Layang-layang Penangkap Energi Angin

(Energy Neilcy). Ilmuwan di Carnegie Institution dan California State University, Amerika Serikat mengembangkan “layang-layang” yang mampu menangkap potensi energi angin pada ketinggian di atas 9.000 meter untuk membangkitkan listrik. Angin pada ketinggian seperti itu mengandung energi yang cukup untuk memenuhi kebutuhan dunia sampai 100 kali lipat.

Mereka menyatakan New York sebagai lokasi terbaik untuk mengeksploitasi angin di ketinggian tersebut. Para ilmuwan menemukan bahwa kawasan yang paling cocok untuk memperoleh energi sekaligus sebanding dengan pusat populasi berada di Amerika sebelah timur dan Asia Timur. Sayangnya, kekuatan angin yang berfluktuasi masih menjadi tantangan dalam mengeksploitasi energi ini dalam skala besar.

Ken Caldeira dari Department of Global Ecology Carnegie Institution mengatakan, tiupan angin ini jauh lebih kuat dan lebih stabil daripada angin dekat permukaan. Tapi untuk mendapatkan angin ini harus naik sampai beberapa kilometer untuk memperoleh keuntungan besar. Idealnya, harus berada diketinggian sekitar 9 kilometer.

Salah satu skema teknologi yang diajukan untuk memanen energi tersebut adalah layang-layang turbin yang diterbangkan pada ketinggian 9 kilometer. Walaupun namanya layang-layang, bentuk turbin ini sama sekali tidak mirip layang-layang karena hanya berupa tangkai yang di keempat ujungnya memiliki baling-baling. Desain sederhana ini mampu menghasilkan listrik sampai 40 megawatt dan ditransmisikan ke jaringan di permukaan lewat tali penambatnya.

Beberapa kota besar di dunia yang memiliki potensi energi angin high altitude adalah Tokyo, New York, Sao Paulo, Seoul, dan Mexico City.

Sumber :http://www.greenradio.fm/index.php?option=com_content&view=article&id=1147:layang-layang-penangkap-energi-angin&catid=88:wind-power&Itemid=307

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Dunia Usaha Tertarik Energi Angin Laut

(Energy Neilcy). Melalui sebuah iklan di harian sore Belanda NRC Handelsblad 20 perusahaan besar Belanda mendesak pembangunan cepat taman kincir angin di Laut Utara. Sebelumnya Dana Cagar Alam, WWF, bersama PJKA Belanda dan Rabobank mendatangani aksi yang mendukung pembangkit energi tenaga angin. Energi angin laut tampak sangat populer alias hot di kalangan usahawan dan aktivis lingkungan hidup.

Bersama berbagai pihak WWF ingin membangun pembangkit energi sekuat 6000 megawat di laut. Pembangkit energi tersebut dapat meyediakan listrik bagi enam juta rumah tangga dan semua kereta api di Belanda. Angka itu benar, kata Chris Westra, pakar energi angin lepas pantai dari pusat penelitian energi ECN di Petten.

Westra juga menjabat direktur 'We at sea', sebuah think tank soal taman energi angin dalam skala besar di Laut Utara. Dia tahu mengapa perusahaan-perusahaan besar mendadak menyibukkan diri dengan angin laut:

"Karena kami sedikit tegang melihat lajunya semua ini. Baik secara nasional maupun dalam rangka Eropa, pemerintah Belanda berjanji akan membangun sekitar 6000 megawat tahun 2020 dan kalau caranya begini terus, mustahil target itu tercapai. Saya tahu bahwa berbagai kementerian bekerja keras, tapi saya rasa politik harus bergerak lebih cepat lagi. Semua orang harus sadar bahwa kami harus benar-benar serius menanam modal untuk energi angin laut. Dan inilah yang belum dipahami para politisi di Den Haag".

Keuntungan!
Ini bukan berarti bahwa semua perusahaan Belanda tiba-tiba menjadi 'hijau'. Membubuhkan citra ramah lingkungan pada perusahaan membawa keuntungan. Tapi menurut Westra perusahaan-perusahaan besar seperti Ballast Nedam, Siemens, KPN dan penandatangan iklan itu tidak sabar lagi dan ingin membangun taman energi angin laut offshore, karena banyak keuntungannya:

"Investasi di darat menyangkut jutaan. Tapi investasi energi angin di laut menyangkut investasi milyaran. Itulah alasannya. Dan itu pula yag disadari khalayak. Pasarnya luar biasa".

