Rewind to 2002 for a minute. Eminem’s The Eminem Show is the best-selling album globally, Brazil has just lifted the men’s football World Cup (again), and Nokia’s 3310 is helping usher in a new era of mobile communication. That old ‘brick’ phone might seem rudimentary by today’s standards, but it was game-changing technology back then. The same can be said of the windfarms that started appearing in the UK around the same time.

Indeed, 2002 was a stellar year for the country’s burgeoning renewables sector. A relaxation of planning laws and improvements in turbine technology saw wind energy truly take off. But, unlike those old 3310s, which were soon upgraded, many early turbines are still in action – and nearing the end of their working lives.

Wind turbine technology has made huge leaps forward since 2002. Like phones, modern versions are more efficient and smarter. They can now, for instance, angle their blades to optimise wind energy. These efficiency gains present a major opportunity for the UK as it replaces – or to use industry lingo, ‘repowers’ – its ageing fleet.

“What we’re seeing where we have repowered is an ability to more than double output from existing sites,” says Matthew Clayton, managing director of Thrive Renewables, which has funded dozens of the UK’s windfarms. “That’s exciting.”

The UK needs to roughly double its current onshore wind capacity by 2030 – from 14GW to 30GW – to meet clean energy targets. If Thrive’s experience is anything to go by, that ambition could largely be met by replacing old turbines with newer ones.

“Almost without building any new windfarms, you could pretty much achieve onshore wind’s [required] contribution through repowering,” says Clayton. “That’s not to say that we won’t need additional sites, because we do.”

It’s possible, even, to take turbines away from the landscape while boosting output. Thrive achieved just that at Caton Moor in Lancaster, northern England, where it replaced 10 old 300KW turbines with eight 2MW versions.

“We generate seven times as much power from that site as we did before, despite reducing the number of turbines,” says Clayton. “If you apply those ratios to other sites across the country, that 30GW begins to feel entirely achievable.”

Repowering has benefits beyond simply boosting output. Existing sites already have grid connections and planning consent. “A repowering project has the advantage of being in an area where the community already understands onshore wind,” says James Robottom, head of policy at RenewableUK. “People are used to seeing turbines and there’s often a community benefit fund set up.”

We generate seven times as much power from the site as we did before, despite reducing the number of turbines

Such funds enable communities to reap financial rewards from wind installations. For instance, a single turbine in Lawrence Weston, an area of Bristol, generates up to £300,000 of electricity per month, which is sold to the grid. Profits from the community-owned installation – funded via a loan from Thrive – go towards local poverty alleviation.

“It has a positive effect on the environment and helps to address social injustice,” says Mark Pepper, development manager at the residents’ group Ambition Lawrence Weston. “So, you have a social win and an environmental win.”

The Lawrence Weston installation is the largest onshore wind turbine in the UK, but probably not for much longer. Last July, the new government lifted the de facto ban on onshore wind – in place since 2015 – paving the way for more windfarms across the country. Future projects will invariably use new turbines, which are generally bigger than previous versions, albeit not discernibly.

At Caton Moor, for instance, the new turbines are only five metres taller than the ones they replaced. “People shouldn’t be worried about turbines the size of the Shard going up everywhere,” says Clayton, though he acknowledges that some repowered sites have seen turbine heights increase by 25m.

The increased size of new turbines presents a challenge as well as an opportunity when it comes to repowering.

“When you try and transport turbines along the UK’s windy roads, you hit an upper limit of the size of the blades you can get to site,” explains Clayton. It’s why, he says, we need more windfarms – because not every site will be suitable for repowering.

You have a social win and an environmental win

“It’s very case by case,” agrees Rowbottom. “That’s what makes it difficult to do any kind of accurate prediction about capacity growth [from repowering].”

Another stumbling block more generally is a lack of grid capacity. “We need to see significant investment in grid infrastructure,” says Rowbottom. “Although it is encouraging to see more work being done to address grid connections challenges.”

Repowering also creates an environmental challenge: what to do with all the old blades? Unlike modern versions, early iterations were not built with circularity in mind.

“Newer blades use materials that are far more capable of being recycled,” says Rowbottom. “It’s the old [fibreglass] blades that are tricky.”

Reblade, a company based in Scotland, has a solution. It turns defunct blades into useful new items, including overhead canopies for electric vehicle charging stations, with the first ones set to be installed in Dundee.

The business has also partnered with Thrive to turn blades from one of its repowered sites into bespoke dining tables and bike shelters.

“This is the green energy circular economy in action,” says Steven Lindsay, director of Reblade. “We’re confident that this approach can accommodate a majority of the first-generation wind turbine blades due to come down in the UK and Ireland over the next 10 years. We can take as many blades as the wind industry can give us.”

That’s just as well because there will be plenty of them. The UK is due an upgrade.

Main image: AscentXmedia