innovative on shore system recovering energy from tidal currents

Abstract An innovative system for the recovering of energy from tidal currents is proposed. The system is composed of a blade submerged in sea waters and connected to a vertical bar which, moving up and down through the tide action, transfers energy to a double effect piston pump. The latter feeds a pressurized reservoir able to provide water flow rate, at a suitable pressure level, to a hydraulic turbine. The basic configuration involves a four-bar linkage connecting the vertical bar and the piston pump. The system can be easily employed in all those sites whose seabed quickly deepens and whose tidal currents are parallel to the coast. The proposed system is a valid alternative to the current tidal energy converters: its big dimensions are necessary to balance the low efficiencies of the overall energy conversion. At any rate, during the working the seabed is not altered, neither is the aquatic fauna damaged

Design and analysis of a new wave energy converter based on a point absorber and a hydraulic system harvesting energy from waves near the shore in calm seas

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hydraulic on shore system recovering energy from sea waves

Abstract The authors propose a new system for recovering energy from sea waves. The system is composed of a large-sized buoy (point absorber), directly connected to a piston pump. The piping, developed underground, allows the water to be moved into a pressurized reservoir, which feeds a hydraulic turbine. The latter discharges the flow in a tank where the hydraulic circuit closes. A sizing methodology developed in the present work, demonstrates the possibility of designing miniaturized components by leaving the possibility of providing an acceptable energy output with low installation costs. A preliminary study demonstrates that a 4.5 m buoy, associated with a small 17 cm diameter Pelton, could be able to recover more than 35,000 kWh/year

Design and Numerical Analysis of a Double Rotor Turbine Prototype Operating in Tidal Currents

Abstract This work shows the results of a study carried out for several years by the Department of Mechanical, Energy and Management Engineering (DIMEG), in collaboration with SintEnergy Srl. The aim was to develop an innovative marine turbine, taking advantagesfrom the tidal currents. The turbine, which is made-up of two concentric contra-rotating rotors, has been designed to operate anchored to the coast without any supporting structures on the seabed. An iterative procedure, based on a zero-dimensional approach, was developed for the estimation of blades dimensions as well as the rotors performances in terms of lift, drag, power coefficient and efficiency. In order to validate the results of the design procedure, numerical simulations based on three-dimensional analysis were also carried out. The three dimensional study was carried out using the commercial code FLUENT, which follows the Reynolds Averaged Navier-Stokes (RANS) approach, in conjunction with the two-equation Realizable k- ɛ turbulence model

Transients Analysis of a Tidal Currents Self-balancing Kinetic Turbine with on Shore Basement

Abstract The aim of increasing the share of renewable energy sources to the total energy production has brought a significant increase of the interest in marine energies over the last years. Within them, tidal currents resources have been gaining ground for their advantages in terms of predictability, nonexistence of extreme flows, high load factor, minimal land occupation and visual impact. The authors, working in this field since many years, have been designing a new turbine able to work in the water like a kite, with no support structures, but easily connected to the coast by a rope. The constructive easiness, together with lower installation costs, are the main machine characteristics. Moreover it is able to overturn itself when the tidal current changes direction. The turbine equilibrium and mainly the transients related to the sink and surface phases, machine overturning, represent a critical aspect of the design. In the present work, starting from a phenomenological analysis, a simulation of the transients has been carried out in Simulink ® environment. The study, related to the center of gravity, has pointed out the importance of the correct floating stabilizer design which helps the turbine to reach the equilibrium conditions even in case of flow instability

Levelized Cost of Energy: A First Evaluation for a Self Balancing Kinetic Turbine

Abstract Since 2009, the team DIMEG Unical and SintEnergy srl have been developing an innovative kinetic turbine able to produce energy form tidal currents. The machine is able to maintain the frontal position to the flow only thanks to its geometry and technical solutions. This turbine doesn't need any concrete structure, nor pylons or floating devices; in terms of energy conversion, it doesn't use any nacelle, gearbox, external generator, but only a little stabilizer, a permanent magnetic generator and a coast anchoring system able to retain the machine during the working operations. A first cost evaluation has been performed in this work, together with an approximate LCOE calculation, in order to compare this device to the other ones in the pre commercialization phase. The project is in an early stage of the development, but quite ready for a prototype realization

Study of a hydraulic system converting energy from sea waves near the coast

This paper proposes a system able to recover energy from sea waves. The system is made up essentially of a floating structure, connected to a piston pump. The pump, constrained to move vertically under the action of the waves, pushes water into a reservoir maintained at constant pressure, from which it flows in a Pelton turbine. A methodology was developed for the preliminary sizing of the proposed system. This methodology takes the height of the waves and the pressure of the reservoir as reference parameters and then provides the main geometric data of the machines. A case study developed in the present work, demonstrates the possibility of designing miniaturized components of the system, able anyway to provide acceptable energy output with contained installation costs

Study of a hydraulic system converting energy from sea waves near the coast

This paper proposes a system able to recover energy from sea waves. The system is made up essentially of a floating structure, connected to a piston pump. The pump, constrained to move vertically under the action of the waves, pushes water into a reservoir maintained at constant pressure, from which it flows in a Pelton turbine. A methodology was developed for the preliminary sizing of the proposed system. This methodology takes the height of the waves and the pressure of the reservoir as reference parameters and then provides the main geometric data of the machines. A case study developed in the present work, demonstrates the possibility of designing miniaturized components of the system, able anyway to provide acceptable energy output with contained installation costs

Design and Numerical Analysis of a Double Rotor Turbine Prototype Operating in Tidal Currents

Abstract This work shows the results of a study carried out for several years by the Department of Mechanical, Energy and Management Engineering (DIMEG), in collaboration with SintEnergy Srl. The aim was to develop an innovative marine turbine, taking advantagesfrom the tidal currents. The turbine, which is made-up of two concentric contra-rotating rotors, has been designed to operate anchored to the coast without any supporting structures on the seabed. An iterative procedure, based on a zero-dimensional approach, was developed for the estimation of blades dimensions as well as the rotors performances in terms of lift, drag, power coefficient and efficiency. In order to validate the results of the design procedure, numerical simulations based on three-dimensional analysis were also carried out. The three dimensional study was carried out using the commercial code FLUENT, which follows the Reynolds Averaged Navier-Stokes (RANS) approach, in conjunction with the two-equation Realizable k- ɛ turbulence model