09-01-2012, 03:39 PM
Smart Sensor Networks: Technologies and Applications for Green Growth:
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Fields of application of wireless sensor networks:
There are numerous different fields of application of sensor networks. For example, forest fires can be detected by sensor networks so that they can be fought at an early stage. Sensor networks can be used to monitor the structural integrity of civil structures by localising damage for example in bridges. Further, they are used in the health care sector to monitor human physiological data . The following sections outline selected applications of wireless sensor networks.
Smart grids and energy control systems :
Introduction, definition and main components :
Coal power plants are responsible for “nearly 40% of electricity production worldwide”, and electricity generation is thus responsible for a significant share of CO2 emissions (Atkinson, Castro, 2008). To decrease emissions from the energy supply side, alternative clean technologies can be used to generate electricity or energy can be distributed in a more efficient way. In both cases, sensor networks contribute to better and more efficient processes.
On the generation side, sensor networks enable solar energy to be generated more efficiently. Standalone panels “do not always capture the sun’s power in the most efficient manner”. Automated panels managed by sensors track sun rays to ensure that the sun’s power is gathered in a more efficient manner. Such systems can also turn on and off automatically .
On the distribution side, energy is distributed in an often inefficient way in traditional grids. At the time when present girds were planned and extended, they had one single mission, namely “to keep the lights on” . As a consequence, these grids have several shortcomings: many systems are centralised and rely on important central power stations making it difficult to integrate distributed energy resources and microgrids .
They most often only support one-way power flow and communication from the utility to consumers. Further, utilities can barely track how energy is consumed across the grid and, as a consequence, have no possibility to provide any pricing incentive to balance power consumption over time. As utilities can only accommodate increases in demand up to a certain level, they are forced to rely on additional peak load power plants to cope with unexpected demand increases . This is highly expensive and potentially polluting, particularly if plants use fossil fuels .
As demand rises and additional power from distributed resources is fed into the grid, important changes must be made. The smart grid is an innovation that has the potential to revolutionise the transmission, distribution and conservation of energy. It employs digital technology to improve transparency and to increase reliability as well as efficiency. ICTs and especially sensors and sensor networks play a major role in turning traditional grids into smart grids. However, they are only one group of key components of the smart grid. The following section gives an extensive overview of the concept of the smart grid and its key components beyond a pure discussion of sensors and sensor networks as major benefits only arise from the interaction between these components.
Defining the smart grid in a concise way is not an easy task as the concept is relatively new and as various alternative components build up a smart grid. Some authors even argue that it is “too hard” to define the concept . Looking at different definitions reveals that the smart grid has been defined in different ways by different organisations and authors. Table 2 gives an overview of selected definitions. It shows two different approaches to define the smart grid: it is either defined from a solution perspective (“What are the main advantages of the grid?”) or from a components’ perspective (“Which components constitute the grid?”).
From a solution perspective, the smart grid is characterised by:
• More efficient energy routing and thus an optimised energy usage, a reduction of the need for excess capacity and increased power quality and security
• Better monitoring and control of energy and grid components
• Two-way flow of electricity and real-time information allowing for the incorporation of green energy sources, demand-side management and real-time market transactions
• Highly automated, responsive and self-healing energy network with seamless interfaces between all parts of the grid.
From a technical components’ perspective, the smart grid is a highly complex combination and integration of multiple digital and non-digital technologies and systems. Figure 4 provides an overview of the main component of a smart grid: i) new and advanced grid components, ii) smart devices and smart metering, iii) integrated communication technologies, iv) programmes for decision support and human interfaces, v) advanced control systems. These individual grids do not need to be centralised, but can have more control stations and be more highly integrated. The integration of many grids including country-spanning ones provides economic advantages, but there are challenges regarding security if they become too centralised and interconnected.
