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Offshore wind power refers to the construction of wind farms in bodies of water to generate electricity from wind. Unlike the term typical usage of the term "offshore" in the marine industry, offshore wind power includes inshore areas such as lakes, fjords and sheltered coastal areas, utilizing traditional fixed-bottom wind turbine technologies, as well as deep-water areas utilizing floating wind turbines.

In 2008, offshore wind power contributed 0.8 GW of the total 28 GW of wind power capacity constructed that year.

By October 2009, 26 offshore wind farms had been contructed in Europe with an average rated capacity of 76 MW.

Economics and benefits
Most entities and individuals active in offshore wind power believe that prices of electricity will grow significantly from 2009, as global efforts to reduce Carbon emissions come into effect. Based on this, offshore wind power is expected to have independent viability in the mid-to-long term.

In 2009, offshore wind power depends on public schemes for its viability. Many governments, especially in Europe, have put such schemes into place in order to ensure increase the construction of Offshore wind farms. Typical schemes include Feed-in Tariffs, Renewables Obligation such as the UK's Renewables Obligations and direct public subsidies.

The rationale for the support schemes has several aspects, of which some or all may be relevant in each country or region that set them up:
 * Current electricity prices do not include the costs of the carbon footpring of traditional sources of electricity (externalities)
 * Supporting the offshore wind sector in its infancy is an investment into technologies, skills and organizations that will give an economic return in the future
 * In the EU specifically, each country is working toward its goal as part of the commitment to increase the share of renewables in energy use by 20% by 2020
 * Offshore wind can be built close to big consumption centra, which are typically located in coastal areas
 * Offshore wind, especially if developed >20–30 km from land, tends to meet with much less public resistance than alternative means of solving electricity shortages (such as onshore wind, new transmission power lines or "dirty" power plants)

Planning and permitting
Important elements:
 * Siting (finding a site with i.e. good wind, proximity to onshore transmission capacity, favorable regulatory regime and the right conditions in terms of water depth, soil conditions etc.)
 * Preliminary technical plan
 * Environmental impact assessment
 * Wind measurement
 * Applications for various permits required by local authorities
 * Communication with the public and stakeholders to ensure support for the plans
 * Predictions of the yield of the plant
 * Financial modelling
 * Financing

In many cases, planning and permitting is done by specialized project development companies that do not intend to own and operate the plant, and that do not have the financial resources to do so. In other cases it is undertaken by utilities or independent power providers ("IPPs").

The planning and permitting phase can cost >$10 million, take 5–7 years and have an uncertain outcome. The industry puts pressure on the governments to improve the processes, and some governments are responding by streamlining them (e.g., UK, Ontario).

Procurement and construction
The owner of the wind farm typically procures it under a few, major EPCI contracts):
 * Wind turbines
 * Marine structural elements
 * Foundations -- required for fixed-bottom turbines, but not for floating turbines.
 * Electrical cables (within the farm and to onshore connection point)
 * Offshore Transformer substation(s)

All these items have special requirements for and special challenges in the offshore environment. For instance, turbines are much less accessible than offshore, and thus Reliability is more important than for an onshore turbine.

Foundations transfer the loads from the turbine into the seabed. Major issues for offshore foundations include the need for special installation vessels and the resultant risk and costs of waiting for weather windows. Technology exists to install without use of offshore crane.

Operations and maintenance
After commissioning of the offshore wind farm, the operations and maintenance phase commences.

A control center uses weather forecasts to predict electricity generation and interfaces with the Transmission system operator to integrate the electricity into the grid. The control center also monitors and controls the individual turbines and other components of the plant.

A maintenance organization performs maintenance and repairs of the components, spending almost all its resources on the turbines. Access to turbines is by helicopter or service access vessel. Some wind farms located far from possible onshore bases have service teams living on site in offshore accommodation units.

Aesthetics
One of the main concerns with wind power is aesthetics. Some may find these large rotating blades extremely distracting and can take away the beauty of the land. Offshore wind power does not have this issue. In most cases, these turbines are created very far from land (at least 10 miles) and can rarely been seen. Noise is not necessary an issue when it comes to Offshore Wind Power due to the remoteness of each turbine. http://www.awea.org/faq/wwt_offshore.html