Untuk dapat membangkitkan 6000 megawat engeri angin laut dibutuhkan 1200 kincir angin di Laut Utara dengan kekuatan masing-masing 5 megawat. Menurut Westra tempatnya cukup luas.

Insinyur Cees van den Tak tidak sependapat. Dia bekerja di lembaga penelitian maritim MARIN di Wageningen dan antara lain mengurus keamanan perkapalan sehubungan dengan taman kincir angin offshore. Menurutnya saat ini tidak ada kapasiats untuk 6000 megawat:

"Itu sulit sekali. Mungkin bisa di ujung utara Laut Utara yang tidak padat lalu lintas kapal, tapi itu terllau mahal. Jadi akan terlalu mahal untuk mengalirkan listrik ke pantai dan menuntut subsidi terlalu banyak.

Tabrakan sebuah kapal tangki penuh bahan kimia dengan turbin angin menurut Van den Tak harus dihindari. Kincir angin setinggi 100 meter yang rusak karena ditabrak dan kemudian jatuh di atas kapal dengan muatan lpg, adalah skenario yang sangat mengerikan. Bagi Van den Tak Laut Utara bagian Belanda sudah penuh dan politisi harus mengambil pilihan yang tegas.

Pertahanan, perkapalan, pengerukan pasir laut banyak menyita lahan saat ini dan harus mengalah demi taman kincir angin. Menurutnya kalau pemerintah di Den Haag bertindak tegas, maka 6000 megawat sangat mungkin. Tapi syaratnya hal-hal lain harus disingkirkan.

Angin laut ide bagus?
Masih tanda tanya apakah energi angin laut merupakan opsi yang baik. Karena ini berarti bahwa setiap masalah teknis yang paling kecil sekalipun dibutuhkan kapal; bahwa kincir angin maritim sangat mahal dan transpor energi angin laut ke darat juga membutuhkan banyak dana. Sementara harga energi surya dalam sepuluh tahun mendatang bisa bersaing dengan listrik yang kita dapatkan secara mudah.

Apakah imbauan perusahaan-perusahaan Belanda kepada kabinet akan cepat berhasil masih merupakan tanda tanya. Energi angin Laut Utara menguntungkan, tapi kalau Den Haag tidak secepatnya bersikap jelas, maka perusahaan besar Belanda bisa kehilangan minat menanam modal yang dibutuhkan untuk investasi raksasa tersebut.

Sumber :http://static.rnw.nl/migratie/www.ranesi.nl/arsipaktua/belanda/energi_angin_laut080901-redirected

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Sistem Konversi Energi Angin (SKEA) untuk skala 50 KW

(Energy Neilcy).Lembaga Antariksa dan Penerbangan Nasional (LAPAN) menyiapkan prototipe Sistem Konversi Energi Angin (SKEA) untuk skala 50 KW. Ujicoba ditargetkan awal tahun mendatang di Yogyakarta. Disisi lain, hingga akhir tahun ini, LAPAN hanya menargetkan pemetaan potensi angin di 6 wilayah, atau turun dibanding tahun lalu yang mencapai 8 lokasi wilayah.

“Kami berupaya menambah kapasitas SKEA hingga skala besar. Tahun ini, dibangun prototipe untuk skala 50 KW. Mungkin awal tahun depan sudah diujicobakan di sekitar Yogyakarta,” ujar Drs. Handoko Slamet Riadhi, Kepala Pusat Teknologi Dirgantara Terapan LAPAN di Jakarta

Selain dilakukan uji coba skala 50 KW, tahun depan LAPAN juga berencana membangun desain awal kapasitas 300 KW.

Disisi lain, LAPAN masih mengalami kendala pembiayaan memetakan potensi angin di berbagai wilayah. Hingga akhir tahun ini hanya ditargetkan di 6 wilayah, atau turun dibanding tahun lalu (8 wilayah).

“Butuh kerja keras untuk melaksanakan pemetaan angin. LAPAN tidak bisa sendiri, tapi harus kerja bareng dengan instansi terkait, karena biayanya juga tidak sedikit,” ujar Handoko.

