Wooden wind turbines?

Recently there has been a lot of talk about start-ups that are developing both wooden wind turbine towers and blades. These are still very embryonic companies and projects, but it is worth taking a look at this technology to see what the future holds.

 

LVL or lumber

LVL (Laminated Veneer Lumber) is an industrial product that basically consists of bonding solid wood boards with glue to make very strong boards.

 

 

It was created in the United States in the 1970s as an industrialised building solution.

 

 

It is a material widely used in construction as it offers great advantages over steel and concrete:

• Increased strength
• Lower weight
• High load capacity
• Increased environmental sustainability

 

As far as fire resistance is concerned, despite being wood with adhesive, it does not seem to be a particularly worrying aspect as it complies with all building regulations. Moreover, being an industrial product, it can be configured depending on the use. It is very popular in North America and the Nordic countries, where there are buildings where LVL has largely replaced concrete and steel.

 

 

Stora Enso is the LVL manufacturer behind the wood applications in the wind energy world. It is a Finnish company with 20,000 employees and annual sales of €9.4 billion in 2023, and its wood building materials business unit already accounts for 15% of its turnover. On its website you can see many construction projects made with LVL.

 

Modvion: wooden towers

 

The Swedish company Modvion is undoubtedly the best known in the sector with its laminated timber towers and has attracted the interest of large companies. Vestas entered its capital in 2021 through its venture capital division. Stora Enso is also one of its technology partners (and its LVL supplier), while both Vattenfall and RWE have shown commercial interest but no commitment to buy. In fact, it is striking that Vattenfall announced its interest in 2020 and then there have been no commercial projects with this type of towers.

 

 

Modvion has installed 2 prototype towers: a 30m tower in 2020 and a 105m tower in 2023 with a V90 2 MW on top. This project has had the most repercussion and is very well documented in this video:

 

 

It should be noted that the company’s main selling point is the lower carbon footprint of this solution compared to steel or even concrete. Ease of transport and the possibility of reaching heights of up to 200m are also mentioned as advantages.

 

The company’s goal is very ambitious, as it talks about having 10% of the world share in 10 years. We will see if the cost levels and assembly speed are on a par with tubular towers, because if not, it will be difficult to see them beyond niche projects.

 

Voodin: wooden blades

 

German start-up Voodin Blades is committed to applying LVL material to wind turbine blades. They have already installed the first prototype with 20m blades on an old Enercon 500 kW turbine in Germany.

 

 

They have plans to install 60m and 80m blades in future prototypes. Like Modvion, its technology partner and supplier is Stora Enso.

 

As in the case of the towers, the lower carbon footprint in manufacturing is one of the selling points, but above and beyond that is recyclability. With the technological challenges in recycling fibreglass blades, having wooden blades seems a clear advantage from a circularity point of view.

 

It seems clear that the strength and flexibility of the wood is perfect for the blades but I have not found any information about the weight. I suspect that a 100% LVL blade will be heavier than its fibreglass and/or carbon equivalent. If so it would be a very big limitation as the weight of the rotor sizes the rest of the turbine and more weight spinning would make the rest of the wind turbine much more expensive due to higher loads.

 

Advantages and potential disadvantages of LVL wood

 

We have already seen some of its main advantages:

• Lower carbon footprint: Voodin talks about 78% less CO2 emissions
• Recyclability: especially compared to fibreglass
• Weight: much lighter than steel and concrete. In fact, if we talk about the strength to weight ratio, LVL has a value twice that of steel.
• Modularity: it is a product that is manufactured in a modular way and transported to the field.
• Sustainability: wood from sustainable forests

 

But there are areas where the competitiveness of the solution is unclear:

• Cost: although Voodin talks about a 20% price reduction, it is difficult to validate this until there are commercial projects.
• Assembly times: no details are given for the towers, but on paper, assembly does not appear to be straightforward.
• Weight: for blades this is a key issue and there is no data.

 

Is the use of wood in turbines new?

 

No, wood has been used in industry for a long time. The most widespread use a few years ago was balsa wood for the beam of the blades. The properties of this type of wood in terms of strength and weight made it perfect for the structural part of the blade. Ecuador is the main exporter of balsa wood as explained in this article.

 

A few years ago there was some controversy because the black market in balsa wood was contributing to the deforestation of the Amazon. In fact, the first edition of the always highly recommended WindLetter by Sergio Fdez Munguía talked about this issue

 

Balsa wood has been gradually displaced by composite materials such as PET with similar properties and greater availability.

 

But if we are talking about pioneers in the use of wood, the English company Aerolaminates takes the lead. As early as the mid-1990s, it had already developed the technology to manufacture blades from wood and epoxy fibre. The company was later bought by NEG Micon in 1999, which subsequently merged with Vestas. In a Google search, it seems that the blades made with this technology had some problems with lightning strikes. In this old article from a specialised magazine called AITIM you can find a very interesting description of the manufacture of these blades. It is a pity that it does not include photos.

 

Are there any other components that could be made of wood?

 

Without going into cost considerations, it seems that LVL can be an alternative to steel and concrete. Without having conclusive data, it seems that by weight it is more complicated to replace fibreglass. The casing of the nacelles could be a use but they are currently made of fibreglass (the old Siemens cylindrical ones were made of metal) so it would add weight. Perhaps the tower internals (platforms, ladders, etc) could be made of wood. The rest of the components (castings, mechanical components, electrical, etc) seem unlikely to be made of wood.

 

Conclusion

 

It is undoubtedly a trend to follow in the coming years, especially towers made of this material. I see it as difficult for them to overtake steel towers in terms of cost and speed of assembly, but they could certainly carve out a niche in the market if in the future there are limitations on the carbon footprint of wind farms. They could also compete in very tall towers alongside other mature solutions such as concrete (Max Bogl or Nordex) and innovative solutions such as Nabrawind.