FEASIBILITY STUDY ON OCEAN CURRENTS POWER PLANT I Gusti Bagus Wijaya Kusuma Research Centre for Industry and Energy of University of Udayana Master Program of Mechanical Engineering of University of Udayana Basement Floor, Gedung Program Pasca Sarjana, Kampus Sudirman, Denpasar, 80111, Phone. +62-361-241390, Fax. +62361-241390, Email: [email protected] Abstract The availability of renewable energy in Indonesia is very abundant. Even so, not all renewable energy are viable to be developed, because one of the factors to be considered in choosing the renewable energy business is the annual capacity factor. Annual availability factor of renewable energy in Indonesia for ocean currents is equal to 70%, so when referring to these data, it can be seen that the energy of ocean currents has a quite high on annual availability factor. Based on initial research developed by BPPT, the ideal site for generating ocean currents can also at depth water such as in the Java - Bali strait, Lombok - Bali strait, Lombok - Sumbawa strait, where the electricity is needed in the islands can be used to meet the needs of local community. Nevertheless, in Indonesia is still quite a lot of strait that have not detected its potential for sea currents. Scientifically, the alleged potential of ocean currents in Indonesia holds up to 6 GW of electrical energy. Ceningan Island in Klungkung regency, Bali province, has a fairly strong ocean currents and the potential to generate electric power is about 20 MWe. Ceningan Island is now has been developed as a tourist mainstay of Klungkung regency. With the rapid development of the electricity the issue needs is to develop the tourist area. To better maximize the potential energy that exists in the region is to improving capacity factor and maximize the economic potential, therefore it needs to make a feasibility study in the utilization of marine current energy that can be developed in order to produce high power. Based on the feasibility study, it can be concluded that the ocean currents can be considered as a primary energy costs and economic free right to development in remote areas. Keywords: Feasibility study, potential energy, power generation, ocean currents, flow model INTRODUCTION Indonesian government has set the Presidential Regulation No. 5 of 2006, on New and Renewable Energy with a projected generation of about 25 % in 2025, or about 32.5 GW in 2025. Based on initial research developed, energy from ocean currents can generate approximately 3 GW or 10 % of total renewable energy to be generated in 2025. The government has conducted research to develop sea current power plant on some islands in the strait of East Nusa Tenggara in 2009 and 2011 with a 2 kW output power out of 10 kW that has been planned. In the assessment process of sea currents turbine types, the vertical axis marine current turbine type of Darrieus with three blades is the most suitable for Indonesian waters. This type of turbine construction is simple, easy to manufacture, easy to maintenance, and inexpensive. The test model turbine blades are straight and have profile of elongated shape like an airplane wing foil and aluminum that can be made easily in the casting plant in Surabaya. Another advantage is that the turbine blades can be mounted on two hinges, like doors, that can be driven at an angle of attack (angle of attack) specific. The benefit is to raise the lift (elevator), the bigger the turning moment (torque), and improve the efficiency of the turbine. Model test ocean current turbine has a capacity of 1 kW rotary diameter of 1 meter and 1 meter blade length, has been tested in tensile testing pool. Of several pieces of foil testing different turbine blades , turbine blades rotating ocean currents at very low flow velocities 12:30 m / sec with an average efficiency of turbine without a generator is 42 % . Prototype Sea Power Flow ( PLTAL ) which has been tested using a vertical shaft turbine Darrieus type straight -bladed turbine with a diameter of 2 m and a rotary blade length of 2 m . The result obtained a total efficiency of 35 % with 2 kW turbine generates electricity at current speed 1.4 m / sec. PLTAL generator used is a permanent magnet type generator ( permanent magnetic generator ) with a capacity of 3.5 kW at 250 rpm rotation . To stabilize the electric power fluctuates with the rise and fall of the ocean current velocity output 3 phase AC power to DC. DC current is converted back into a stable AC voltage 220 V and a frequency of 50 Hz through an inverter with a capacity of 2 kW. The study still has a problem of technology, so the results are not optimal. Technology problem lies in construction technology, because the system is where the floating turbines can not operate optimally to drive a generator. In addition, corrosion problems in the system must be resolved so that the life of the tool will increase. In order to produce high system