A Swedish start-up is manufacturing wind turbine towers from wood, reducing CO₂ emissions. Wind energy is a crucial element in the energy system decarbonisation process, but as is well known, wind turbine structures also use materials that generate significant carbon dioxide emissions, such as steel.
Swedish start-up Modvion is drawing on Scandinavian expertise to tackle this problem by installing wooden towers. The world's tallest wooden wind turbine tower was recently unveiled near Gothenburg, in south-west Sweden. The 150-metre-tall structure features a two-megawatt generator, providing enough clean energy to power almost 400 homes.
Is wood a good alternative to using steel in wind turbine towers?
Steel is the most commonly used material for wind turbine towers to date, favoured for its strength and durability. As towers become taller, the logistics of their installation become more complex. The massive metal components are heavy and difficult to transport. Tall steel towers require extra reinforcement. Modvion laminated timber towers are manufactured from modules that are easy to load onto trucks; they do not require reinforcement.
Because wooden towers have a higher strength-to-weight ratio, the structures are lighter and easier to assemble. Components of the wooden towers are also bonded with glue, as opposed to the thousands of bolts required for steel towers, which also need regular inspection. A layer of waterproof paint protects the wooden tower from the effects of the weather.
Modvion points out that (when assessed over time) wooden towers cost less than steel towers. For instance, a major advantage is the greater potential height of wooden towers, and they are also “protected” from steel price fluctuations. So far, Modvion has only installed wooden towers on land. With minor adjustments, they could also be used offshore.
Theoretically, wooden towers could be built up to 1,500 metres tall, while current “demand for height” hovers around 150-200 metres.
How do you compare the emissions of steel versus wooden wind turbine towers?
Data from Modvion shows that a 110-metre-tall steel wind turbine generates approximately 1,250 tonnes of CO₂ over its life cycle. For a wooden tower, emissions are 90% lower – approximately 125 tonnes.
When the wooden towers reach the end of their service life, they can subsequently be used in construction as high-strength beams, both extending the use of the timber and further reducing the impact generated.
“We like to view our towers as a vertical storage of future building materials,” states Modvion. The company estimates that building wind turbine towers from wood reduces the emissions generated by wind power plants by approximately 30% per kWh produced. One tower requires 300-1,200 m³ of timber. Modvion uses spruce grown in Scandinavia from sustainably managed forests, where the volume of forest regrowth exceeds the volume of logging.
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