Investor Presentaiton
Energies 2019, 12, 3658
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3. Literature on the Issue and State-of-the-Art Technology Related to Ocean Renewable Energy
3.1. Resource Potential
Ocean renewable energy, also referred to as marine renewable energy, is defined as energy
captured by technologies that utilize the seawater's motion or potential properties as the driving
power or harness its heat or chemical potential. The ocean surface waves, tidal range, tidal current,
ocean current, and thermal and salinity gradient are renewable sources of ocean energy that have
different origins. Technologies associated with ocean energy convert these renewable energy sources
into electricity or other desirable forms of energy.
Other renewable sources of energy can be exploited from the ocean environment that is excluded
from the above definition. The production of biofuels from marine biomass, energy harnessing from
submarine vents, and offshore wind are some examples that can be considered as forms of bioenergy,
geothermal, and wind energy, respectively.
The highest level of potential is theoretical potential, which only takes into account the natural
and climatic characteristic limitations. Reducing this potential due to the consideration of the technical
limitations, such as the conversion efficiency and storage of electricity, results in technical potential,
which varies with the development of technologies.
3.1.1. Wave Power
Temporal variations of the wave condition can be estimated by the use of long-term averages in
modeling, applying global databases with reasonably long histories [41]. It can be observed that the
most energetic waves exist in the region between latitudes of 30° and 60° of both hemispheres because
of the extra-tropical storms [41].
Mørk et al. [42] calculated the theoretical potential of wave energy resources for areas with a
wave power larger than 5 kW per meter and a lower latitude than 66.5°. Accordingly, they presented
a total theoretical potential of about 3.37 TW (29,500 TWh/yr or 106.2 EJ/yr). An overall technical
potential of 500 GW (around 16 EJ/yr) was estimated by Sims et al. [43], assuming an efficiency of
40% for wave energy converters installed in offshore regions with a wave power exceeding 30 kW/m.
Krewitt et al. [44] presented a technical potential of 20 EJ/yr. Gunn and Stock-Williams estimated
a global theoretical potential of about 2.11 TW, of which 4.6% was predicted to be extractable by
deploying a specific wave energy converter (WEC) [45]. They considered the area between 30 nautical
miles and the Exclusive Economic Zone (EEZ) for each region. Besides these global studies, some works
have assessed the wave energy resource potential at national and regional levels in China [46,47],
Italy [48], Spain [49], Ireland [50], and the USA [51].
3.1.2. Tidal Power
Tidal ranges can be forecasted accurately. The world's largest tidal ranges occur in the Bay of
Fundy, Canada (17 m), the Severn River Estuary, the United Kingdom (15 m), and the Bay of Monte
Saint Michel, France (13.5 m) [52]. In addition, Argentina, Australia, China, India, Russia, and South
Korea also have large amounts of tidal power.
The global theoretical potential of tidal energy (tidal ranges and currents) is estimated to be in the
range of 500-1000 TWh/yr (1.8-3.6 EJ/yr) [52]. Sims et al. [43] estimated that tidal currents of more
than 100 TWh/yr (0.4 EJ/yr) could be converted into electrical energy if major estuaries with large tidal
fluctuations could be tapped [43].
The Ocean Energy System (OES) reported the worldwide theoretical potential of tidal energy,
including tidal current, to be around 7800 TWh/yr (28.1 EJ/yr) [53]. Some studies of the regional
tidal energy resource potential can be found in Scotland [54], Uruguay [55], Ireland [56], Taiwan [57],
and Iran [58].View entire presentation