Recycling Wind Turbine Blades, From Cement to New Blades

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Major wind turbine OEMs are giving serious thoughts to making wind power generation even more sustainable. The need for this became evident when the turbines of the first-ever large wind farms commissioned almost 20 years ago came close to the end of their life cycle.

On the one hand, wind farms use completely renewable or green wind energy to produce electric power. On the other hand, each wind turbine, which has enormous dimensions, consists not only of steel, but also composites that are difficult to recycle. Compounding the problem is technology development, which requires regular replacement of aging equipment with newer and more powerful ones.

This order of things naturally runs counter to the ideas of reducing the carbon footprint, waste-free production and a closed-loop economy, which is why two world’s major wind turbines manufacturers – Vestas (a member of the RAWI) and Siemens Gamesa (a member of the RAWI) – already included the solution to this problem in their own sustainable development strategies.

Vestas and Siemens Gamesa plan to make wind turbines 100% recyclable by 2040, and to bring fully recyclable blades to the market by 2030.

During one of RAWI’s webinars for its members aired this summer, head of Advanced Structures and Sustainability, Vestas Innovation and Concepts Allan K. Poulsen detailed the current options for recycling wind turbines and how Vestas is working to achieve complete processing on an industrial scale.

Recycling a decommissioned wind turbine is a complicated process, to begin with, because it consists of about whopping 25,000 parts. Vestas started building its strategy in this direction by assessing the current situation, which showed that today the company recycles only 26% of the mass of a wind turbine. Nevertheless, with the help of existing technologies it is possible to recycle from 85 to 90% of the mass of s wind turbine. The remaining 10-15% is mainly accounted for by the huge, but at the same time light and strong blades, which are made of thermosetting composite epoxy materials. Composites define these properties, but due to them, blades are also extremely difficult to recycle.

Globally, wind turbines currently use approximately 2.5 million tonnes of composite materials. To make it clear right away, wind energy produces much less composite waste compared to other industries, namely construction, electronics, automobile manufacturing and shipbuilding. Nevertheless, it is important for the wind energy industry as a representative of the sustainable cluster to ensure the availability of sustainable solutions for the processing of all materials used in wind turbines, and given the explosive development of the industry, this responsibility is becoming more and more justified.

Vestas decided to focus on, first, making the blades more recyclable, and second, making them easily recyclable. The existing blade recycling technology is far from perfect as it is extremely energy-intensive and involves the subsequent dumpling of part of the waste. Since Vestas Sustainability Strategy requires a complete rejection of incineration and landfilling, the recycling technology must be improved. In addition, it is important for the closed-loop economy that the recycling of the blades can produce materials for further production of blades once again.

To cope with the task, Vestas became involved in several partnership projects, one of which is DecomBlades, which aims to develop affordable, cost-effective and environmentally friendly solutions for recycling wind turbine blades. This initiative is supported in Denmark at the national level and has received funding through the Danish Innovation Fund Grand Solutions programme. Like Vestas, the participating companies operate globally and have the ability to implement solutions on a global scale that will help the wind energy industry transition to a closed-loop economy.

The search for a blade recycling solution proved so important to wind turbine manufacturers that DecomBlades brought together direct competitors Vestas, Siemens Gamesa, LM Wind Power, and Ørsted A/S, the world’s largest owner and developer of offshore wind farms.

Combination between the competitors for a common goal was supported by leading-edge processing companies, for example, MAKEEN Power, also participating in DecomBlades, is leading the work on pyrolysis technology. Among its tasks is the development and implementation of a pilot project for a pyrolysis unit for processing composite materials.

HJHansen Recycling has taken it upon itself to improve crushing composite technology for easy transport for recycling, as well as to explore the market for the use of crushed blades in new products. FLSmidth is investigating the use of shredded composites and pyrolysis products in the cement production process.

Academics also take part in DecomBlades. The University of Southern Denmark (SDU) is assessing the environmental and economic performance of various supply chains in terms of optimal processing of composite materials. The Technical University of Denmark (DTU) is evaluating the properties of recycled glass fibers and exploring ways to improve the quality of pyrolysis fibers. The possibilities of technical solutions found during the DecomBlades project will later be analyzed and combined by the Energy Cluster Denmark (ECD).

The DecomBlades project will last three years, and the solutions found during its work will make it possible to recycle wind turbine blades completely, without incineration or landfill, which in itself is extremely important. However, they do not allow for the more ambitious goal of zero-waste production of blades from recycled ones.

For this, or rather to create a circular economy in the wind energy sector, Vestas, in collaboration with industry and scientific experts, is working on another project, Circular Economy for Thermosets Epoxy Composites (CETEC). The alliance’s goal is within three years, to provide an industrial blade recycling solution with no loss of quality.

CETEC’s innovative technology involves a two-step processing process. The blade composites are first separated into fiber and epoxy resin. Then, using chemical processes, the resins are separated into simpler components. The method allows glass fibers and epoxy resins to be reused without loss of quality to produce new blades. The cycle is thus closed.

Once CETEC’s blade recycling technology is fully matured and put into production, it will open up new perspectives in composites recycling for industries other than wind energy, where alternative recycling technologies such as solvolysis and pyrolysis have not yet been commercialised.

Vestas, maximising the use of currently available blade recycling technologies and actively participating in the development of new ones required for the closed-loop economy, predicts that within the next 7-20 years blade recycling will become less energy intensive, and the demand for the materials obtained during recycling will increase. In addition, wind turbines themselves will change with their designs becoming easier to disassemble and recycle, which will bring the company much closer to creating a closed-loop economy.

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