Bir rüzgar enerji santralinin çevresel etkileri
Environmental impacts of a wind farm
Yazar: BUSE BAYINDIR
Danışman: PROF. DR. FATOŞ GERMİRLİ BABUNA
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı / Çevre Bilimleri, Mühendisliği ve Yönetimi Bilim Dalı
Derece: Yüksek Lisans, 2018
Konu: Enerji = Energy ; Mühendislik Bilimleri = Engineering Sciences ; Çevre Mühendisliği = Environmental Engineering
Dizin: Rüzgar santralleri = Wind plants ; Rüzgar türbinleri = Wind turbines ; Yaşam döngüsü = Life cycle ; Yenilenebilir enerji = Renewable energy ; Yenilenebilir kaynak = Renewable resource ; Çevresel etki = Environmental impact ; Çevresel etki değerlendirme = Environmental impact assesment

Özet:
Türkiye'nin elektrik ihtiyacı endüstriyel gelişim ve nüfus artışı ile beraber artmaktadır. Ekonomi ve enerji hedeflerine göre, yenilenebilir enerji kaynaklarının kullanımında önemli bir artış beklenmektedir. Yenilenebilir enerji kaynaklarından biri olan rüzgâr enerjisi, Türkiye'de oldukça yüksek bir potansiyele sahiptir. Bu çalışma, Türkiye'de bulunan bir rüzgâr enerji santralinin çevresel etkilerinin yaşam döngüsü yaklaşımı ile değerlendirmesini amaçlar.
Bu rüzgâr enerji santrali İstanbul-Türkiye'de bulunmaktadır ve 47,5 MW kurulu güce sahiptir. Sistem sınırları, ana parçaların üretiminde kullanılan malzemelerin üretimi, ana parçaların üretimi, montaj, nakliye, işletme ve bakım ve yaşam sonu aşamalarını kapsar.
Ana parçaların üretimi iki bölümden oluşur. Bunlardan biri, kule, elektronik donanım ve kablodan oluşan sabit parçaların üretimidir. Diğer bölüm ise, pervane, sapma sistemi ve naselden oluşan hareketli parçaların üretimidir.
Fonksiyonel birim, üretilen 1 kWh elektriktir. Modelleme için GaBi yazılımı ve çevresel etkilerin sayısallaştırılması için CML 2001 yöntemi kullanılmıştır. Etki kategorileri, Abiyotik Tüketim Potansiyeli (ATP element), Abiyotik Tüketim Potansiyeli (ATP fosil), Asidifikasyon Potansiyeli (AP), Ötrofikasyon Potansiyeli (ÖP), Tatlı Su Canlılarına Ekotoksisite Potansiyeli (TCETP), Küresel Isınma Potansiyeli (KIP), İnsana Toksisite Potansiyeli (İTP), Deniz Canlılarına Ekotoksisite Potansiyeli (DCETP), Ozon Tabakası İncelmesi Potansiyeli (OTİP), Fotokimyasal Ozon Oluşumu Potansiyeli (FOOP), Karasal Ekotoksisite Potansiyeli (KETP) olarak seçilmiştir.
İncelenen rüzgâr enerji santraline ait çevresel etkiler literatürdeki değerler ile uyumludur. ATP (element), ATP (fosil), AP, ÖP, KIP, DCETP, FOOP ve KETP'ne en fazla katkıda bulunan kule üretiminde kullanılan çeliktir. Kabloların üretiminde kullanılan PVC ve bakır tel TCETP'nin ana sebebidir. İTP'ne en yüksek katkıda bulunan malzemeler, yapı temelinde kullanılan beton ve kule üretiminde kullanılan çeliktir. Ana parçaların nakliyesi ve sapma sistemi üretimindeki organik kaplanmış çelik OTİP'nin ana kaynaklarıdır.
Servis süresi 25 yıl olarak planlanmıştır. Servis süresi sonunda, rüzgâr enerji santralinin demonte edileceği kabul edilmiştir. Elektronik donanım metal ve plastik parçalarına ayrılacaktır, her biri toplam ağırlığın yarısı kabul edilmiştir. Metal parçaları geri dönüştürülecek, plastik parçaları düzenli depoya gönderilecektir. Rüzgâr türbininde bulunan diğer metallerin (çelik, alüminyum, bakır) bir kısmı geri dönüştürülecek, diğer kısmı düzenli depoya gönderilecektir. Baz senaryodaki metal geri dönüşüm oranı %90'dır. Beton, plastik, ahşap gibi diğer materyallerin %100'ü, yaşam sonunda düzenli depoya gönderilecektir. İşletme ve bakım sırasında oluşan yağ atığı servis süresi boyunca düzenli depoya gönderilecektir.
