A Swedish start-up, Modvion, based just outside of Gothenburg, has just built the world’s tallest wooden wind turbine tower. “Using wood for wind power has great potential,” claims Otto Lundman, the company’s chief executive.
The wooden tower measures 150m (492ft) to the tip of the highest blade and has a 2-megawatt generator on top that has just started supplying electricity to the Swedish grid, providing power for about 400 homes. The dream of Lundman and Modvion is to take the wood and wind much higher.
On the horizon, near the Modvion project, several very similar-looking turbines are turning. Steel, not wood, is the key material for them, as it is for almost all of the world’s turbine towers. Strong and durable, steel has enabled huge turbines and wind farms to be constructed on land and sea, but steel is not without its limitations, particularly for projects on land.
As demand has grown for taller turbines that harvest stronger winds with larger generators, the diameter of the cylindrical steel towers to support them has had to grow too. In a world of road tunnels, bridges and roundabouts, many in the wind industry are saying that getting those huge pieces of metal to turbine sites has become a real headache, in effect limiting the height of tall new steel turbine towers.
There is little obvious difference between the Modvion wooden turbine and its steel cousins. Both have a thick white coating to protect them from the elements and blades made primarily from fibreglass attached to a generator, which produces electricity when it turns. It’s only when you go inside the tower that the differences become clear. The walls have a curved raw wood finish, not unlike a sauna.
The 105m (345ft) tower’s strength comes from the 144 layers of laminated veneer lumber (LVL) that make its thick walls. By varying the grain of each of the 3mm-thick layers of spruce, Modvion says it has been able to control the wall’s strength and flexibility. “It’s our secret recipe,” says company co-founder, and former architect and boat builder David Olivegren, with a smile.
At the factory, on the edge of Gothenburg, the thin layers of wood have been glued and compressed together to make the curved sections. Those pieces are then transported to the site, glued together into cylinders, and then stacked on top of each other to make the tower.
“Wood and glue are the perfect combination, we’ve known that for hundreds of years,” Olivegren says. “And, because using wood is lighter than steel, you can build taller turbines with less material.”
Lundman and Olivegren claim that their turbine’s big selling point is that, by using wood and glue, towers can be built in smaller, more easily transported modules. That will make it much easier to build really tall towers, they say, and to take the pieces to challenging locations.
However, Dr Maximilian Schnippering, head of sustainability at Siemens Gamesa – one of the world’s largest turbine manufacturers – says more pieces are likely to mean more trucks, more people and more time to complete the installation. He considers the modular system “an advantage” and that wooden towers can “nicely complement” steel towers. Siemens Gamesa’s efforts are focused on reducing the carbon footprint of the steel it uses, he says. (His reactions are hardly surprising considering his whole focus in on steel.)
“The industry wants to build turbines with a 300m blade tip height, which means a tower which is 200m or more in height. With modularity you can do that,” says Lundman.
Steel could, of course, be modular too, with the cylinders cut up into smaller pieces, but the extra effort needed to then bolt the pieces together adds both to costs and to maintenance.
One of the investors in Modvion is renewable energy giant Vestas. It has installed more wind power capacity around the world than any other.
Jan Hagen, its chief technology officer for northern and central Europe, tells me they see “tremendous potential” in the market for taller turbines, with wooden turbines “particularly well suited” to play a role. “What we find interesting about this is that it is a combination of an economically viable, and sustainable, solution that addresses the transport bottleneck,” Hagen says.
Although wind power is cheaper and cleaner than almost all other forms of electricity generation, making steel involves extremely hot furnaces and, almost always, the burning of fossil fuels. That means substantial CO2 emissions – the main driver of climate change.
Modvion says using wood instead of steel eliminates the wind turbines’ carbon footprint entirely, making them carbon negative. Trees take carbon dioxide out of the atmosphere when they are alive and, when they are chopped down, the carbon is stored in the wood. As long as the wood doesn’t end up rotting or being burned, the carbon is not released.
About 200 trees went into Modvion’s turbine tower. They were the same species – spruce – that is used for Christmas trees and the company says they are farmed sustainably, meaning, when they are harvested, more are planted.
Modvion says it is hoping to build another even taller turbine soon and, if all goes well, it will open a facility that will produce 100 wooden modular turbines a year by 2027.
“The industry is currently putting up 20,000 turbines a year,” Lundman says. “Our ambition is that in 10-years-time 10% of those turbines – about 2000 – will be wooden.”
Another great example of what human innovation can produce, if we only put our minds to it. A breath of fresh air against a backdrop of myopic and stupid political climate change deniers.