Sumber :www.technologyindonesia.com

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Wind Energy

(Energy Neilcy). Wind Energy – Renewable energy harnesses natural wind power – Effective answer for emission problem towards cleaner, safer and greener environment: Harnessing renewable alternative energy is the ideal way to tackle the energy crisis that looms large over the world. Renewable energy is the energy which is made from resources that Mother Nature replaces. Renewable energy is also called “clean energy” or “green power” because it doesn’t pollute the air or the water. Wind energy is one such renewable energy source that harnesses natural wind power. People try to make many assumptions against wind turbines for generation of wind energy; but the fact remains, wind energy is most suitable form of renewable energy we can have to replace coal fired / nuclear powered / and even oil fired power plants in the near future. In support various points are discussed below:

1. Wind power is a clean, renewable source of energy which produces no greenhouse gas emissions or waste products. Power stations are the largest contributor to carbon emissions, producing tones of CO2 each year. We need to switch to forms of energy that do not produce CO2. Just one modern wind turbine will save over 4,000 tones of CO2 emissions annually.2. Wind energy is generated by blowing air. Wind energy transform in kinetic energy and use as mechanical energy or electricity. The amount of energy produce depends mainly on blowing wind speed; density of air affects the energy produce by wind, which is determined by the humidity, barometric pressure, dryness.

In the case of a wind-electric turbine, the turbine blades are designed to capture the kinetic energy in wind. When the turbine blades capture wind energy and start moving, they spin a shaft that leads from the hub of the rotor to a generator. The generator turns that rotational energy into electricity. At its essence, generating electricity from the wind is all about transferring energy from one medium to another.

The simplest possible wind-energy turbine consists of three crucial parts:

* Rotor blades – The blades are basically the sails of the system; in their simplest form, they act as barriers to the wind (more modern blade designs go beyond the barrier method). When the wind forces the blades to move, it has transferred some of its energy to the rotor.

* Shaft – The wind-turbine shaft is connected to the center of the rotor. When the rotor spins, the shaft spins as well. In this way, the rotor transfers its mechanical, rotational energy to the shaft, which enters an electrical generator on the other end.

* Generator – At its most basic, a generator is a pretty simple device. It uses the properties of electromagnetic induction to produce electrical voltage – a difference in electrical charge. Voltage is essentially electrical pressure – it is the force that moves electricity, or electrical current, from one point to another. A simple generator consists of magnets and a conductor. The conductor is typically a coiled wire. Inside the generator, the shaft connects to an assembly of permanent magnets that surrounds the coil of wire. In electromagnetic induction, if you have a conductor surrounded by magnets, and one of those parts is rotating relative to the other, it induces voltage in the conductor. When the rotor spins the shaft, the shaft spins the assembly of magnets, generating voltage in the coil of wire. That voltage drives electrical current (typically alternating current, or AC power) out through power lines for distribution.

3. Energy of wind power depends upon speed of air when increase in speed of air then increase in generation of energy and when decrease then decrease in energy generation. So locate the wind power plant in windiest areas.

4. The cost of wind energy is determined by initial cost of the wind power plant - any wind power plant that is installed in a windy area generates less expensive electricity than the same unit installed in a less windy area.
5. The average wind farm will pay back the energy used in its manufacture within 3-5 months of operation. This compares favorably with coal or nuclear power stations, which take about six months.

6. A modern wind turbine is designed to operate for more than 20 years and at the end of its working life, the area can be restored at low financial and environmental costs. Wind energy is a form of development which is essentially reversible – in contrast to fossil fuel or nuclear power stations.

7. A modern wind turbine produces electricity 70-85% of the time, but it generates different outputs depending on the wind speed. Over the course of a year, it will typically generate about 30% of the theoretical maximum output. This is known as its load factor. The load factor of conventional power stations is on average 50%. A modern wind turbine will generate enough to meet the electricity demands of more than a thousand homes over the course of a year.

8. All forms of power generation require back up and no energy technology can be relied upon 100%. Variations in the output from wind farms are barely noticeable over and above the normal fluctuation in supply and demand.

9. The cost of generating electricity from wind has fallen dramatically over the past few years. Between 1990 and 2007, world wind energy capacity doubled every three years and with every doubling prices fell by 15%. Wind energy is competitive with new coal and new nuclear capacity, even before any environmental costs of fossil fuel and nuclear generation are taken into account. As gas prices increase and wind power costs fall – both of which are very likely – wind becomes even more competitive, so much so that some time after 2010 wind should challenge gas as the lowest cost power source. Furthermore, the wind is a free and widely available fuel source; therefore once the wind farm is in place, there is no fuel requirement or no waste related costs.

