Wind power: Wooden turbines could make industry more sustainable

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Sections of a timber wind turbine tower under construction at Modvion’s manufacturing facility

Modvion

The following is an extract from our Fix the Planet newsletter, a weekly email about solutions to the climate crisis.

In the UK, onshore wind has been stuck in a bit of a time warp. In England, only a handful of new onshore wind farms have been built since 2015, when the UK government tightened planning rules governing the technology, choking off new projects. (Devolved nations have different rules, with Scotland planning to double its onshore wind capacity by the end of the decade.) That means many turbines dotted around the English countryside are at least a decade old and, frankly, looking rather tired.

From this perspective, it would be easy to assume that wind power is a slow-moving industry – that the turbines installed 25 years ago look the same as the turbines rolling off production lines now. But away from the quagmire of English onshore wind, excitement is afoot. Start-ups are devising new and better designs for the next generation of wind turbines. And one of the most promising ideas is to turn trees into turbines.

Troublesome materials

Traditionally, wind turbines have been made from a mix of different materials. The towers are generally constructed from steel or concrete, while the blades tend to be made from epoxy or fibreglass-reinforced polyester.

Steel towers are energy-intensive to produce, while the blades mostly can’t be recycled and so often end up in landfill at the end of their life.

There’s also a size problem. Taller turbines can harvest wind more efficiently, but the construction costs for steel towers increase with height. Transporting and installing turbines also becomes an expensive headache the bigger the towers become.

That problem has prompted wind companies to start designing better turbines.

Timber towers

Swedish start-up Modvion has developed a system to build turbine towers using sections of laminated wood.

Timber towers are lighter than steel and can be constructed in sections to be slotted together on site. This makes taller, more powerful turbines cheaper and easier to transport, says Erik Dölerud, an engineer at Modvion. “The whole market is going towards tall towers, and the taller the towers get the greater this basic advantage of timber becomes,” he says. “So, it’s definitely a cost-effective solution for those installations.”

Plus, producing a timber tower instead of a steel one generates 90 per cent less carbon dioxide emissions, according to Modvion.  And when the turbine comes to the end of its life, the modular segments from the tower can be reused.

Dölerud says the timber from decommissioned towers could be used as load-bearing beams in the building industry, then after that they could become partition walls and then paper. “That’s basically our vision – to have a six or seven step cascaded reuse of the material, for many hundreds of years, so that we get as much benefit out of each and every cellulose fibre before we return it to the atmosphere,” he says.

The firm already has one 30-metre tower up and running on the Swedish island of Björkö, which was erected in 2020. The pilot project helped the firm catch the attention of turbine maker Vestas, which invested in Modvion last year.

Now work is underway on a 100-metre-tall turbine for Varberg Energi, which is due to be completed next year and should pave the way for commercial rollout of timber towers. Eventually, the towers could reach heights of up to 150 metres. “The end goal is to be a leading global supplier of wind turbine towers in the 2030s,” says Dölerud.

Inside a timber tower

Inside a timber tower

Modvion

Wooden blades

Meanwhile, German start-up Voodin Blades has a vision for wind turbines to be built with wooden blades, which are lighter and easier to dispose of than fibreglass blades.

It is building its first 20-metre-long blades, which will be installed on a test turbine with a capacity of 0.5 megawatts in Warburg, Germany, by the end of the year. Work is also underway on an 80-metre-long blade that could be fitted to a turbine up to 6 megawatts in capacity, the size used in commercial farms.

In November, the company announced a partnership with Stora Enso, a Finnish firm that manufactures paper, pulp and other forest products. Stora Enso is supplying its laminated veneer lumber (LVL) to make the blades.

Stora Enso – which is also supplying timber to Modvion – claims its LVL is twice as strong as steel in proportion to weight and can perform just as well as fibreglass in a turbine blade. “This is a strong material, a lightweight material, that reproduces itself,” says Saki Boukas, who leads Stora Enso’s timber division.

Eventually, turbines could be made from wooden towers and wooden blades, says Dölerud. “I think it’s a very good idea,” he says. “I think that structural timber should be used for more applications than it currently is. It’s a high-end engineering material, and it should be used for more high-end engineering applications.”

Stumbling blocks

So, what’s the catch? Perhaps the biggest challenge is convincing risk-averse engineers to take a chance on timber, says Boukas. “Technology-wise, I don’t see any issues. It’s known technology, and all that is pretty clear. It’s more the time and new technology coming into the market, and everyone needs to feel and touch and smell it before they can accept it fully,” he says.

Still, John Hall of the University at Buffalo, New York, thinks the idea of wooden turbines is promising – not least because huge demand for wind turbines in the coming decades is going to put the steel industry under severe pressure. By some predictions, the global wind turbine market is expected to double in value by the end of the decade – steelmaking capacity will struggle to keep up.

The industry may be naturally “risk averse”, he says, but that will quickly change if materials are in short supply. “If [the industry] begins to experience shortages or anything that is going to slow its growth, I think it will be open to innovation,” he says.

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