World’s tallest wooden wind turbine launched

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by Jonah Fisher, BBC environment correspondent in Skara, Sweden

Modvion Modvion Turbine TowerModvion

Engineers are working on building the world’s tallest wooden turbine tower

What is made from the same wood as a Christmas tree, glued together, manufactured in a factory in Sweden, and assembled later?

If that makes you think of flat-pack furniture and meatballs, you’d be wrong.

If you answered “wooden wind turbines,” you may be a visionary.

Using wood for wind power is the future, according to Swedish start-up Modvion, which has just built the world’s tallest wooden wind turbine tower.

“This has huge potential,” says CEO Otto Lundmann, looking up at the company’s brand new turbines a short drive outside Gothenburg.

The tip of the tallest blade is 150 metres (492 feet) high, and we are the first journalists to be invited to tour the inside. The 2-megawatt generator at the top has just started supplying power to the Swedish grid, providing electricity for around 400 homes.

Landman and Modvion dream of further developing timber and wind power.

The Limits of Steel

On the horizon near the Modvion project, several very similar looking turbines spin.

Like nearly all wind turbine towers around the world, the primary material used in wind turbines is steel, not wood. Steel is strong and durable, making it possible to build huge wind turbines and wind farms on land and at sea.

Modvion Modvion's Wooden Wind TurbineModvion

The blades and generators of this 150-metre wind turbine in Skara, Sweden are made from conventional materials.

However, steel is not without its limitations, especially in onshore projects.

As demand grew for taller turbines with bigger generators to capture stronger winds, the diameter of the cylindrical steel towers that support them needed to increase as well.

In a world of road tunnels, bridges and roundabouts, many in the wind industry say transporting those huge pieces of metal to turbine sites is becoming a real headache, effectively limiting the height of new steel turbines.

A chart showing recent and projected future growth in wind power capacity - from less than 200 gigawatts in 2010 to a projected 1,700 gigawatts in 2027.

Wooden turbine or sauna?

From the outside, there are few obvious differences between Modvion’s wooden turbines and their steel counterparts.

Both have a thick white coating to protect them from the elements, and the blades are made primarily from fiberglass and attached to generators that produce electricity when they spin.

It’s only once you step inside the tower that the difference becomes apparent: the walls are curved and finished in raw wood, much like a sauna.

Kevin Church/BBC Inside the TurbineKevin Church/BBC

Modvion’s Otto Lundmann shows Jonah the inside of a wooden turbine

The 105-metre (345-foot) tall tower owes its strength to 144 layers of laminated veneer lumber (LVL) that make up its thick walls.

Modvion claims that by varying the grain of each layer of 3-millimeter-thick spruce, it can control the strength and flexibility of the walls. “That’s our secret recipe,” says co-founder David Olivegren, a former architect and boat builder, with a smile.

In a factory outside Gothenburg, thin layers of timber are glued and compressed to create the curved sections, then these timbers are transported to site, glued into cylindrical shapes and stacked to create the towers.

“Wood and glue are a perfect combination. We’ve known that for hundreds of years,” Olivegren says. “Wood makes things lighter, so [than steel] We can build taller turbines using less material.”

Inside the Modovion factory

Modvion’s David Olivegren inspects modular wooden turbine towers at the factory.

Landman and Olivegren say a major selling point of their turbine is that using wood and glue allows the tower to be built as smaller, more easily transportable modules.

That would make it much easier to build very tall towers and transport parts to difficult locations, they say.

But more parts mean more trucks, people and time needed to complete the installation, says Dr Maximilian Schnipperling, head of sustainability at Siemens Gamesa, one of the world’s largest turbine manufacturers. He sees modularity as an “advantage” and wooden towers as a “good complement” to steel towers.

Siemens Gamesa’s efforts are focused on reducing the carbon footprint of the steel it uses, he says.

Inside the Modvion Tower, we were shown how the wooden modules are stacked and then secured together with glued steel fittings.

“The industry wants to build 300m turbines. [blade] “You need towers with tip heights, meaning more than 200 metres in height, and modularity makes that possible,” Landman says.

Inside the Modvion turbine

The turbine tower’s wooden components are glued on site.

Of course, steel can also be modularized and the cylinder can be cut into smaller pieces, but the extra labor required to bolt the pieces together increases both cost and maintenance.

One of Modvion’s investors is renewable energy giant Vestas, which has installed more wind turbines worldwide than any other company.

Jan Hagen, the company’s chief technology officer for North and Central Europe, told me there was “huge potential” in the market for tall turbines, and that wooden turbines were “particularly well suited” to fill that role.

“What’s interesting about this is that it combines an economically viable solution to a transportation bottleneck with a sustainable solution,” Hagen says.

Negative Carbon Footprint

While wind power is cheaper and cleaner than most other forms of electricity generation, making steel requires extremely hot furnaces that almost always involve burning fossil fuels, which means emitting carbon dioxide, a major cause of climate change.

Modvion says that using wood instead of steel completely eliminates the wind turbine’s carbon footprint, giving it a negative carbon footprint.

That’s because trees absorb carbon dioxide from the atmosphere while they are alive, and when they are cut down, the carbon is stored in the wood – it’s not released until the wood rots or is burned.

Modvion’s turbine tower was built using around 200 trees – the same kind of spruce used for Christmas trees – that the company says were grown sustainably, meaning more can be planted as they are cut down.

Average emission intensity of different electricity sources in Europe in 2020. Coal represents 850-1000 grams of carbon dioxide equivalent per kilowatt-hour. The others are natural gas (430), solar photovoltaics (11-37), wind (12-14) and nuclear (5.1).

SSE Renewables, one of the UK’s biggest wind power companies, told the BBC it was aware of Modbion’s work and was considering wooden towers as an alternative “technology” to steel, but many of SSE’s projects are at sea and can only be reached by huge ships, so the benefits of modular transport are less pronounced.

Modvion hopes to build another, even taller, turbine soon, and if all goes well, it plans to open a facility in 2027 capable of producing 100 modular wooden turbines a year.

“The industry is currently installing 20,000 turbines a year,” Landman said. “Our goal is that in 10 years’ time, 10 percent of those turbines — about 2,000 — will be made of wood.”

Additional reporting by Mark Poynting and Kevin Church

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