10. In future, we will need a mix of both onshore and offshore wind energy to meet the challenging targets on climate change. At present, onshore wind is more economical than development offshore. However, more offshore wind farms are now under construction. Thus, prices will fall as the industry gains more experience.

11. Wind energy is a benign technology with no associated emissions, harmful pollutants or waste products. In over 25 years and with more than 75,000 machines installed around the world, and there is no report of any body has ever been harmed by the normal operation of wind turbines.

12. The evolution of wind farm technology over the past decade has rendered mechanical noise from turbines almost undetectable with the main sound being the aerodynamic swoosh of the blades passing the tower.

13. We need to act now to find replacement power sources – wind is an abundant resource, and therefore has a vital role to play in the new energy portfolio all over the world.

14. Generation of electrical energy by wind power plant rapidly growing in whole world, In terms of installation and operation world level. Average onshore turbines discussed here is of capacity 1.8 MW. For many on-going projects at present the capacity over 2 MW turbines are being installed. Offshore turbines currently being installed are rated at 3 MW, and it is expected that this will rise to a typical 5 MW per machine by 2010. 15. The benefits of wind energy:
* Wind energy is an ideal renewable energy because:

1. Pollution-free,
2. Does not require fuel
3. Does not produce toxic or radioactive waste.

* Wind energy is quiet and does not present any significant hazard to birds or other wildlife.
* When large arrays of wind turbines are installed on farmland, only about 2% of the land area is required for the wind turbines. The rest is available for farming, livestock, and other uses.
* Ownership of wind turbine generators by individuals and the community allows people to participate directly in the preservation of our environment.16. The Fastest-Growing Energy Source – Wind is the fastest-growing energy source in the world, enjoying an average annual growth rate of 28 percent over the past ten years, compared to less than three percent for fossil fuels. The major drivers of this growth include concerns over climate change and energy security.17. Untapped Potential – Despite monumental growth, wind energy still represents only a minute fraction of total energy consumption worldwide. Increasing this percentage to levels that will contribute to necessary reductions in global greenhouse gas emissions will require significant political support to overcome decades of policies encouraging conventional fossil fuel technologies. If a more level playing field is achieved, wind energy will likely play a major role in future climate change strategies in both national and international arenas.
18. Breakthrough In Small Wind Technology - The main work of wind turbines is to utilize the energy of wind and convert it into electricity; stronger wind is considered good for electricity production. But the speed of wind should not be too strong because it makes turbines spin too fast and in this process it commits suicide! Why is it so? Because turbine blades get ripped off by stronger winds – excessive heat damages the alternator. Turbine tower too can’t remain unaffected by the strong wind. To prevent all this damage a mechanical breaking system furling is generally used. This method prevents wind turbine from spinning too quickly by turning the blades away from the direction of the wind. Furling can be manual or automatic with same goal i.e. turning the turbine blade edges into the wind when the wind is dangerously strong and stormy.
19. Drawbacks - We already know the benefits of wind energy and why we should opt for it. But currently manufacturers are concentrating on the drawbacks of the wind energy and trying to eliminate or minimize those shortcomings. For example turbines are noisy and this sound nuisance can be a problem for the residents of the areas. Wind turbines are unsafe for birds too. Birds can be injured or die if they are caught up in the wings of the turbines. Turbines might annoy you due to horizon pollution i.e. they might meddle with your aesthetic sense.
20. Wind Energy From Ocean Surface – When we talk about wind energy, we don’t specifically mention ocean winds. But global satellite maps from NASA promise a new hope. Nearly a decade of data from NASA’s QuikSCAT satellite gives us hope that we can harness ocean’s wind for energy generation. These maps can help in locating and planning the offshore wind farms for producing electric energy.
21. Next Generation Wind Energy - Right now wind energy is only being harnessed in the windy regions of the earth. Installation of wind energy on individual basis is unpopular because of production and cost inefficiency. Noise pollution and birds getting killed are also not quite attractive side-effects of the windmills. We can’t even imagine of installing windmills on high rise buildings due to their size and cost.
Researchers of university Illinois have thought about all the drawbacks of the windmills and have come up with their own version in the wind turbine technology. Their idea is to have double-helix wind turbine known as ‘aeroturbines’. The design of these aeroturbines is comparatively simple and to eliminate the drawbacks of the existing turbines. Harvesting wind energy from high rise buildings will be possible and production and cost efficiency will be the key factors. The propellers of these aero turbines resemble an electric beater and don’t look like a blade. These aeroturbines will not produce noise pollution and can be installed at the rooftops of high rise buildings. They are safe for birds as well.

