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
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.
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.
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