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Coming of age, what to do with mature wind farms? Extend, repower or decommission?


At a time when many nations are expecting an explosion of new leasing rounds to meet the gap left by the phasing out of fossil fuels (and in some jurisdictions, nuclear power), it might seem odd to consider the ‘end of life’ options for wind farms – whether lifetime extension, repowering or decommissioning. However, wind turbines have an operational lifetime of 20-25 years. For the original offshore developments in the North Sea, this may be shorter as technology, fabrication and construction knowledge has developed rapidly over the past 20 years.

Already, we have seen the UK’s first pilot offshore wind project, Blythe Offshore (commissioned in December 2000) decommissioned in 2019, with one (of the two) turbines recycled and the other being re-erected as a training facility in Blythe Harbour, so this is not a topic which is far from existing operators’ minds.

This article briefly considers the options available for UK wind farms (lifetime extension, repowering or decommissioning) that are approaching the end of their (initial) operating life.

Lifetime Extension

The availability of the lifetime extension will depend on the existing condition and design-life of the wind farm. In principle, no major aspects of the wind farm are replaced as part of the extension, but instead, repairs and maintenance take place.
It is thought that lifetime ­extension offers the lowest investment cost of the three options, preserving the farm’s annual electricity production for an ­additional 10 or even 15 years (with further investment). As offshore wind learnt much from the pioneers in offshore oil and gas, there is ­significant scope of lifetime extension (which has consistently added 5, 10 or even 20 years to predicted asset lifespans for assets in the North Sea).

Industry commentators suggest that half of Europe’s existing wind farms will have their lifetime extended for 5-10 years once they reach 20 years of operation.


In essence, ‘repowering’ a windfarm means replacing the older (smaller of 1-3MW) turbines with next-generation (larger) turbines which now reach 6-8MW and even 10-15+MW in the next 15 years.

It is thought that repowering might reduce the number of ­turbines by a third while multiplying electricity output by as much as three times.

According to industry commentators, partial repowering (that is, not undertaking major infrastructure works such as re-piling/new subsea caballing) offers a maximum return to developers, extending a wind farm’s lifespan by 25 years and increasing existing developments’ electricity generation by as much as 34,000 GWh. Full repowering offers a lower return, as infrastructural changes are required as opposed to merely replacing turbines.

In theory, it could become common practice that established wind farms are routinely repowered with developments in floating wind/fixed base construction techniques allowing farms to continue towards the middle to end of the century, after all, offshore wind doesn’t face the greatest challenge of fossil fuels – finite supply.


As a last resort, wind farms may be decommissioned by completely removing the farm’s foundations, turbines and cables. This is the least cost-effective option as it does not create future revenue and involves a greater risk of delays and extra costs. It is also, perhaps surprisingly, the option with the highest environmental cost as turbine blades are difficult to recycle and the removal of subsea cables and installations will require huge amounts of energy, almost all of which is currently generated by fossil fuels.

In the UK, the process of decommissioning is governed by Sections 105-114 of the Energy Act 2004, which imposes obligations on those responsible for offshore installations to prepare and carry out a decommissioning programme. The regime aims to reduce the risk of companies defaulting on their liabilities whilst ensuring that it does not impose obstacles to new offshore clean energy developments.

In support of this, the Crown Estate (as the owner of the sea bed in the UK) works in tandem with the Government to reduce duplication of requirements and simplify the scheme, providing a ‘one-stop shop’ for decommissioning. As such, developers are only required to prepare and submit one decommissioning programme to the Department of Energy and Climate Change (DECC).

Developers are encouraged to consider decommissioning plans at an early stage, and in any case, before construction begins. The plan should be in line with Government decommissioning standards and should cover proposed decommissioning measures, environmental impact assessment, costs, proposed financial security provisions and post-decommissioning site management, amongst other areas, which are detailed in the Government guidance.

Current UK Policy

The scheme under the Energy Act 2004 endorses a “polluter pays” principle for decommissioning (imported from the Petroleum Act 1998).

However, in the Government’s Ten Point Plan published in November 2020, the Government set out plans to deploy 40GW of offshore wind power by 2030 and there are concerns that the decommissioning of existing farms could result in missing the target.

It is thought that around 1,600 wind turbines are set to be decommissioned in the UK by 2030. Thus, whilst the Energy Act scheme provides a decommissioning framework, it seems that Government policy is currently far more focused on expansion, without (perhaps) much consideration for how decommissioning will come into play and affect targets.

Does this suggest that lifetime extension and repowering will become the norm? Time will tell, but if the UK is to reach net-zero by the middle of this century then offshore wind will have a substantial part to play and the UK government will need owners and operators to maximise offshore wind capacity, not decommission it.


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