Investor Presentaiton

Energies 2019, 12, 3658 27 of 37 4.2.3. Tidal Power Plant of the Estuary of Bacanga The largest tidal ranges in Brazil are located on the North coast including the coastal areas of Maranhão, Pará, and Amapá. For instance, a tidal energy potential of 22 TWh/year has been estimated for Maranhão state [192]. Some studies have addressed the exploitation of such energy in Brazil [193,194]. As Figure 23a illustrates, the Bacanga basin is 10,219 ha in size, which includes the estuarine body of water and the Bacanga lake. The reservoir capacity is about 40 million cubic meters at an elevation of +4.5 m, corresponding to the spring tide level [192]. As shown in Figure 23b, the dam includes an 800 m embankment rock which is filled with clay material. Additionally, the dam has two sluice gate systems types of radial and stop-log that were installed in 1974 and 1980, respectively. There are three radial sluice gates with widths of approximately 12.5 m. In the case of a fully open gate, a water height level of 4.5 m is registered for each radial gate. This value is about 3 m for the stop-log gates, which are flat and operate vertically, with widths of 2.85 m. (a) (b) RADIAL SLUICE GATES SECTIONS STOP LOG SLUICE GATES SECTION Figure 23. (a) The Bacanga Estuary, and (b) aerial image of the radial and stop-log sluice gates [192]. Considering some restrictions, including a reservoir water level limit of +2.5 m, Neto et al. [192] proposed a new model for the tidal power plant in which the three radial sluice gates were replaced by the modern and appropriate version for automatic operation, which excluded the necessity of using stop-log type gates to control the reservoir maximum limit. Considering the Kaplan turbine with double regulation provided by ANDRITZ HYDRO [195], they estimated an annual energy production of slightly larger than 14 GWh/yr for the power plant. 5. Discussion and Open Question The present cost of ocean renewable energy cannot complete with that of grid-connected renewables. The alternative, nowadays, in addition to the development of more optimized projects, is to look for new markets where electricity generation options are either scarce or expensive, for example the oil and gas industry, aquaculture, defense, and the demands from isolated communities. In the particular case of Brazil, there is a concentration of power generation, mostly from hydroelectric plants, located in the South and Southeast regions. It has been demonstrated that a significant amount of ocean renewable energy featuring an ocean thermal gradient is located in the regions D and C (see Figure 2). In these regions, an annual electricity production of 0.8 TWh per year has been calculated, considering only six OTEC plants with 10 MW installed power, as presented in this paper. Accordingly, considering an annual average of 15 MW, 20 OTEC plants would be sufficient to supply approximately 10% of the total residential electricity consumption of the Northeast region of Brazil, which was estimated to be approximately 27.059 TWh in 2017 [183]. This implies that such renewable energy resources could be harnessed as a supplementary alternative for these regions, especially when there is a power generation drop due to seasonal rain shortage. Additionally, the low seasonal and temporal variability of the ocean renewable resources along the Brazilian coast could provide stable power production throughout the year, with substantial capacity. The supply chain associated with ocean renewable technologies is still incipient worldwide. The increasing prototype deployments may

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