Abstract
Sustainability and energy prices make the use of energy obtained from renewable sources on an urban scale and for isolated local facilities necessary for municipal authorities. Moreover, when the demand of energy is at night, as for street lighting installations, the use of accumulative systems is necessary, which means a major drawback due to a short lifetime expectancy and high cost. The use of batteries can require more than 70% of the budget of these lighting systems and has a critical impact in the project. The problem to solve is finding different renewable energy sources that can produce energy throughout the day, especially during the night, at the same time at which it is consumed. As one of the competences of municipal authorities is water supply networks, this paper analyzes the use of energy recovery turbines within these installations as an alternative to photovoltaic generators. To study the viability and effectiveness of this alternative, the water flows available in the network of a medium-size municipality were monitored and analyzed in depth to assess the amount of recoverable energy. In addition, an energy recovery turbine (ERT) station was set up, installing a bypass around one of the pressure-reducing valves (PRV) of the installation where energy is dissipated without practical use. The results obtained imply that the system proposed has economical and technical viability, is reliable and guarantees full service in all the seasons’ conditions. Moreover, the needs of the energy storage capacity are much lower (~8%) than with solar panels.
Highlights
Under this premise of evaluation, the following aspects of the experiment will be discussed: the energy conversion efficiency achieved and evaluation of the suitability of the experimental installation; calculation of the maximum load that can be powered with reliability under the premises of this work and the required battery capacity; the comparison of the proposed installation with its equivalent powered using PV modules, paying particular attention to the additional needs of the energy storage capacity to provide service assurance and the associated costs involved and, the results of extrapolating all the energy that could be recovered from the water distribution facility if the total flow from the main pipeline is derived from the pressure-reducing valves (PRV) and driven into the energy recovery turbine (ERT)
The recovery of the energy that is lost in the PRV of water supply networks stands out
This option falls within the competences of municipal authorities and adjusts, in a very adequate way, the format and the time of generation and consumption of energy, which is the supply of the luminaires that belong to the outdoors public lighting installation
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Energy is one of the main issues discussed worldwide, mainly due to the concerns regarding climate change and the regulatory compliance in terms of greenhouse gases emissions. The continued concerns of the population over energy price increases and climate change issues have led towards a need for alternative and new energy sources. The spread of renewable energy technologies and the need to improve energy efficiency are considered, nowadays, major priorities to be addressed by governments in order to achieve such long-term sustainable objectives.
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