Yaşam sonu aşamasında çelik, alüminyum ve bakırın farklı geri dönüşüm oranları ile çevresel etkilerinin değişimi değerlendirilmiştir. Bu geri dönüşüm oranları %80, %70, %60, %50, %20 ve %0'dır. Bu senaryolar için metallerin geri dönüşüm oranı azaldıkça, her erki kategorisindeki çevresel etki değerlerinin arttığı belirlenmiştir.
Ayrıca çevresel etkilerin değişimi, farklı servis süreleri (±5 yıl) kullanılarak da değerlendirilmiştir. Bu değerlendirme sonucu, servis süresinin çevresel etki ile doğru orantılı olduğu, yani servis süresi azaldıkça çevresel etkilerinde azaldığı, servis süresi arttıkça çevresel etkilerin de arttığı görülmüştür.
Son olarak, Almanya'da üretilen pervane, nasel, sapma sistemi, ankraj kafesi ve elektronik donanım gibi ana parçaların Almanya'dan santral sahasına denizyolu ile nakliye edildiği baz senaryodaki koşul yerine, bu parçaların Türkiye'de üretildiği ve üretilen yerden santral sahasına karayolu ile nakliye edildiği alternatif bir senaryo oluşturulmuştur. Bu değişiklik sonucu ATP (element) değeri değişmezken, OTİP değeri artmıştır. Diğer etki kategorilerinde farklı ve küçük oranlarda düşüş meydana gelmiştir.

Abstract:
The electricity demand of Turkey is increasing within the industry and population. Recently, majority of energy generation is supplied by non-renewable sources such as coal (lignite and choke) and natural gas.
Energy production leads carbon dioxide emissions of Turkey. Carbon dioxide emissions of these non-renewable sources are significantly higher than renewable sources such as wind, solar and geothermal. In 2015, in line with United Nations Climate Change Conference, Turkish economy and energy targets are determined that there will be a significant growth in use of renewable energy sources until 2030. Turkey has 48 GW of wind energy potential, which can produce 130 TWh electricity, annually.
This study aims to determine the environmental effects of a Turkish wind farm via life cycle approach. It can be used in comparing and enhancing environmental effects of different energy sources, making regulations with regard to energy generating industry. In addition, this study will be a guide to wind turbine designers and producers, who are willing to have environmentally sustainable production.
The study also has an importance because it is the first study in Turkey, which is about life cycle assessment of an existing wind farm.
Within the scope of study, the system boundary should be defined. System boundary could be determined to the processes, which will be discovered specifically. It divided into four parts, cradle to grave, cradle to gate, gate to gate and gate to grave. The most comprehensive type of system boundary is the one named cradle to grave. Because it covers the extraction of raw materials, manufacturing, construction, operation and maintenance, disassembling and end of use.
After determination of aim and scope, study continues with inventory analysis, which is the most critical stage in a life cycle assessment. Inputs are directly affects the results of life cycle assessment, therefore having actual data is much more reliable than estimations.
A great majority of inputs are obtained the company, which is authorized to operate the wind farm. Information of wind turbine's materials are taken from detailed catalogues of wind turbine manufacturers. When it is needed, scientific articles and reports are referred.
GaBi software is used in modelling and CML 2001 method is used in quantifying the environmental impacts. Impact categories are selected in terms of Abiotic Depletion Potential (ADP elements), Abiotic Depletion Potential (ADP fossil), Acidification Potential (AP), Eutrophication Potential (EP), Freshwater Aquatic Ecotoxicity Potential (FAETP), Global Warming Potential (GWP), Human Toxicity Potential (HTP), Marine Aquatic Ecotoxicity Potential (MAETP), Ozone Depletion Potential (ODP), Photochemical Ozone Creation Potential (POCP), Terrestric Ecotoxicity Potential (TETP).
