Flatpack wood turbines could give wind power a green boost

While disposing of them at the end of their life poses additional problems: blades made from fibreglass and carbon fibre are particularly tricky to recycle, meaning they tend to end up in landfill.

Now however, there are hopes that the next generation of towers and blades could solve the problem of how to make wind-powered renewable energy more environmentally friendly.

And the solution, according to a spate of new start-up businesses, could lie with good old-fashioned trees, laminated wood and ‘Ikea-style flatpack’ pieces, all stuck together with glue.

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The idea of wood-based wind turbines has taken hold in north Europe, where firms are on the verge of scaling up prototypes and early versions.

In Germany, start-up firm Voodin Blade Technology is working with Finnish timber specialist Stora Enso to develop wooden turbine blades. Currently in production is a 20m blade for a 0.5 megawatt turbine, with plans for an 80m version fitted to a turbine up to 6 megawatts in capacity – the size used in commercial farms.

While in Sweden, another start-up, Modvion, is driving forward its idea of constructing turbine towers using sections of laminated wood.

Lightweight and easy to transport, it says the laminated veneer lumber (LVL) modules can be carried on the back of a lorry and slotted together on site – like a giant flatpack kit - helping to avoid road closures and enabling more parts to be transported in a single journey.

Because the engineered wood it uses is stronger than steel at the same weight but less expensive to produce, it opens the prospect of wood being used to construct ever taller towers – meeting a key demand of the wind energy sector and without the need for costly reinforcements.

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Taller towers can harness stronger winds, meaning more cost-effective energy production. However, the tower construction costs soar when made using steel. While according to Modvion, a timber wind tower solves a host of environmental issues, including generating 90% less carbon dioxide emissions during construction.

Then, once at the end of its 25-30 years lifespan, the tower can be taken apart and the wood reused, such as for high-strength beams for the construction industry. Eventually it can be recycled further, for lower spec uses like partition walls before being further reduced to paper.

The firm says using a renewable material like wood means their towers can also act as a carbon sink, reducing emissions for the entire turbine by 30%.

It adds: “The life cycle emissions from a 110m tall wind turbine tower of steel is approximately 1,250 tonnes of carbon dioxide.

“The corresponding tower in wood emits 90% less emissions, which means around 125 tonnes of carbon dioxide.

“The wood is also storing carbon and therefore acts as a carbon sink.

“When you take that into account, the tower reduces and stores more CO2 than it emits.”

Whereas steel towers require hundreds of bolts that need regular inspections, the modular wooden towers are joined together with glue.

Although the Modvion wood towers are still being fully developed, UK-based energy company Renewable Energy Systems (RES) has signed a letter of intent to use around 20 towers a year from 2026 to 2036.

RES has either developed or constructed 21 wind farms in Scotland with a total generation capacity of 597MW. They include Blary Hill Wind Farm near Glenbarr, and Freasdail Wind Farm, both on the Kintyre Peninsula, and the proposed 21-wind turbine Bloch Wind Farm, planned for a site alongside the existing Solwaybank Wind Farm near Langholm, Dumfries and Galloway.

Modvion erected its first 30m wooden wind turbine tower on an island near Gothenburg in 2020. It says is set to produce a full-scale commercial 150m wind turbine tower made using LVL produced from Scandinavian spruce.

As well as helping to make the sector greener, the switch to wood could help tackle issues surrounding how steel manufacture can keep up with soaring demand for wind turbines – the market is expected to double in value by the end of the decade.

A spokesperson for Modvion said Scotland with its large supply of Sitka spruce could be well placed to make its own tree-based wind turbines.

“We currently use Scandinavian spruce but any soft wood works, including Sitka spruce. Scotland is very much possible for supplying raw material for wooden towers.”

She added that the towers are unlikely to suffer from harsh Scottish winters. “We are based in Gothenburg, Sweden, which can compete with Scotland for rainy and harsh conditions.

“Our first wind turbine tower was built on the island of Björkö, close to Gothenburg and has withstood the harsh coastal climate for coming up to three years.

“Wood is of course sensitive to water so we protect the tower with a weather protection coating, the same that is used for offshore wind turbines, to ensure that water does not get through to the wood.”

She added: “Scotland is an interesting market although when we would enter the market is not certain.”

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Dr Dan Ridley-Ellis, head of the Centre Wood Science and Technology at Edinburgh Napier University, said: “This not a completely new idea – people have been building wind turbines and elements out of wood before now.

“But this is made out of a kind of engineered wood, manufactured in a way to give it better properties.

“This particular kind of engineered wood, LVL, is rather like plywood but instead of the pieces going at 90˚ to each other, different layers all go in the same direction.

“It has been used for around 30 years and while it can be seen in bits of buildings - such as the staircase at the John Hope Visitor Centre at Royal Botanic Garden Edinburgh - it is relatively new for large scale construction.”

There is some uncertainty among engineers, however, over how effective LVL may be in the construction of wind turbines, he added.

“We don’t have long experience of making wind turbines, whatever material is used. There is a lot of general uncertainty because they are relatively new kind of structure.

“The more that are made and the more people see them working, then they will begin to trust it.

“You don’t want to be building a lot of these in remote areas and find you have to go out regularly to carry out maintenance that you’re not expecting.”