Social acceptance rather than technology barriers will dictate the size and power limits of future onshore wind turbines, said senior industry executives.

Gaining acceptance for larger and taller turbines will be a decisive factor as OEMs power-up to lower the cost of energy and tap into lower wind speeds, with GE the latest to unveil a 6MW model earlier this week amid ongoing debate over how large onshore turbines can – or should – grow as they reach capacity ratings once seen as stretching for offshore machines.

Danielle Merfeld, chief technology officer for GE Renewable Energy, told a panel of the Wind TV conference at WindEnergy Hamburg: “Blade length and tower height, from a society perspective [of acceptance of] scale and noise – those are likely to be the limits of the interest from a customer perspective”.

That view was supported from the customer side by Katja Wünschel, operations chief for onshore wind and PV in Europe & Asia-Pacific for RWE Renewables, who said: “The limit is not so much the technology, there is probably even more room to grow.

“Social acceptance will be the natural limit. There will be opponents who say ‘I don’t want to have this gigantic turbine next to me’.”

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Recharge has over the last few years reported a growing influence on policymakers of a vocal minority of onshore wind 'nimbys' in key European markets such as Germany, France and the UK, with increasing turbine height and rotor size a focus of that opposition.

Wünschel said the issue is a particularly live one in relation to project repowering in the European market, where some of the continent’s best wind resources are currently tapped by “little, kilowatt-size” machines.

The latest generation of technology opens the potential for replacing them with “a handful of very large scale turbines. Yes it’s larger, it’s taller but it’s fewer – and we could make it much more efficient.

“In Europe we have to go high, we have to go large and see what at the end is the number of turbines that’s locally accepted, and fits to the restricted space we have.”

Permitting woes

But while Wünschel said the “technology’s there and I think we can work with local acceptance” the problem lies with a permitting framework that in most European countries means “no difference between repowering and new-build”, according to the RWE executive.

“Repowering – it’s a nice name but at the end you start from scratch [and] you go through the same circle of permitting and development process,” she said.

Whether greenfield or repowering, Wünschel said the latest generation of turbines are being locked out of projects that have to specify their technology choice “much too early” in many countries where obtaining consent takes far too long.

It’s not fit for purpose that technology is faster than the permitting process.

“It’s nice that a 6MW turbine is available soon – but what if my project is locked in a permitting process to turbines that will be outdated

“It’s not fit for purpose that technology is faster than the permitting process.”

Wünschel said “the clock is ticking” for open-technology permitting, and for reforms brought forward by the EU that require consent to take no longer than three years for new projects and two for repowering.

Maturing industry

Anders Nielsen, chief technology officer for Vestas, said the focus on size of turbine as the main measure of progress would lessen as the industry matures.

“Going larger and larger, from a technical perspective of course we can do that.

“The question is, does it make sense from a business perspective, a customer perspective.”

Nielsen said with very large turbines able to address only a limited part of the market, OEMs would have to be adept at serving multiple segments and find new ways to add value.

One example is modularity, which can not only tailor products to specific customer needs but reduce risk as technology evolves, said Nielsen.

“A new product always carries a risk. To mitigate that risk I need to carry over as much technology as possible from the platform I have been using before.”

GE Renewable Energy’s Merfeld agreed that “size is not the only factor we should be considering”, pointing to technical innovations that can add value and lower cost such as jointed blades, digitalisation and potential logistical game-changers such as 3-D printing of towers at sites.

“Value is not only scale – how do we extract more value from within the envelope we have?” Merfeld asked.

“It’s not necessary for that envelope to grow for the value to increase.”