Page 652 - Economia Azul - versão: inglês

Despite decades of efforts to harness the at Lake Sihwa, South Korea, since 2011. direction; point absorbers (OLAYA et al., for example, pneumatic (CAMPOOREALE
energy, its global potential is still very little ex- Advanced marine generation projects, tidal 2014; TODALSHAUG et al., 2016), Figure et al., 2011; CARRELHAS et al., 2019),
plored (REN21, 2018). Over the last decade, current power plants ranging from 10 kW to 2e, which have small dimensions in relation hydraulic (FALCÃO, 2008; ZHANG et al.),
ocean energy sources have grown significant- 1 MW, have been deployed primarily in the to the predominant wavelength and are mechanical actuation direct (ALBERT et al.,
ly. Since 2010, many devices have been de- UK, Canada, Australia, and China. However, generally axisymmetric in relation to their 2017; YIN, et al., 2017) and direct elec-
ployed around the world to capture energy these demonstration projects remain costly vertical axis; and submerged oscillating bod- tric drive (MUELLER, 2002; LI et al., 2016).
from waves, currents and tidal ranges, and and have not yet achieved the economies of ies (SERGIIENKO et al., 2016) (Figure 2f), A detailed description of these systems
thermal and salinity gradients. Globally, this scale necessary for significant cost reductions which are large, submerged buoys. Overtop- can be found in OZKOP et al. (2017) and
growth has more than doubled, from 244 (IEA, 2021). Ocean renewable energy tech- ping uses the phenomenon of water flow- WANG et al. (2018).
MW in 2009 to 526.8 MW in 2021 (IRENA, nologies are still in the conceptual, R&D, or ing over the top of a barrier to supply water 2.2 Conversion of tidal energy
2021). However, more than 90% of this op- demonstration prototype stages. In the case to a reservoir, in which water flows through
erational capacity is represented by two tidal of waves and tidal currents, based on current low-head turbines coupled to a generator Tidal dams use the variation in tidal am-
dams, which have been operating commer- developments, global commercial application to produce electricity (KOFOED, 2006; LIU, plitudes during low (headwater) and high
cially, at La Rance, France, since 1966, and is expected in the medium term. 2017), Figure 2g. Others, describing con- (full) conditions to drive turbines similar
cepts different from the above categories, to those used in hydroelectric dams. The
2. Concepts and technologies for example, the wave carpet (ALAM, 2012) greater variation in tidal amplitude results
and the rotating mass (DURAND et al., in greater energy extraction by the plant.
2.1 Wave power converters
2007; ZHAN et al., 2017), which uses the The shape of the structure is similar to
Currently, there are a large number of oscillating body, and overtopping. The Os- movement of a hull to accelerate and keep hydroelectric dams, being generally built
concepts and patents on the use of wave cillating Water Column (OWC) compress- the revolutions of a rotating mass within it. in the estuary of rivers or bays to store wa-
energy. The wave energy conversion pro- es and decompresses the air in a chamber, There are different types of PTO sys- ter at high tide. The difference in heights
cess can be divided into three main steps: from the elevation of the wave, to drive a tems adopted for wave energy converters, of the water surfaces on the inner and
the primary conversion step, the second- turbine coupled to a generator, producing
ary conversion step, and the tertiary con- electricity. Depending on the installation Figure 2 - Categories of wave energy converters
version step (E.R., 2019). In the primary location, OWC devices can be installed on
conversion stage, the wave converter cap- the coast (HEATH, 2012; FERNANDES et
tures the kinetic energy of waves through al., 2018). Figure 2a, or floating, Figure 2b
interactions between the converter and (BULL et al., 2016; FALCÃO et al., 2016).
the wave, for example, float oscillation, air Oscillating bodies use wave motion to ex-
flow or water flow. The secondary stage cite two bodies of a converter, so that the
converts the energy of body movement relative motion between the bodies, with
into electricity through the electrical gen- the aid of a generator, produces electric-
erator (power take-off – PTO). In the tertia- ity. According to dimension and orienta-
ry stage, the characteristics of the energy tion, these systems can also be classified as
produced are adapted to the requirements terminators (DIAS et al. 2017), Figure 2c,
of the network with a power electronic positioned with large horizontal extensions
interface. Based on the working princi- perpendicular to the wave propagation di-
ples of the wave converter’s primary and rection; attenuators (YEMM, 2012; ZHENG,
secondary conversion stages, the classifi- 2017) (Figure 2d), with a large horizontal
cation includes oscillating water column, extension parallel to the wave propagation Source: SHADMAN et al., 2019

650 BLUE ECONOMY Renewable Energy in the Ocean 651