Around the world renewable energy targets are being set and the rush is on to meet them with solar energy, geothermal energy, tidal, wave, biomass, hydro-electric and wind power growing at a rapid rate.

Wind power is at the forefront of the renewable energy push, mostly through onshore wind farms. But more and more we are seeing proposals put forward to develop wind farms offshore. The advantages for doing so are many and sizable.

Firstly with any proposed wind power project come opposition of some form or another from local residents. Often this opposition comes in the form of environmental concerns, often these concerns mask the real reason for the opposition which stems from a "not in my backyard" mentality. Other reasons include a noise issue and complaints that the wind turbines look ugly.

Offshore wind farms are sited beyond sight and hearing ranges, are out of the flight paths of nesting birds and bats and provide far fewer environmental concerns. Add to this the fact that the potential expansion of the wind farm 20km offshore is enormous (bordering on limitless) and you have a source of renewable energy with huge potential.

The downside to offshore wind power is largely one of cost. Every onshore wind turbine is expensive to erect. Building a wind turbine in deep water 20km or more out to see adds huge expenses to the project with the requirement of platforms, ballast and anchoring to think of, not to mention accessing the turbines.

Proposed Major Offshore Wind Farms

All of these factors have come into play with the increasing number of offshore wind farms that are proposed or in place around the world. Here is a selection of some of the largest offshore wind farms that could be producing clean power by 2010.

Greater Gabbard Offshore Wind Project - England

This is a proposed 504MW capacity wind farm that has been proposed for 23km in the North Sea off Egland's Suffolk Coast. The wind farm will comprise 140 wind turbines and will produce enough electricity to power up to 415,000 homes. The Greater Gabbard wind project is a joing venture partnership between Airtricity and Fluor Corporation. The Greater Gabbard project is expected to be completed in 2011.

London Array, England

The London Array is a proposed 1,000MW wind farm that will be built 20km off the Kent and Essex coast of England. This wind farm will comprise 341 wind turbines and will produce enough electricity to power up to 750,000 homes. The investors of this project until recently formed a joing partnership of DONG Energy, E.ON Power and Gas and Shell WindEnergy. However Shell have withdrawn their involvement and their investment dollars putting the completion date of the project into doubt. The London Array project was proposed for completion in 2010, but with Shell's departure the date is now unclear.

Arklow Bank Wind Farm, Ireland

This is a proposed 520MW project that will be built 10km off the coast of Ireland and will comprise 200 wind turbines when fully completed. The first phase of the project, developed by Airticity, has seen the installation of 7 wind turbines producing a capacity of 25MW. The second phase has been put on hold indefinitely.

Cape Wind, Nantucket Sound

This is a proposed 400MW project that is planned to be constructed within 62 square kilometres in Nantucket Sound. The wind farm will be comprised of 130 wind turbines. The project is currently in the permitting stages and, if given the go ahead, could be in commercial production by 2011. The wind farm could have the capacity to provide electricity to up to 400,000 homes.

NaiKun, British Columbia, Canada

This is an ambitious project is proposed for a maximum capacity of 1,750MW which would be capable of providing enough electricity to power up to 600,000 homes. The NaiKun wind energy project will be located in Hecaite Strait between Haida Gwaii and Prince Rupert on the British Columbia mainland. The intention is to construct the wind farm in five stages with construction of the first stage planned for 2009 and is expected to produce a capacity of 320MW. Approval has not yet been granted for the full 5 phases.

Robin Rigg Offshore WInd Farm, Scotland

More than simply proposed the 180MW capacity Robin Rigg Wind Farm is under construction at the moment. Construction of the onshore facilities began in 2007 and the 60 wind turbines that will comprise the project have been constructed since late 2007 with an expected completion date of 2009. The project is being developed by E.ON UK, a company that has had experience in successfully completing offshore wind farms.

Deepwater Offshore WInd Farm, New England, USA

A 420MW commercial wind farm will be constructed 45 miles off the coast of New England by Blue H Technologies BV. The turbines of this wind farm will be built on floating platforms that will be then taken out to their position and anchored. The technology that will be used by Blue H is called Submerged Deepwater Platform (SDP). The technology is innovative because it allows the wind farm to be sited in waters where the depth is greater than 50 meters.

Existing Major Offshore Wind Farms

Offshore wind farms are already commercially producing electricity in waters around the world. Here is a selection of wind farms that currently have a capacity of more than 100MW.

Horns Rev Wind Farm

In 2002 the Horns Rev Wind Farm was constructed off the west coast of Denmark. The wind farm sits in waters 14-20 kilometres out to sea in the North Sea. The Horns Rev wind farm comprises 80 Vestas wind turbines and has an annual electricity output of 600 GWh. The project was constructed by Elsam and in 2006, a 60% ownership of the project was taken over by Vattenfall. Elsam has since merged with DONG Energy who now owns the remaining 40% of the wind farm. (DONG Energy are one of the partners in the proposed London Array project). The goal of the Danish Government is to increase the wind power capacity from wind farms in Danish waters to at least 4000MW before 2030. The Horns Rev website can supply even more details.

Nysted Wind Farm

Another Danish offshore wind farm that is contributing to the goal of 4000MW before 2030 is the Nysted Wind Project. This offshore wind farm sits 10km off the east coast of Denmark and has a maximum capacity of 160MW consisting of 72 wind turbines. Like Horns Rev the Nysted Wind Farm was constructed by Elsam and is now 80% owned by DONG Energy with the remaining 20% owned by E.On Sweden. Visit the Nysted Wind Farm website for more information.

Egmond aan Zee

A Netherlands offshore wind farm with a maximum electricity capacity of 108MW was constructed in 2006 10km off the Dutch coast in the North Sea. This project was constructed by Nuon and Shell and during 2007 it produced more than 111 million kWh of electricity. The wind farm comprises 36 wind turbines, each with a 3MW capacity. Find out more about the project at the Egmond aan Zee website.

There are a number of smaller offshore wind farms that are producing electricity in commercial quantities. They include the UK offshore wind farms like the 90MW Barrow-in-Furness wind farm and the 90MW Burbo wind farm off the west coast of England, the 60MW North Hoyle wind farm off the coast of Wales and the 90MW Kentish Flats Offshore Wind Farm located in the Thames Estuary. Off the German coast is the 40MW Mecklenburg-Vorpommern wind farm and there is another 40MW Danish wind farm known as Middelgrunden.

Offshore wind farms are going to pop up in the waters around the world with increasing frequency. Major power developers like DONG Energy, Airtricity and E.On have proven that it is a commercially viable form of renewable energy and the projects are becoming more ambitious as the technology matures.