The need to find ways to recycle wind turbine blades is once again in the spotlight, in Europe and in the US, as the number of onshore and offshore windfarms grows and as blades get larger and larger
Earlier this month, WindEurope, the European Chemical Industry Council (Cefic) and the European Composites Industry Association (EuCIA) presented recommendations for recycling wind turbine blades in a new report Accelerating Wind Turbine Blade Circularity.
Weeks earlier, Electric Power Research Institute (EPRI) and the American Composite Manufacturers Association (ACMA) also addressed questions related to recycling turbine blades that would otherwise end up in landfills in a report, Wind Turbine Blade Recycling: Preliminary Assessment.
Today around 85 to 90% of wind turbines’ total mass can be recycled. But turbine blades represent a specific challenge. Made from complex composite materials to allow for lighter and more durable blades, they require specific processes for recycling.
The European report’s key conclusions are that there are existing technologies to recycle wind turbine blades, but these solutions are not yet all available at industrial scale and economically competitive.
Today, the main technology for recycling composite waste is through cement co-processing. WindEurope, Cefic and EuCIA strongly support increasing and improving composite waste recycling through developing alternative recycling technologies, but this requires increased research and innovation funding.
At the same time, existing treatment routes such as cement co-processing must be deployed more widely to deal with the growing waste streams.
WindEurope said the best strategy for wind turbine blades is one that combines design, testing, maintenance, upgrades, and the appropriate recycling technology to ensure the maximum value of the material is retrieved throughout its lifetime. This requires a better understanding of the environmental impacts associated with the choice of materials during design and with the different waste treatment methods at end-of-life.
Finally, composite recycling is a cross-sector challenge. An active engagement from all the composite-using sectors and authorities is required to develop cost-effective solutions and strong European value chains.
Composite materials are being recycled today through cement co-processing, where the mineral components are reused in the cement, and the organic fraction replaces coal as a fuel. Through that process, the CO2 output of the cement manufacturing process can be significantly reduced (up to a 16% reduction is possible if composites represent 75% of cement raw materials). Cement co-processing is commercially available for processing large volumes of waste (albeit not in all geographies).
Apart from recycling through cement co-processing, alternative technologies like mechanical recycling, solvolysis and pyrolysis are being developed, ultimately providing the industry with additional solutions for end-of-life.
The EPRI/ACMA report also provides guidance on R&D priorities, including potential recycling and repurposing solutions, and next steps for research and development.
The commercially available technologies reviewed by the report include blade life extension, pyrolysis, cement kilns applications and grinding turbine blades to re-use them as filler material in a variety of products.
EPRI highlighted that the US hosts one of the largest and fastest-growing wind markets in the world and the overall size of the market is expected to grow rapidly. Using a scenario of wind power supplying 20% national end-use electricity demand by 2030 and 35% by 2050, the US Department of Energy projects total wind generating capacity will reach 224 GW by 2030 and 404 GW by 2050.
Newer installations have all seen significant increases in turbine, rotor size and height over time, increasing average rotor diameter from 50 m in 1998 to over 110 m in 2017. It will grow further as the US offshore wind industry takes off, but disposal becomes more difficult as the blade size increases.
The EPRI/ACMA report said the projected amount of blade waste could vary from about 200,000 tonnes per year (based on a 15-year lifetime) up to about 370,000 tonnes per year (based on a 25-year lifetime) by 2050. The cumulative blade waste through 2050 is estimated at about 4M tonnes.
The report said transportation is a large cost variable and the proximity of central processing and recycling facilities to a high concentration of windfarms and to major transportation networks is important.
Mechanical reprocessing (grinding and use as filler) faces economic and market challenges, including a lack of high-value end-use applications. Cement kilns are more sustainable but currently cost about twice as much as solid waste disposal. Pyrolysis offers more attractive economics for recovery of carbon fibre than for glass fibre, but it requires more technology development and a higher initial investment than the other options, the report said.
Among the primary recommendations for research included in the report are that a rigorous assessment comparing life extension, pyrolysis, cement kilns, and re-grind/re-use, particularly in comparison with solid waste disposal. Others include assessment and development of other emerging technologies and uses, and collaborative development of a commercial-scale facility for front-end processing of composites waste material.
The report said although the technical and economic feasibility of pyrolysis is well established for carbon fibre, applications development of the resulting glass fibre is needed to generate market pull for the recycled glass fibre.
Commercial cement kiln facilities exist in Europe, and a successful pilot project has been carried out in the US using composite boatbuilding material, but no commercial facility yet exists in the US, although one company is seeking funding to start up processing facilities to provide a front-end for the use of composites with cement kilns.
The economic feasibility of re-grind/re-use is not economically feasible according to one source because it is more expensive than solid waste disposal. But another source reported that it was less expensive – and therefore more appealing – than solid waste disposal.
WindEurope said it hoped the EU would prioritise R&I funding to diversify and scale up recycling technologies and to develop new, high-performance materials for blades with enhanced circularity as part of the next R&I framework programme, Horizon Europe. It said that doing so is critical to Europe’s technology leadership as we transition from a linear to a circular economy.
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