Pitch

The SEWAT project aims to produce sustainable energy, in large quantities and at high power, with relatively small static and modular plants, exploiting the energy possessed by the waves of the sea, even if of small size. Our system is modular, scalable and replicable ; it is conceptually extremely banal and uses technologies very simple in use in other fields, but is able to produce a lot of energy without waste, waste water , CO2, risks and implications harmful to the environment and the community. The possibility of pollution is non-existent. It is occupied a marginal waterfront that cannot be used for other purposes, it does not take away space for other activities and does not create substantial impediments to navigation. The plants can be located outside the breakwaters or, themselves, can perform the function of breakwaters to create ports or to protect the coast. The secondary objective, in fact, linked to the particular geometry of the system, is to protect the coast from erosion and to guarantee an effective restoration of the beaches. It uses common technology and commonly used materials that do not present supply problems. Electricity, characterized by great variability, can be fed into the grid only after stabilization. The portion of energy produced in excess of consumption can be used to produce green hydrogen which would constitute the energy accumulator pending its use in periods of reduced productivity. An estimate of the power involved is difficult, because the exploitation of this energy source has not a historical past and because the proposed installation is completely new. In the technical literature there are not developed theories or reliable data. A module about 50 meters long and 6 meters wide should produce an useful power (electricity) of about 180 kW with a sea force 3. The power becomes equal to 2500 kW during periods of sea force 6.

Summary

The way of exploiting wave energy with the SEWAT device is very simple but very effective and is inspired by the observation of the natural scenery offered by the breaking waves

When the wave breaks on the rocks, the water rises on the cliff and then falls uncontrollably.

So in nature there is the dissipation of wave energy which often involves the erosion of the coast.

With the proposed SEWAT device we want to control the fall of the water of the breaking waves with the aim of obtaining energy.

The proposed device is a collector that collects the energy that waves have received from the wind over an absorbent surface area of hundreds of square miles. Consequently, the energy density (understood as the energy obtainable per unit of occupied surface) is very high and allows to obtain high powers.

It should be noted that energy is not subtracted from other natural systems, because the captured energy would still be naturally dissipated.

The SEWAT project  is currently in an experimental phase. Qualitative tests were carried out using a model in order to validate the concept (Technology Readiness Level – TRL3 experimental proof of concept). At present we are building an experimental prototype to be tested at sea in real conditions (TRL 7 system prototype demonstration in operational environment). It will be located in the sea next to a breakwater barrier in the Municipality of  Torchiarolo (Brindisi).

The purpose of experimenting with the prototype is to test the productivity of the system and gain further knowledge for the development of the project

Idea

The very simple but ingenious idea concerns the production of large quantities of renewable  energy, using the energy of small waves in a sustainable way.  No risk, no dangerous implications and no CO2 production. The goal is to exploit energy from a source that has so far been considered marginal. The system consists of modular concrete tanks, placed in the sea, partly submerged, placed on the side of sea wall and breakwaters barrier exposed to the waves or in the distance, parallel to the coast, at a certain distance to protect the coast itself.

The function of the tank wall exposed to the action of the waves is to capture the waves. It is equipped to allow waves to enter and to prevent them from exiting.

The capturing wall of the tank is made of steel panels with horizontal openings through which water enters in the tank. Each passage is closed by mobile floodgate. By the action of the waves the floodgates open automatically, allowing the ingress of the water into the tank.

The water enters but it can not go out because of the automatic closure of the floodgates, caused by the hydrodynamic effect, so it accumulates in the tank reaching a level which depends on the height of the waves. The floodgates act as «check valves».

Then, the water in the tank collects, up to a height greater than that of the «calm sea» which is on the sheltered side of the tank. The water collected in the tank therefore has potential energy, which can be exploited by  racking the water into the calm sea through micro hydraulic turbines operating thanks to the flow of water.

Each micro turbine  drives an electric generator to produce electricity. The number of micro turbines operating at the same time depends on the state of the sea because, to optimize the system and have a stable operation, it is necessary to have transferred almost all the water previously accumulated in the tank when the next wave arrives.

Electricity, characterized by great variability, can be fed into the grid only after stabilization. The portion of energy produced in excess of consumption can be used to produce green hydrogen which would constitute the energy accumulator pending its use in periods of reduced productivity.

The modularity of the system allows the construction of extended systems formed by a succession of juxtaposed modules.

Each module, just built, goes immediately into production, helping to finance the subsequent modules. For this reason, the initial investment is relatively limited.

Impact

STRENGTHS:

the production of energy takes place in a truly sustainable way with a positive impact on the environment because it does not imply any negative influence on the environment at a global level, while at a local level it involves an improvement of the ecosystem.

