Floating wind-farms – unlocking energy on the ocean

floating wind picHarnessing the world’s wind has developed into one of the most successful methods for generating renewable electricity. However in many places increasing onshore wind capacity is running into challenges. Opposition from concerned residents over the noise, shadows, and effects on views and species such as birds has lead, rightly or wrongly, to many dead-ends in on-shore wind development.

The increasingly popular alternative is to move the farms offshore. Offshore wind is a far more expensive method of developing wind capacity but is met with far less opposition. The UK currently gets approximately 5% of its electricity from offshore wind, including from the London array, the world’s largest windfarm at, 630 megawatts, opened in 2013. Much of Europe is benefitting from offshore wind and considerable expansion of capacity is underway. But the potential is limited by the construction feasibility, constraining development to sea depths of less than 200ft.

But, as ever, necessity is the mother of all invention, and new and exciting work is underway to develop “floating windfarms”. These could truly unlock the energy potential of the ocean, with a far greater area of sea-bed on which to exploit those ocean winds.

The great ocean, however, also presents great challenges. Firstly, offshore wind is pricier than onshore and floating farms are expected to be even more expensive than conventional offshore wind. This is because the floating platforms require more steel to be anchored to the deep seabed and each other than a fixed platform system does. The price will change in future as whilst fixed offshore wind, an established technology, is working to lower costs with each development, floating farms are only just emerging from the test phase. According to Bloomberg New Energy Finance, by 2020, floating wind farms will likely cost $9m per megawatt whilst the fixed-foundation farms will cost $4m per megawatt.

Secondly, the ocean presents new ecological challenges that threaten wind power’s environmentally-friendly credentials. There are the traditional concerns over the effect of the blades on birds and whether the noise and vibrations will affect species, in this case marine life. Added to these is the new risk of entanglement. This is especially a concern for whales because, although they have very good sonar, the network of anchoring cables and power cables to transmit the electricity onshore could still pose a threat. Analysing these threats suggests optimism as studies conclude most birds avoid wind turbines and there have been no known incidents of marine mammals getting tangled in existing structures such as mooring lines and offshore drilling platforms. Nevertheless, the delicate and complicated marine ecosystem must be treated with equal delicacy and caution to allow progress.

One group making progress is Statoil who are planning to build the world’s largest floating wind farm off the coast of Scotland. The 30 megawatt pilot, due for completion in 2017, would include 5 turbines and draw from the work of an earlier demonstration project of one turbine off the coast of Norway. The aim of the pilot is to show that floating farms can deliver cost effective and low risk options for the future. There are currently around 40 floating windfarm projects around the world at varying stages of development, with none yet completed. But, with so much excitement and energy being put into this new technology, it seems likely it will be a big contributor to renewable electricity in the future.

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