The analytical and experimental study on the establishment of a tidal power plant in South Africa

The majority of South Africa’s electricity is generated from fossil-fuel plants that use mainly coal. In these power plants, the combustion of these fossil fuels liberates greenhouse gasses into the atmosphere that contribute to climate change. This problem coupled with the rapid depletion of fossil fuels has necessitated the need to explore the alternative form of energy such as renewable energy. Tidal energy is a form of ocean energy that can be considered as an alternative energy resource or renewable energy source. This form of energy has not been explored in South Africa, the only country in the world that is bounded by two oceans; the Indian and the Atlantic. Tidal energy can be harnessed from the movements of tides to generate electrical power. This study considered the possibility of harnessing tidal energy as the alternative energy source for power generation which can be used to mitigate the challenges associated with the energy crisis currently being experienced in the country. For this study, an extensive literature review was carried out to understand the tidal phenomenon, the concept of energy conversion from tides, the different techniques or technologies that can be used to generated power from tides. There are two main technologies used for converting tidal energy to electrical energy and these are the tidal barrage and the tidal streams. Based on the inferences drawn from the literature reviews concerning the tides experienced around the South Africa coastal region, it was identified that the tidal stream technique is applicable. Harmonic analysis of the tidal resource for four identified sites was conducted, from these analyses, Esikhawini was selected as an optimum site. Tidal streams extract the kinetic energy of tides and the mode of operation of tidal stream plants is determined by the type of tidal turbine employed. Several turbine designs were reviewed, a helical cross-flow turbine was selected due to its self-starting capability and its ability to operate in reverse stream flows. For this helical turbine, an analytical model using the blade element momentum theory (BEMT) was developed and was implemented on MATLAB environment. For the experimentation, a prototype was developed and tested in a laboratory concrete flume in the department of Civil Engineering at the University of KwaZulu-Natal. Based on the experimental results, an analysis of the unit turbine was done which was used to propose a conceptualized tidal power plant. Hence, the proposed tidal power plant was used to justify the reason for embarking on this study which is to ascertain the possibility of establishing a tidal power plant in South Africa.

MICROBIOLOGICAL ANALYSIS OF THE SAMPLES OF MATERIALS LOCATED IN THE COASTAL ZONE OF THE BARENTS SEA

The composition of the microbial community isolated from the surface of samples of structural materials located in the area of the Kislogubskaya tidal power plant in the Barents Sea was determined. Groups of potentially corrosion-active microorganisms were identified using selective culture media. The Pseudomonas fluorescens strain, belonging to the group of iron-oxidizing bacteria, characterized by a chemoorganotrophic type of nutrition was isolated. The morphological, physiological, biochemical and cultural characteristics of the strain and the analysis of the 16S rRNA gene sequences were determined.

HYDRAULIC INVESTIGATIONS FOR THE ENVIRONMENTAL IMPACTS DUE TO TIDAL ENERGY DEVELOPMENT

New ocean renewable energy has been developing around the world for a goal of reducing greenhouse gas emission. Tidal energy is more powerful and it has potential for future electricity generation among several ocean renewable energies even though not yet widely used. Also tides are more predictable than wind energy and solar energy. SIHWA Lake Tidal Power Plant in South Korea is the largest tidal power installation in the world, with the total power output capacity of 254MW. The project was opened in 2012 and a 12.5km long seawall constructed in 1994 for flood mitigation and agricultural purpose. Power is generated on tidal inflows into the 30km² basin with the help of ten 25.4MW submerged bulb turbines. Eight culvert type sluice gates are used for the water outflow from the barrage. The amount of discharge flow in total ten of turbines is 3,000 m3/sec, and discharge flow in eight of water gate is 8,500 m3/sec. At the time when SIHWA Lake Tidal Power Plant was designed for construction, its flow velocity was predicted as less than 2m/sec in front of water gate. Accordingly, discharge flow should have no significant impact on navigation channels and several berth facilities. It also should not affect on ship navigation. However, within a year after the first run on April 2012, more than 2.5m/sec of flow velocity was generated and it damaged on navigation channels and berth facilities. Increased flow velocity at SIHWA sea area is directly impacting on ship navigation. In severe case, it will cause human and physical damages. In order to prevent these damages, it is necessary to find the causes and countermeasures of increased flow velocity for reduction in flow velocity of discharge.