The strengths can be listed as follows:

1. low operating costs reduced only to maintenance costs;
2. no environmental impact during construction, operation and decommissioning;
3. no risk and dangerous implications;
4. protection of sea walls and coastlines due to the tanks;
5. construction of extended plants using simple modules;
6. use of simple technology already tested and used in other fields;
7. a marginal water-front is occupied which cannot be used for other uses, so no space is taken away for other activities;
8. the supply of raw materials is limited to the plant construction phase and, to a limited extent, to the maintenance phases. In fact, during the production phase, the energy obtained comes entirely from the wave motion, as the system is self-powered. The materials needed for the construction of the plant are common, (essentially concrete, steel, etc …) that are easy to find, frequently used in daily practice, non-polluting and recyclable. The quantities of the materials used are not such as to alter the market for them.
9. neither chlorine nor any other antifouling and antiscalant substance or method is used; the «marine fouling» is removed from the functional parts (absorbing panels, gates, turbines, etc.) by drying in the air;
10. there is no production of CO2, slag, residues or wastewater to be disposed of or stored, neither in the construction phase of the plants, nor in the management phase, nor in the decommissioning phase at the end of the production cycle which, moreover, it is estimated to be extremely long, certainly greater than 50 years;
11. the sand that is deposited in the tank can be used for nourishment of the coasts, while the algae and encrustations, removed during maintenance, can be used for the production of biofuels;
12. if the plant is built next to sea walls or breakwaters, the sea

currents and the landscape are not altered, so its construction does not have a visual impact;

13. if the plant is built in an isolated position, it can replace the function of coastal protection performed by coastal defenses or the function performed by breakwaters for the construction of ports;
14. in operation, large quantities of water coming from the open sea, clean and ventilated by the wave motion, are poured into the calm sea, sheltered by the tank itself. This process contributes to the oxygenation and turnover of  water present in ports or closed basins that inevitably are formed with the construction of coastal defenses or breakwaters. In this way, the optimal conditions are created for the development of quality fish farming because, although located in stretches of sea sheltered from the waves, it has the typical offshore characteristics;
15. inside the tank, the waste present in the sea accumulates, with the possibility of being able to remove and dispose of it;
16. during periods of calm sea and therefore not productive, during which maintenance operations will take place, it is possible to capture in a non-traumatic way the protected fish species that have remained imprisoned in the tank, in order to analyze, study and catalog them before their release at sea;
17. the EROEI (Energy Returned On Energy Invested) index is extremely high, (the ratio between usable energy and the energy costs to obtain it) certainly higher than most energy sources currently exploitable;
18. The wave energy, if not exploited, is naturally dissipated, producing erosions and damage to the coastal system. The proposed system, on the other hand, captures this energy without taking it away from other ecosystems and without creating imbalances and environmental alterations.

DANGEROUSNESS OF THE PROCESSES:

a simple technology is used that does not involve the use of toxic or harmful substances, already tested and in use in other areas of technology, totally free of dangers, risks and implications for the community.

No hydrocarbons or other substances are used that can, even incidentally, produce environmental pollution.

TIME FOR COMMISSIONING:

the time for commissioning is relatively limited thanks to the modular construction and non-invasive industrialized prefabrication. It is possible, in fact, to create very extensive systems as a succession of prefabricated modules, with the advantage that each module, whose construction requires relatively modest time and resources, immediately goes into production as soon as it is completed.

POINTS OF WEAKNESS:

The production of electricity is highly variable both in the short and in the long term, being linked to the conditions of the wave motion.

This negative aspect can be overcome by providing for stabilization of energy  and the production of hydrogen.

If the plant is in an isolated location, it will be visible from the mainland.

This impact will be less and less noticeable the greater the distance from shore. In this case it may be an opportunity to develop a whole series of activities ranging from pleasure to tourism and fish farming, etc. .. which can take place at a distance from the coast but sheltered or based on the tank itself. It is obvious that this latter arrangement of the system involves, albeit in minimal terms, an interaction with the landscape, but, in the long term, it will certainly have less impact than non-installation and therefore the renunciation of capturing sustainable energy necessary for mankind.

About

the company GECO – Global Engineering Constructions – s.r.l. based in Brindisi, it owns the SEWAT project.  ( patent n. BR2010A00004 extension PCT / IB2011 / 053091)           https://gecobr.wixsite.com/sewat     gecobr@libero.it

The team that takes care of the project management is composed of:

Giulio Teodoro Maellaro – engineer

Cosimo Maellaro -engineer

Felice Frascino – engineer

Antonio Frascino industrial expert