The UK must ensure it replaces older onshore wind farms with newer turbines as they reach the end of their operational lives if it is to secure enough low-cost power capacity to meet climate change targets, RenewableUK has warned.

A report today by the trade body explains that more than 8GW of existing onshore wind capacity, which currently generates nearly a fifth of the UK's renewable electricity output, could be retired over the next two decades.

The group added that new policies are therefore needed to enable the replacing or 'repowering' of these older turbines as they reach the end of their operational lives, such as setting a framework to encourage councils to grant planning permission for such projects.

The report warns the UK faces a low carbon electricity generation gap of up to 18 per cent of current demand by 2030, and that if the government fails to support 'repowering' or replacing existing onshore wind turbines that gap could grow even wider.

Meanwhile, recent government figures show the UK is currently on track to overshoot its own carbon budgets in the late 2020s and early 2030s, as it seeks to decarbonise in line with statutory targets. Those targets could be further strengthened in the coming months if the Committee on Climate Change recommends the UK should replace its target to cut emissions 80 per cent by 2050 with a new net zero emission goal.

RenewableUK chief executive Emma Pinchbeck said repowering older onshore wind turbines was a low-cost option for plugging the looming low carbon electricity gap and helping to cut emissions.

"This should be an easy win on climate change that cuts emissions and secures cheap power for consumers," she said. "Without new policies from government we risk losing huge amounts of renewable energy, so repowering onshore wind is critical to cutting our carbon emissions and closing the looming energy gap. Upgrading our infrastructure with modern onshore turbines is good for consumers, as onshore wind is the cheapest form of new electricity available, and brings investment to communities around the UK."

The UK's first commercial wind farms were developed in the 1990s and built to operate for around 20-25 years. Moreover, analysis by the Energy and Climate Intelligence Unit (ECIU) last year highlighted around 750 turbines across almost 60 UK sites installed around the turn of the millennium which are scheduled to reach the end of their operational lives in the next five years.

ECIU estimated that repowering existing onshore wind farms could increase UK generating capacity by more than 1.3GW compared to dismantling them, saving UK billpayers billions of pounds in the process.

In its own report today, Renewable UK argued replacing older turbines with more efficient models could mean having to install fewer turbines than currently operate at each existing UK wind farm site. However, it also advocated for the government to consider enabling a range of supportive policies that could allow for the upgrading turbines that are already operating or let existing wind farms operate for longer than originally planned.

The report sets out an 'optimum scenario' which would see 12GW of replacement onshore wind capacity installed - with more powerful turbines taking the place of older ones - which could help fill the capacity gap by powering almost eight million homes a year.

Under its 'low scenario' however, the report envisages 2.76GW of new onshore wind capacity being installed due to fewer planning applications being approved and smaller turbines being used, which would mean a net loss of 5.5GW compared to today.

Concerns remain within the industry that while repowering projects are likely to prove cost effective they could be seriously stymied by the planning system, which can place stringent limits on the height of new turbines and lead to significant project delays. Developers also face the on-going challenge associated with the government's refusal to let onshore wind farms compete for contracts, which means they have to find long term customers for new projects or take the financial risk of selling power on the wholesale market.

The report follows comments yesterday from chief executive of the National Infrastructure Commission, Phil Graham, who reiterated his calls for the UK to focus on building enough renewables capacity to meet 50 per cent of domestic electricity needs by 2030.

A tweak to planning rules published by the government last summer has potentially opened the door for developers to start securing approval from local planning authorities to repower wind farms, even if securing finance for new projects can prove a complex undertaking.

Changes set out in the government's revised National Planning Policy Framework last year state that councils should approve applications to repower existing wind turbines "if its impacts are (or can be made) acceptable".

The Department for Business, Energy, and Industrial Strategy (BEIS) was considering BusinessGreen's request for comment at the time of going to press.

Replacing old turbines with much more efficient models should play a key role in the decarbonisation of the UK's power grid over the next decade. New turbines are more cost effective, local opposition to repowering projects is likely to be limited given the sites are already in use, and projects should be able to be delivered quickly. Moreover, the emissions and clean electricity gap the UK is now facing urgently needs closing. But it remains to be seen if the government and local councils will get the memo.