FEASIBILITY STUDY ON OCEAN CURRENTS POWER PLANT I

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.
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