The studied wind farm is located in Istanbul, Turkey and has 47,5 MW installed capacity. Wind farm has 19 of N100/2500 Nordex wind turbines. Functional unit is selected as 1 kWh electricity produced. System boundary covers the manufacturing of materials in main components, manufacturing of main components, installation, transport, operation and maintenance and end of life stages.
Manufacturing of main components divided into two parts. One is fixed parts manufacturing including tower, electrical equipment and cabling. Other is moving parts manufacturing including rotor, yaw system and nacelle. Rotor comprises of three parts, rotor hub, rotor shaft and three blades. Yaw system is formed from three parts, yaw bearing, drive and brake. Nacelle consists of six parts, main bearing, gearbox, generator, brakes, frame and nacelle cover.
Within fixed parts, tower is manufactured in Aegean Region of Turkey and transported to wind farm by trucks. Cables are manufactured in Central Anatolia Region and transported to wind farm by trucks. Electrical equipment of fixed parts and within moving parts, rotor, yaw system and nacelle are manufactured in Germany and transported to wind farm by sea shipment.
For installation of wind turbines, steel wires and anchor cages are also used along concrete. In this stage, steel wires are manufactured from Aegean Region of Turkey and transported by trucks, while anchor cage are manufactured in Germany and transported by sea shipment. Except of mentioned materials, plastics for cable conduits and wood for timber are also used in installation stage.
In the base scenario, lifetime is planned as 25 years. At the end of service life, wind farm is assumed to be dismantled. Electrical equipment will break into metal and plastic parts, which each of them is half of total weight is assumed. Metal parts will be recycled and plastic parts will be sent to landfill. For the rest of wind turbine components, some parts of metals turbine will be recycled and some parts of them will be disposed. This recycling ratio is 90% in the baseline turbine. The other materials such as concrete, plastics, wood are directed to landfill. Lubricant waste is sent to landfill during the service life.
The environmental impacts of the investigated wind farm are in accordance with the literature values. The main contributor to ADP (element), ADP (fossil), AP, EP, GWP, MAETP, POCP and TETP is steel in tower. PVC in cables is the main source of FAETP. Steel in foundation tower has the highest contribution in HTP. Transport of main components is the main responsible of ODP. The secondary contributor to ADP (fossil), AP, MAETP, POCP and TETP is steel in foundation. Concrete C35/45 is the secondary responsible of EP and GWP. Electronic ballast in electrical equipment has the second highest contribution in ADP (element). For FAETP, HTP and ODP categories, the second contributors are copper wire in cables, steel in tower and organic coated steel in yaw system, respectively. The tertiary contributor to ADP (fossil), AP, POCP is concrete C35/45 in foundation. Steel in foundation is the tertiary responsible of EP and GWP. Aluminium ingot in cables has the third highest contribution in HTP and MAETP. Copper wire in generator is the third responsible of FAETP, while copper wire in cables is the third responsible of TETP. For ADP (element) and ODP, the third
contributors are glass fibres in rotor blades and transport by trucks of materials used in tower manufacturing, respectively.
The environmental impacts are evaluated by changing the recycling ratio of steel, aluminium and copper at the end of life stage. These recycling ratios are 80%, 70%, 60%, 50%, 20% and 0%. For these scenarios, it is determined that when the recycling ratio of metals decreases, values of environmental impact in each category goes up. When these scenarios are considered in detail, ADP (element) and ODP values slightly increases with the lower recycle ratios. ADP (fossil), EP, FAETP and HTP values moderately goes up, when the recycle ratio decreases. However, AP, GWP, MAETP, POCP and TETP values significantly grow up by lower recycle ratios.
The environmental impacts are also evaluated with different life times (±5 years). As a result of this evaluation, it is seen that environmental impacts are proportional to lifetime, which means when lifetime increases, values of environmental impacts also arises or vice versa. With a detail look to these scenarios, ADP (element), ODP, TETP values barely decline, when the life time decreases. However, ADP (fossil), FAETP and POCP values moderately decrease with the shorter life time.
Final scenario is based on transport of main components such as rotor, nacelle, yaw system, anchor cage and electrical equipment. In base scenario, this transport is supplied by shipment, because these components are manufactured in Germany. Built scenario is about changing the manufacturing location. This location is assumed in Aegean Region of Turkey, and transport will be performed by trucks. As a result of this change, it is determined that there is no change in ADP (element). There is an increase in ODP, while the values of other impact categories slightly decrease.