Investor Presentaiton

Energies 2019, 12, 3658 15 of 37 Overtopping devices can be floating or fixed structures. The Wave Dragon [162] and the Seawave Slot-Cone Generator [163] are prototypes that represent overtopping with floating and fixed structures, respectively. In contrast to the other sources, tidal energy can provide predictable and stable power to the electrical network. However, the tidal-current-generated electricity price is not yet competitive with the current wholesale prices of electricity due to the technical challenges associated with building, installing, operating, and maintaining the plant which affect the cost of the produced energy in energetic sub-sea environments [164]. Some important deployments of the horizontal axis tidal turbines are as follows: The Shetland tidal array was the first deployed tidal array. It includes three turbines of 100 kW each. Meygen, which is the largest operational tidal current array with four turbines of 1.5 MW, was developed by ANDRITZ HYDRO Hammerfest and Atlantis Resource Limited. The Sabella D10 tidal turbine has a capacity of 1 MW. The Cape Sharp Tidal project consists of two turbines of 2 MW and was developed by OpenHydro/Naval Energies. The two largest tidal barrages are the 240 MW Rance barrage (1966) in France [165] and the 254 MW Sihwa Lake tidal barrage (2011) in South Korea [166,167]. Other countries, such as China, Russia, and the UK [168], are also focusing on tidal barrage technology. In particular, the former two countries have operated tidal barrage power plants in a mean range of 2.4 m with modern low-head turbines [169], which proves that relatively low tides (lower than 5 m, which is considered necessary for tidal barrages [170]) can also be utilized economically. The extraction of energy from the ocean's thermal gradient is being pursued by some countries including the United States, China, Japan, France, Taiwan, South Korea, India, and the Netherlands. However, two main projects that achieved the prototype phase are the onshore Okinawa 100 kW [171,172] and Hawaii 105 kW OTEC [173] power plants. The former prototype is a hybrid OTEC, developed by Saga University, which uses mixed water/ammonia as "working fluid". It was installed in 2013 in Okinawa, Japan. The latter is a closed-cycle OTEC that was developed by Makai Ocean Engineering. It was installed and connected to the US electrical grid in 2015. Salinity gradient power is still a concept under development [149,150]. The first PRO (pressure retarded osmosis) power plant was developed by Statkraft in 2006. The main project is a 5 kW RED pilot project that was developed by the REDStack and Fujifilm in 2005. They deployed a 50 kW RED pilot project in "Afsluitdijk" (the sea defense site and major causeway) in 2013. 3.3.4. Status of the Projects - Project development phases In general, numerous projects have been implemented in all continents, and some regions present a relatively high TRL compared with others. To address the current status of ocean renewable energy technologies, we integrated the data of 455 projects from five different databases as follows: OES 2019 (Ocean Energy System), EMODnet 2017 (The European Marine Observation and Data Network), UKMED 2019 (UK Marine Energy Database), and OpenEI 2019 (Open Energy Information) provided by the US Department of Energy's Marine and Hydrokinetic Technology Database and PNNL 2019 (Pacific Northwest National Laboratory) [174-178]. Note that, in some cases, mainly related to the wave and current energy, each project may include more than one device unit, forming a farm; however, the numbers that are shown in this section represent the quantity of projects and not the number of the employed technology units. Since each database classifies projects based on its defined categories, unification of the stages of the project development is required. In this work, to unify the classifications of the databases, four different categories were defined based on the "guidelines for project development in the marine energy industry" presented by the EMEC [179]. Accordingly, each marine energy project was divided into seven stages, labelled 0, 1, 2, 3, 4, 5, and 6, associated with the project development strategy, site screening, project feasibility, project design and development,

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