efficiency, the floating mechanism system is replaced with a fixed construction and setting, so that the turbine can spin back - back and expected to increase the exit. Turbines will be equipped with electroplating mechanism to reduce wear and corrosion caused by sea water by combining the turbine blades are stainless steel with system age is 25 years. In order for this research useful, then tested for electrical power generated is equal to 50 kW, so it can be used by a village on the coast . With the improvement of the mechanism of the system, the results of this study are expected to take advantage of renewable energy being very abundant in Indonesia, supporting the national maritime program in which Indonesia as the largest maritime country in the world, can meet the electrical energy in the islands and the acceleration of economic activity in the area of remote islands. MATERIALS AND METHODS According to the background of which has been delivered, the formulation of the problem presented in this study is how to solve the problem of the construction technology power plants ocean currents so that the turbine generator can work optimally. The availability of renewable energy in Indonesia is very abundant. Even so, not all viable renewable energy to be developed , because one of the factors to be considered in choosing the renewable energy business is the annual capacity factor. Annual availability factor of renewable energy in Indonesia respectively - each is 85 % geothermal, biomass 85 % , 70 % of ocean currents, Micro/Mini Hydro of about 50 % , 50 % sea waves, Solar 40 % and Wind 30 %. Based on these data, it can be seen that the energy of ocean currents has an annual availability factor is quite high. Based on initial research, the ideal site for generating ocean currents can also at depth, such as in the Java - Bali, Lombok or Bali - Lombok - Sumbawa, where the electricity is needed in the islands can be used to meet the needs of the local community. Nevertheless, in Indonesia is still quite a lot of the strait that have not detected the potential for sea currents. Scientifically, the alleged potential of ocean currents in Indonesia hold up to 6 GW of electrical energy. Power generation technology in the world with a system of ocean currents have been shown, where the largest turbine that has been made is about 1-1.2 MWe per unit, and has been producing electricity at a competitive price about 9-10 cents / kWh. This price is much lower than the power produced by the diesel engine with a figure of about 20 cents / kwh. Ceningan Island in Klungkung regency, Bali province, has a fairly strong ocean currents and the potential to generate electric power of 20 MWe. Nusa Island Ceningan now been developed as a tourist mainstay in Klungkung regency. With the rapid development of the electricity it needs to be an issue in the development of the tourist area. In addition to tourist facilities, electricity demand is also needed by the local community to drive the water pump, because water for daily needs today is at a depth of 50 meters below ground level. Currently imported drinking water needs of the island of Bali, so the price per liter of its being very expensive. Demand for electricity is also needed for public lighting and for other needs. To better maximize the potential energy that exists in the region, as well as maximizing the economic potential and the capacity factor, the utilization of marine current energy hybrid technology must be developed to generate high power. Ocean currents can be considered as a primary energy costs and economic free appropriate for remote areas. In implementation, it will be analyzed the existing problems and then redesigned for the new model of power generation capacity of 50 kW. Activities will be completed within 3 years. Each party will do according to their expertise. The design of the turbine system, the elements generating machinery, anti-rust and will be implemented by the Research Center of Industry and Energy of University of Udayana. Hydrodynamic model testing is conducted by the Center for Assessment and Research Hydrodynamics. While PT Medco Power Indonesia will design the mechanism of fixing the turbine and generator, in order to generate electrical power in accordance with the purpose of 50 kW. Hydrology study found that speed of ocean currents which are used to design the size of sea water channel. Speed of ocean currents in the Strait Ceningan within 10 months are presented in Table 1 below : Table 1. Data of current speed on Ceningan strait for various depth No. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Month January February March April May June July August September October Average current speed (m/s) Depth 20 m Depth 15 m Depth 10 m 4.5 4 3.5 4 3.5 3 3.5 3 2.5 3 2.5 2 2.5 2 1.5 2 1.5 1 1.5 1 0.5 2 1.5 1 2.5 2 1.5 3 2.5 2 Figure 1. Simulation model of sea current flow Based on the data of speed of ocean currents in the Strait of l Ceningan, then it can be used to make the foundation design for testing ocean currents. Foundation design is done using CFD to get the greatest movement and speed of currents flow. Foundation design ocean currents are presented as in Figure 1. According to CFD simulations on channel sea current water as the driving turbine, then it can be used to design the foundation for testing the sea currents as shown in Figure 2 below. a. Side face of design b. Front face of design Figure 2. Design of channel for current sea flow Several things to be consider in the design of the turbine: 1. Cavitation causes a loss of water turbine, occurs due to burst water vapor in a highpressure flow, become greater if the load becomes smaller, restrictions minimum load about 25% water turbine. 2. Water hammer where the wave that flips that cause mechanical blow pipe which rose rapidly due to upstream water control valve closure and equipped tube dampers the surge tank water hammer. Based on some of the above, the design of the turbine performed as in Figure 3 below. a. Design of turbine b. Slice image of turbine design Figure 3. Design of turbine Design: 1. Head 5 meters 2. Long aqueduct driving 15 m 3. Diameter of 2.5 meters 4. Awakened power 500 kVA 5. Ocean currents flow 0.5 m / s - 4 m / s 6. Interconnection with the transmission of low voltage or can be used directly (off-grid) CFD Simulation and Nastran for turbine design, is presented in Figure 4 below. Figure 4. Simulation plan for turbine design Figure 5. The position of the turbines in the water channel activator RESULTS AND DISCUSSION a. Utilisation Strategy Activities Results of these activities contributed to the community in the form of electricity network that is managed well and can be commercialized to meet the electricity needs of the community on the island of Nusa Ceningan. To be worthwhile, the donations are channeled through operational cooperation between the Provincial Government and the Government of Klungkung regency of Bali, thus ensuring the supply of electricity throughout the 25 years of operation. b. Prospects / Opportunities Product Marketing and Market Acceptance Because electricity is the community needs, the technology of electricity generation from ocean currents is very open to be produced and marketed in Indonesia. Partner support from industry, will accelerate the marketing of these products and can be duplicated quickly to meet the electricity needs of the Indonesian archipelago. Because ocean currents can be considered as primary energy, the electrical energy generated would be very economical and cheap. c. Commercial Feasibility and Business Product or social interventions that can improve the character of the nation Power plant technology with ocean currents is very feasible commercialized, has the advantage of being an Indonesian products that can elevate the image of Indonesia, can be duplicated and expanded in a missal, which will benefit the Indonesian people who are in the islands and untouched by the flow of electricity. With the requirement for electrical energy, then the people in the islands can meet secondary needs or can be used to meet the needs and development of new tourist areas of the Indonesian archipelago, which has stunning scenery. d. Because renewable energy generation system is free of fuel oil, then the expected value of purchase by the government of Indonesia is about Rp. 1500, - per kWh, so this will greatly stimulate the local industry to develop renewable energy in Indonesia. CONCLUSION Based on the simulations that have been done, it could be said that for a minimum speed of 0.5 m/s the flow can produce a maximum velocity of about 4.5 m/s and for ocean current velocity of 4 m/s the maximum velocity obtained of about 36 m/s. Based on the results obtained by the simulation, models of the ocean currents produce the best performance with a slope angle of 30o with a channel length of 15 m where the maximum velocity of the turbine of about 36 m/s with flow pressure of about 201,426 Pa where it is predicted to generate power up to 1,500 kW turbine. REFERENCES Mukhtasor and Firdaus, AM., Technology, Market and Energy Congress, Bali. Gnos, P., 2011. Hammerfest Energy Congress, Bali. 2011. Ocean Energy in Institutional Development. Strøm Tidal Turbine Technology. Indonesia: Policy, World Renewable World Renewable Gilson, P., 2011. Alstoms Tidal In Stream Energy Converter Demonstration Project. World Renewable Energy Congress, Bali. Erwandi, 2011. The Development of Indonesian Vertical Axis Marine Current Turbine for the Tidal Power Generation. World Renewable Energy Congress, Bali. Lubis, S, Hutagaol J. and Yuningsih, A., 2011. Sea Current Patterns In The Straits Of Sunda Lesser As A Possible Location For Renewable Energy Development. World Renewable Energy Congress, Bali.
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