22. Cost comparison and Govt. incentives - The cost of utility-scale wind power has come down dramatically in the last two decades due to technological and design advancements in turbine production and installation. The higher the wind speed over time in a given turbine area, the lower the cost of the electricity that turbine produces. Below a comparison of various energy generation costs (average) is shown:Government incentives for both large- and small-scale producers contribute to the economic feasibility of a wind-power system as well.

23. Floating wind turbine launched: Floating wind turbine could lead to offshore wind farms eventually being located many miles offshore, away from areas where they cause disruption. This would benefit military radar operations, the shipping industry, fisheries, bird life and tourism. Floating wind farms could provide an additional source of energy for countries that have run out of space for their onshore wind farms, or where there is not enough wind on land. [Reference: http://news.bbc.co.uk/2/hi/business/8085551.stm ]

As per the recent news, Hywind, the 2.3MW floating offshore wind turbine being developed by Norwegian oil and gas company StatoilHydro, Siemens and Technip has now been installed and moored to the seabed off the coast of Norway. Once cables to the mainland grid have been laid, the wind turbine prototype will undergo a two year pilot which will provide valuable knowledge on how to perfect the technology and hopefully one day enable floating wind turbines to become a financially viable alternative to other energy sources. [Refer: http://www.gizmag.com/hywind-floating-wind-turbine/11961/ ]

Hywind facts in brief:

* Turbine size: 2.3 MW

* Turbine weight: 138 tons

* Turbine height: 65m

* Rotor diameter: 82.4m

* Draft hull: 100m

* Displacement: 5300m3

* Diameter at water line: 6m

* Diameter submerged body: 8.3m

* Water depths: 120-700m

* Mooring: 3 lines
References:

1. http://earthtrends.wri.org/updates/node/277
2. http://englishabc.wordpress.com/2008/03/11/the-leading-wind-energy-trade-fair-2008/
3. http://wings.buffalo.edu/ubgreen/energyforthefuture/technologies/wind.htm
4. http://environmentengineering.blogspot.com/2008/04/wind-energy-renewable-energy-by.html
5. http://saferenvironment.wordpress.com/2008/11/03/wind-energy-renewable-energy-harnesses-natural-wind-power-%E2%80%93-effective-answer-for-emission-problem-towards-cleaner-safer-and-greener-environment/
6. http://science.howstuffworks.com/wind-power.htm/printable

Source :http://saferenvironment.wordpress.com/2008/11/03/wind-energy-renewable-energy-harnesses-natural-wind-power-%E2%80%93-effective-answer-for-emission-problem-towards-cleaner-safer-and-greener-environment/

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Pembangkit Listrik Tenaga Angin

(Energy Neilcy).Angin adalah salah satu bentuk energi yang tersedia di alam, Pembangkit Listrik Tenaga Angin mengkonversikan energi angin menjadi energi listrik dengan menggunakan turbin angin atau kincir angin. Cara kerjanya cukup sederhana, energi angin yang memutar turbin angin, diteruskan untuk memutar rotor pada generator dibagian belakang turbin angin, sehingga akan menghasilkan energi listrik. Energi Listrik ini biasanya akan disimpan kedalam baterai sebelum dapat dimanfaatkan. Secara sederhana sketsa kincir angin adalah sebagai berikut :Indonesia, negara kepulauan yang 2/3 wilayahnya adalah lautan dan mempunyai garis pantai terpanjang di dunia yaitu ± 80.791,42 Km merupakan wilayah potensial untuk pengembangan pembanglit listrik tenaga angin, namun sayang potensi ini nampaknya belum dilirik oleh pemerintah. Sungguh ironis, disaat Indonesia menjadi tuan rumah konfrensi dunia mengenai pemanasan global di Nusa Dua, Bali pada akhir tahun 2007, pemerintah justru akan membangun pembangkit listrik berbahan bakar batubara yang merupakan penyebab nomor 1 pemanasan global.

Syarat – syarat dan kondisi angin yang dapat digunakan untuk menghasilkan energi listrik dapat dilihat pada tabel berikut.Angin kelas 3 adalah batas minimum dan angin kelas 8 adalah batas maksimum energi angin yang dapat dimanfaatkan untuk menghasilkan energi listrik.

