Jul 21 2011


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The logistics of a wind energy project are complex from start to finish. To better describe the process, it has been broken down into five stages: planning, manufacturing, construction, operation, and decomissioning.


Planning is one of the most important stages of developing a wind energy project. Spatial planning and site selection are based on many factors; the main factor is picking an ideal location that supports grid compliance, avoids possible obstacles and environmental impacts, and is cost efficient (“Siting”). Suitable locations for offshore wind include those situated before the continental shelf, with a highly rated wind class and stable bottom (Musial). Obstacles that may prevent the development of an area include: shipping lanes, pipelines, commercial and recreational fishing areas, and areas of constant migration of birds and marine animals. It is vital to pick a location that does not harm marine ecosystems to a point of no possible recovery (Mineral Management Service). When planning an offshore wind energy project, policies and permitting are a major aspect. In the United States, permitting through Mineral Management Service takes between 7-9 years. Usually, state agency permitting is also required (Gibbs). While possible locations are analyzed and eventually selected, companies around the world are manufacturing wind turbines.


North Carolina Offshore Wind Map---http://www.windpoweringamerica.gov/images/windmaps/nc_90m_offshore.jpg


Manufacturing wind turbines is an extensive process that is only the second step in a wind energy project. The number one producer of wind turbines is a company named Vestas. Based out of Denmark, they hold 14.8% of the annual market share, based off of 2010 (Acher). Vestas manufactures 100% of the transformers, gearboxes, generators, and control systems necessary for turbine functioning “in-house”. 98% of blades and 25% of towers are also manufactured “in-house” making Vestas one of the most efficient turbine manufacturers. Manufacturing “in-house” entails building each component in its own specialized factory; the components can be built in Vestas’ many factories around the world (“Manufacturing”). The first US company to make the “Top Ten List” is General Electric. Rated fourth in the world, GE holds 9.6% of the annual market share (Acher). GE’s 4.1-113 turbine was created solely for offshore use. This turbine has a capacity of 4.1MW when operating at maximum potential and is rated for 14 m/s wind speed. This turbine is comparable to many of the other top producers’ offshore turbines (“Wind Turbines”). Surprisingly, there are many turbine manufacturers in the US. Over 70 companies manufacture components in Great Lakes region. This proves that producing wind turbines in the US could be cost efficient and support the local economy instead of importing turbines from European Countries or China (Tegen). Once the manufacturing phase is complete, the components of the turbine are transported and constructed at the wind energy project site.


GE's 4.1-113 Offshore Turbine---http://www.ge-energy.com/content/multimedia/_files/photos/41d.jpg


To construct an entire wind farm in Europe takes roughly six months; however, experts estimate that a project would take approximately two years to complete in America (Mineral Management Service).  The construction of an individual turbine is modular in nature. Each individual element is manufactured in a separate location, brought to a staging area near the wind energy project, then final assembly takes place on location, utilizing barges and cranes. The very first step in the process is to lay out all of the transmission lines that the towers will use to transmit their power to land-based substations. The first step in actual construction is to drive a foundation into the sea bed using a hydraulic or pneumatic press. Most commonly that foundation is a monopole design (Barrow Offshore Wind). The foundation is one of the most expensive parts of an entire project, often accounting for up to 35% of total production costs (Byrne). The foundation has to be extremely strong as it must withstand forces from all sides. The downward force from the turbine itself is fairly low, but the side-to-side force generated by the waves is very strong. While the foundation is being built, the rest of the turbine is coming together at a factory. The tower, which physically supports the nacelle and blades, is welded together in sections and made of steel (Cape Wind Associates). Next, the nacelle is lifted on top of the tower. The nacelle houses all of the gears used to turn the generator (Ancona). The gears are typically made of specialized steel to withstand the stress placed on them (Cape Wind Associates). Lastly, the rotor blades are lifted into place. Typically rotors are made of lightweight materials such as fiberglass (Cape Wind Associates), carbon fiber, or glass reinforced plastic (Ancona). When they are finished, the turbines are ready to begin producing power for the community they serve.



The operational phase of a wind turbine’s life requires constant monitoring. Parameters such as wind speed, direction, temperature, and efficiency are constantly measured by the energy companies and the companies that installed the turbines (“Operation and Maintenance”). Turbines also face many dangers while they are operating. Salt water is an extremely hostile environment for any technology to exist in (Musial).  Hurricanes and Nor’easter storms pose a great threat to the coasts of North Carolina, and could damage any turbines placed offshore. Turbines then, must be equipped with a way of protecting themselves in the event of a storm. Through a mechanism called feathering, turbines will change the angle of their blades in order to create the least amount of friction with the wind as possible (Siemens). The turbines will continue to produce power as long as they are well-maintained.




After a turbine has lived out its productive life, it must be decommissioned. Decommissioning is basically the same process as construction, only in reverse (Barrow Offshore Wind). The time frame for decommissioning is also similar to that of construction, taking approximately six months. Currently, offshore wind turbines from most major producers have predicted life spans of between 20 and 25 years. Also, going into the future, it may become possible to build new turbines on the foundations that already exist from old ones. This means that the physical footprint of the foundations could long outlast individual turbines (Mineral Management Service).

A wind turbine foundation -- http://www.eurotrib.com/story/2006/10/26/155548/15


“A wind turbine can be compared to a fan operating in reverse: rather than using
electricity to produce wind, the turbine uses the wind to make electricity” (Department of Energy).

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