Wind turbine towers are for the most part made of steel, which means the larger the wind turbine, the more steel used in the construction of turbine tower, and the larger the tower needed to support the turbine. Transporting these towers, which are hundreds of meters long, from manufacturing sites to wind farms for on-site assembly is no easy feat. A Swedish company is attempting to change all that by making turbine towers out of wood as opposed to steel. These towers are significantly lighter than conventional steel towers, although they retain the same looks; the company hopes to bring their new towers to market by 2022.
Sweden-based engineering and industrial design firm Modvion erected a 30-meter tall turbine tower on the outskirts of Gothenburg as a proof of concept. The tower is constructed layer by layer with modular pieces of laminated wood, in much the same way as a 3D jigsaw puzzle. This method of construction has the benefit of allowing the final product to be shipped piecemeal and assembled on-site, as opposed to transporting the entire tower at once.
Ease of transportation confers a major benefit to the viability of these towers, since shippers must abide by traffic safety regulations, which differ by country and specify limits to the dimension of goods shipped. Taiwanese laws, for instance, state that land freights cannot exceed four meters in height (measured from the ground up, including the vehicle itself) if transported by large vehicles and 2.85 meters if transported by small vehicles. Shippers need to apply for a special permit if their freight exceeds said height limit. Given that similar laws exist elsewhere in the world, transporting turbine towers, which are up to 100 meters long and more than 4.3 meters in base diameter, in Europe and North America, where the towers are predominantly used, represents a challenge posed by the regions’ respective traffic safety regulations as well.
Making turbine towers out of wood and with a modular design is certainly one way to overcome this challenge. According to Modvion, not only are their wooden towers modular and light, but the wooden material used also means a lower construction cost while allowing taller towers to be built and accommodating larger turbines, which in turn generate more electricity. Prior research by the U.S. Department of Energy indicates that turbine towers that are 140 meters tall can house turbines that generate up to three times as much electricity as 80-meter tall towers can accommodate.
In addition to advantages like increased electricity generation and ease of transport, Modvion also claims that the manufacturing process of its wooden towers is much more environmentally friendly relative to that of conventional towers. This makes sense, seeing as how steel manufacturing tops the list of carbon emissions from industrial activities. Steel manufacturing requires extreme heat and produces a host of hazardous wastes and pollutants. However, despite having the same amount of environmental impact, making turbine towers of wood is much more carbon neutral than doing so with steel. Case in point, trees planted in the process of producing lumber required for the towers absorb carbon dioxide, which can somewhat offset the carbon dioxide produced as part of the manufacturing and transportation process of the final product. In terms of safety, Modvion claims that wood is just as structurally sound as steel.
Modvion CEO Otto Lundman states that its wooden modules are more durable than steel of equal weight. The team has adopted a modular design for the towers, which are, again, carbon neutral, to allow for room for expansion. Modvion’s design can theoretically yield towers upwards of 120 meters tall. Johan Åhlén, CEO of Modvion’s ODM Moelven Töreboda, indicates that the company can currently manufacture the towers with recycled wood. The towers will generate renewable energy after they become operational.
If Modvion’s trial runs prove successful, the company is expected to start manufacturing its wooden turbine towers for commercial use in 2022, with clients including Varberg Energi, which commissioned a 110-meter tall tower, and Rabbalshede Kraft, which also placed an order for 10 150-meter tall towers.