Pemanfaatan energi angin merupakan pemanfaatan energi terbarukan yang paling berkembang saat ini. Berdasarkan data dari WWEA (World Wind Energy Association), sampai dengan tahun 2007 perkiraan energi listrik yang dihasilkan oleh turbin angin mencapai 93.85 GigaWatts, menghasilkan lebih dari 1% dari total kelistrikan secara global. Amerika, Spanyol dan China merupakan negara terdepan dalam pemanfaatan energi angin. Diharapkan pada tahun 2010 total kapasitas pembangkit listrik tenaga angin secara glogal mencapai 170 GigaWatt.

Di tengah potensi angin melimpah di kawasan pesisir Indonesia, total kapasitas terpasang dalam sistem konversi energi angin saat ini kurang dari 800 kilowatt. Di seluruh Indonesia, lima unit kincir angin pembangkit berkapasitas masing-masing 80 kilowatt (kW) sudah dibangun. Tahun 2007, tujuh unit dengan kapasitas sama menyusul dibangun di empat lokasi, masing-masing di Pulau Selayar tiga unit, Sulawesi Utara dua unit, dan Nusa Penida, Bali, serta Bangka Belitung, masing-masing satu unit. Mengacu pada kebijakan energi nasional, maka pembangkit listrik tenaga bayu (PLTB) ditargetkan mencapai 250 megawatt (MW) pada tahun 2025.

Sumber :http://renewableenergyindonesia.wordpress.com/2008/03/05/pembangkit-listrik-tenaga-angin/

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Energi Angin

(Neilcy Info).Jenis energi ini akan mengubah tenaga kinetik (0.5 mv^2) dari angin menjadi energi bentuk lain (listrik, windmill, dan pompa). Sehingga untuk pembangkit listrik, formula yang umum digunakan adalah P [W] = 0.5 x rho [kg/m^3]x A [m^2] x (v [m/s])^3 x efisiensi. Sehingga faktor yang sangat berperan dalam pembangkitan energi angin adalah kecepatan, baru disusul luasan turbin (sudu), dan efisiensi. Mari kita bicarakan pertama kali faktor angin.

Kecepatan angin.
Hal yang menarik adalah kecepatan angin. Umumnya (karena alasan kemudahan dan harga), orang mengukur kecepatan udara dengan anemometer. Jika tingkat keakuratan alat tersebut 3%, artinya daya yang dikeluarkan akan berada dalam kisaran +/- 9%.

Hal lain adalah masalah kestabilan kecepatan angin. Sebagaimana diketahui, kecepatan angin akan berfluktuasi terhadap waktu dan tempat. Di Indonesia misalnya kecepatan angin di siang hari bisa lebih kencang dibandingkan malam hari. Di beberapa lokasi bahkan pada malam hari tidak terjadi gerakan udara yang signifikan. Apakah untuk situasi seperti ini, kecepatan rata-rata dapat mewakili (?), padahal di malam hari turbin angin tidak bergerak sama sekali.

Udara yang bergerak dekat dengan permukaan tanah akan mempunyai kecepatan nol dan kemudian meningkat terhadap ketinggian (lihat Gambar di atas). Fenomena ini alamiah terjadi pada aliran dekat permukaan yang tidak bergerak (padahal bumi berputar? khan).

Apa yang menarik?
Pertama, terlalu dekat dengan permukaan tanah, kecepatan angin yang diperoleh akan kecil sehingga daya yang dihasilkan sangat sedikit. Semakin tinggi akan semakin baik. Untuk memperoleh kecepatan angin di kisaran 5-7 m/s umumnya diperlukan ketinggian 5-12 m. Kedua, untuk baling-baling yang besar (katakanlah diameter 20 m), kecepatan angin pada ujung baling-baling bagian atas kira-kira 1,2 kali dari kecepatan angin ujung baling-baling bagian bawah. Artinya, baling-baling pada saat di atas akan terkena gaya dorong yang lebih besar dari pada baling-baling pada saat di bawah. Faktor ini perlu diperhatikan pada saat mendesain kekuatan baling-baling dan tiang (menara) khususnya pada turbin angin yang besar.

Jika kecepatan angin di baling-baling atas dan bawah berbeda secara signifikan, lantas pada kecepatan angin berapa yang pantas dan adil untuk mendesain daya keluaran dari sebuah turbin angin?.

