In a context of increased fossil fuel scarcity and
with environmental questions being taken more into consideration, ocean
energies are certain of a future in the European and worldwide energy
scene. These energies have to be considered in the plural form because
the sector covers the energy exploitation of all energy flows
specifically supplied by the seas and oceans: waves, tidal currents,
ocean currents, osmotic pressure (the differential in salinity of marine
currents that can create a flow and which, in turn, can be used to
produce electricity) and thermal gradients.
At present, most efforts in both R&D and experimental
implementation are concentrated on tidal currents and wave power.There
is an amazing diversity in converters capable of transforming these
flows into electricity, and more than thirty can be counted. The most
effective solutions should emerge as the sector matures.
90% of today’s worldwide ocean energy production is
represented by a single site: the La Rance Tidal Power Plant (240 MW)
that was commissioned in 1966. This type of
installation has remained unique in the world and has only been
reproduced at much smaller capacities in Canada (20 MW), China (5 MW)
and Russia (0.4 MW). This type of project was abandoned for many years
because of very high initial investment costs as well as the strong
local impact that results from it. However, the present economic
situation has encouraged South Korea to build a 260 MW dam closing off
Sihwa Lake, which is set to be commissioned in 2009. Lighter new
techniques, like hydro turbines, are being developed today to harness
ocean currents. The leader in this field, the British company, Marine
Current Turbine (MCT), should install 1.2MW in Northern Ireland
following its 300 kW pilot project in Bristol Bay.
Among the different converters capable of exploiting
wave power, the most advanced is unquestionably the Pelamis Wave Energy
Converter, a kind of “undulating sea serpent” developed by Ocean Power
Delivery. This technology is the object of a commercial contract for
installation of a farm in Portugal. At present, three machines, with a
total capacity of 2.25 MW, are in installation phase, and should be
joined by 27 others in the years to come. Another 5 MW project is being
studied for England this time.
It should be noted that this sector is attracting
more and more interest. In this way, the Coordination Action for Ocean
Energy Project (CA-OE), which groups together 41 members, was created at
the end of 2005, with the support of the European Commission, the
European Ocean Energy Association (EUOEA). In terms of the large
industrial groups, Voigth Siemens Hydro has integrated the English
company, Wavegen, which has been exploiting a rival to the Pelamis
converter since 2000, while the English subsidiary of EDF has taken a
25% share in MTC’s SeaGen Project. For its part, the Total oil company
has invested 10% of a pilot project located in Spain, using the
PowerBuoy, manufactured by the American company OPT.
Ocean energies must face up to two challenges. First
of all, progress has to be made in finalising and perfecting
technologies and pilot projects have to be validated: the density of
water, which is 800 times greater than that of air, makes the
installation and maintenance of sites that are constantly subjected to
extreme forces difficult. And, above all, costs must be brought under
control. The French Ministry of Industry estimates investments between
1,000 and 3,000
