Derpris Folmen

Arno Magrufi

4 Type of Wave Power

Point Absorber

Merupakan pelampung pada permukaan yang kaku, baik dalam sistem badan inersia atau damper pada kabel.

Seabased AB Wave Power

Seabased wave energy converter merupakan alat pengkonversi tenaga gelombang laut yang menggunakan generator magnet permanen linear.

Generator ini di desain untuk memanfaatkan pergerakan gelombang, dimana energinya ditransfer dari pelampung melalui kawat

Generator Seabased memiliki tenaga 10-50 kW dengan jumlah generator hampir mencapai 2000 buah.

Proyek ini dikerjakan oleh perusahaan R&D dan Universitas Uppsala di Swedia.

A wave energy converter of the studied type consists to a large part of steel and iron.

The translator body is made of cast iron whereas the buoy, the wire, the stator, the support structure and the casing is mainly made of various types of steel.

The permanent magnets on the translator are made of a neodymium‐iron‐boron alloy (about 24, 75 and 1% respectively).

The stator cables consist of copper wire insulated with cross‐linked polyethylene (PEX).

The wave energy converter is attached to a foundation. The design and material for the foundation is a matter under discussion. For the prototypes made so far, armed concrete foundations have been used

The wave energy conversion research project at Uppsala University is based on a system utilizing the heaving (up‐and‐down) movement of the waves. A buoy floating on the ocean surface is connected by a wire rope to a linear generator on the ocean floor.

The generator consists of a moving part (translator), which is clad with permanent magnets, and a stationary part (stator) with three‐phase cable windings.

The translator moves up and down, following the motions of the buoy, generating a voltage in the cable windings of the stator.

The principle is the same as when a magnet is moved back and forth through a coil, with the translator representing the magnet and the stator representing the coil.

A wave power plant is envisioned to consist of a large number (up to several thousands) of generators placed in arrays on the seafloor.

The studied WPP consists of 1000 generators, placed in arrays of 50 units.

Each array is connected by a sea cable to a low voltage marine substation (LVMS) which in turn is connected to a medium voltage substation (MVMS).

In the LVMS, the irregular power from the generators is converted into a DC voltage and then into a smooth, three‐phase AC voltage.

The voltage is transformed to 12 kV in the LVMS and further to 36 kV in the MVMS.

From the MVMS the power from the generators is transmitted by a sea cable to the electrical grid on shore.

The distance from the WPP to the grid is assumed to be 10 km.

The energy delivered to the grid Egrid from a wave power plant is calculated as follows:

Egrid = Javg × D × Abs × ηgen × Av × ηtrans × N × Life × 8760 [kWh]

Where : Javg = average power flow of the waves [kW/m wavefront] D = buoy diameter [m] Abs = average power absorption rate [%] ηgen = generator efficiency Av = availability factor ηtrans = transmission efficiency N = number of WECs Life = technical service life of the WPP [years]

Case NO is a WPP (as described above) operating in a location with an average wave climate of 20 kW/meter wavefront. This wave climate can be found off the coast of Norway, at least 400 km by ship from Lysekil. The distance used in the study is 650 km. The ship used for transport to the WPP site is assumed to carry 100 WECs at a time and to consuming 30 tons of marine diesel oil per day (24h). The average power absorption rate is assumed to be 12,5%.

Case SE is a WPP operating in a relatively poor wave climate, with an average power flow of 5 kW/meter wavefront. This wave climate is found off the Swedish west coast, near Lysekil. The distance for ship transportation used in the study is 30 km. The ship used for transport to the WPP site is assumed to carry 40 WECs at a time and to consuming 20 tons of marine diesel oil per day (24h). The average power absorption rate is assumed to be 15%.

Varying depth (more than 50 m preferred). The system will have high efficiency because it uses a direct drive

conversion system. The designers of the system say that it will be able to utilize small low

frequency waves and it will be economically viable to use generators as small as 10kW in 1 MW farms.

Feasibility: Environmental impact: Low. The base will have a small impact. Maintenance: Medium. The most critical components are underneath

the water, making it more complicated to service than floating concepts.

Manufacturability: Medium. The base is the most complicated component to install due the under water labor that’s necessary.

About Seabed AB Wave Power Seabased AB develops industrial solutions for sustainable conversion of ocean

wave energy to electricity

One of the great challenges for all wave power technologies is the adaptation of the construction to the extreme forces that occur during storms.

Seabased's wave power technology is based on small units with all parts deployed on the seabed except for a buoy on the surface. Thus the power plant is well safeguarded and can withstand the high forces with a minimum of maintenance.

Seabased's solution results in a robust and very efficient machine with a high capacity factor, which makes it possible to deliver renewable energy at a reasonable cost.

Seabased interconnects the power plants and connects to the grid, as it is on the individual power plants.

Kelebihan :

+ Efisiensi dalam biaya karena alat ini hanya membutuhkan beberapa komponen yang tidak terlalu besar dan mahal dalam pemasangannya.

+ Realibiltas alat ini cukup meyakinkan, karena terbukti mampu menghasilkan energy yang cukup besar dalam pemakaiannya.

+ Alat ini terbukti ramah lingkungan karena tidak adanya penggunaan bahan bakar lagi dalam penggunaannya sehingga tidak mengganggu ekosistem laut yang ada di sekitar daerah pemasangannya.

Kekurangan : Kompleksitas material alat merupakan salah satu

kekurangan pada seabased karena membutuhkan magnet neodymium-iron-boron dalam translator untuk dihubungkan kepada strator.

Gelombang yang kecil serta tidak regular juga merupakan salah satu kekurangan alat ini, dimana saat terjadi fenomena ini, alat tidak akan menghasilkan energy yang maksimal.

Koneksi listrik dalam menghubungkan strator ke generator yang cukup rumit juga merupakan kekurangan, karena hal ini membutuhkan ahli serta perhitungan yang presisi agar tidak menimbulkan kerusakan atau korslet pada dasar laut.

Percobaan alat Seabased

Daftar Pustaka http://www.globeforum.com/en/mainmenu/Archive/I

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