Kecepatan angin juga dipengaruhi oleh kontur dari permukaan. Di daerah perkotaan dengan banyak rumah, apartemen dan perkantoran bertingkat, kecepatan angin akan rendah. Bandingkan dengan kecepatan angin pada daerah lapang. Kepadatan benda (porositas,?) di permukaan bumi akan menyebabkan angin mudah bergerak atau tidak. Faktor porositas ini juga penting untuk diperhatikan manakala mendesain turbin angin.

Fakta angka berikut menarik untuk diperhatikan sebelum membahas lebih dalam lagi tentang energi angin.

1. Wind energy continued its dynamic growth worldwide in the year 2006. 14.900 MW were added in the past year summing up to a global installed capacity of 73.904 MW by the end of December 2006. The added capacity equals a growth rate of 25 %, after 24 % in 2005. The currently installed wind power capacity generates more than 1 % of the global electricity consumption. Based on the accelerated development, WWEA has increased its prediction for 2010 and expects now 160.000 MW to be installed by the end of 2010 [*].
2. Five countries added more than 1000 MW: the United States of America (2.454 MW), Germany (2.194 MW), India (1.840 MW) and Spain (1.587 MW) were able to secure their leading market positions and China (1.145 MW) joint the group of the now top five markets and is now number five in terms of added capacity, showing a market growth of 91 %. Five countries added more than 500 MW and showed excellent growth rates: France (810 MW, 107 % growth), Canada (768 MW, 112 %), Portugal (628 MW, 61 %) and the United Kingdom (610 MW, 45 %). The most dynamic market in 2006, Brazil, faced its long expected take off and added 208 MW which equals a sevenfold increase of installed capacity within one year [*].
3. Turbin dengan daya 550 kW mempunyai tinggi menara 40 m [*].
4. Turbin dengan daya 1,5 MW mempunyai tinggi menara 84 m [*] dan mampu mensuplai listrik untuk 500 rumah.
5. Turbin dengan daya 3,6 MW mempunyai diameter rotor (baling-baling) 111 m [*].
6. Turbin dengan daya 5 MW mempunyai tinggi menara (hub) 154 m dan diameter baling-baling 128 m [*].
7. Kecepatan angin di wilayah Indonesia umumnya di bawah 5,9 meter per detik yang secara ekonomi kurang layak untuk membangun pembangkit listrik [*].
8. Di seluruh Indonesia, lima unit kincir angin pembangkit berkapasitas masing-masing 80 kilowatt (kW) sudah dibangun. Tahun 2007, tujuh unit dengan kapasitas sama menyusul dibangun di empat lokasi, masing-masing di Pulau Selayar tiga unit, Sulawesi Utara dua unit, dan Nusa Penida, Bali, serta Bangka Belitung, masing-masing satu unit [*].
9. Potensi energi angin di Indonesia umumnya berkecepatan lebih dari 5 meter per detik (m/detik). Hasil pemetaan Lembaga Penerbangan dan Antariksa Nasional (Lapan) pada 120 lokasi menunjukkan, beberapa wilayah memiliki kecepatan angin di atas 5 m/detik, masing-masing Nusa Tenggara Timur, Nusa Tenggara Barat, Sulawesi Selatan, dan Pantai Selatan Jawa. Adapun kecepatan angin 4 m/detik hingga 5 m/detik tergolong berskala menengah dengan potensi kapasitas 10-100 kW [*].
Sumber :http://kajian-energi.blogspot.com/2007/08/energi-angin-1.html

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Wind Power

(Energy Neilcy). Main article: Wind power
Vestas V80 wind turbines

Airflows can be used to run wind turbines. Modern wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5–3 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically.[19] Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms.

Since wind speed is not constant, a wind farm's annual energy production is never as much as the sum of the generator nameplate ratings multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favourable sites.[20] [21] For example, a 1 MW turbine with a capacity factor of 35% will only produce an average of 0.35 MW. Over a year, output would be .35x24x365 = 3,066 MWh instead of 24x365 = 8,760 MWh. Online data is available for some locations and the capacity factor can be calculated from the yearly output.[22][23]

Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require large amounts of land to be used for wind turbines, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of ~90% greater than that of land, so offshore resources could contribute substantially more energy.[24] This number could also increase with higher altitude ground-based or airborne wind turbines.[25]

Wind power is renewable and produces no greenhouse gases during operation, such as carbon dioxide and methane.

Source :http://en.wikipedia.org/wiki/Renewable_energy

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