. Despite the fact that these energy sources have been known for a long time, they are relatively emerging in the generation of electricity and have a long way to go. One of the most significant drawbacks of these sources is that, they are often available at the moment there is not enough demand to consume, due to the own nature of renewable energy. For example, a lot of wind can blow during the night when the power consumption drops considerably (MacKay, 2009). As an example, a specific real case occurred at a wind farm in Sotavento Galicia is shown in Figure 2.
Figure 2.
Comparison of wind speed (blue - m/s) and production of a wind farm (red - KWh)