As wind energy grows in popularity, wind turbines are rapidly being installed across the globe for both on land and offshore. Concern for climate change and declining prices have made wind power an appealing choice for meeting the world’s electricity needs.
However, given the scale of wind energy deployment, it is critical to consider the sustainability of the industry as a whole, and what happens to wind turbines when wind developers decommission them.
The blades on wind turbines are of particular concern.
Wind turbine blades are recyclable, although it rarely happens across much of Europe and North America. Recycling blades has not yet been implemented on a large scale. Unfortunately, this means many turbine blades end up in landfills, or are incinerated because recycling efforts are expensive.
Yet, renewable energy companies are under growing pressure to be more sustainable during the manufacturing and decommissioning phases.
Despite progress in this area, considerable work is needed to mitigate this growing source of waste worldwide. Economically sound and technologically viable solutions are essential to reduce wind farm waste.
“If you are talking about a sustainable, renewable fuel source, it’s not appropriate to then pollute the environment with materials that are decommissioned,” said Larry Bank, a research faculty member at the Georgia Institute of Technology.
Bank is part of the Re-wind team, a collaboration between researchers in the US, Ireland, and Northern Ireland studying repurposing wind turbine blades for civil engineering projects.
What are wind turbines blades made of?
Turbine blades are made of fibreglass and composite materials containing thermoset resin. Unfortunately, blades are tough to recycle because of the materials they contain.
Typically, the recycling options involve down-cycling the material into low-value products instead of recycling them into products of the same or greater value.
That latter is necessary to make truly sustainable, economically-viable products, closing the recycling loop.
Yes, there are numerous examples of successful recycling initiatives to make building materials. For example, global Fiberglass Solutions Inc., a US-based startup, recycles fibreglass waste to make roadway materials, railroad ties, and building materials.
The process entails grinding up recyclable material into a feedstock for new products.
GE Renewable Energy is working on making Portland cement from decommissioned wind turbine blades in the U.S. and Europe. The process entails grinding up materials for cement and recovering organic materials to provide energy for the manufacturing process for the cement.
According to GE, manufacturing cement this way can reduce carbon dioxide emissions by 20% compared to conventional approaches, but this approach comes at a higher cost.
Jérôme Pécresse, CEO of GE Renewable Energy said, “This is a truly exciting next step in our journey to introduce new circular lifecycle improvements for the wind industry.”
Although this is undoubtedly a step in the right direction, these initiatives involves grinding down the blade material and downcycling it, producing lower value goods. This approach can increase expenses when decommissioning wind farms.
Unfortunately, the resin used to make most wind turbine blades makes it extremely difficult to melt the blades down and make high-value products from the material.
Yet, to achieve a circular economy, wind turbine blades need to be converted into materials with roughly equal or even greater value to achieve a circular economy.
Another strategy is finding new creative uses for turbine blades without shredding down the materials.
Because the blades are so durable, it makes them an attractive option, especially in areas prone to extreme weather and natural disasters.
There are successful examples of repurposing decommission turbine blades for playgrounds in the Netherlands, bike shelters in Denmark, and pedestrian bridges in Ireland. Other possibilities include cell phone towers and fencing.
Re-wind is collaborating with an electric utility company to research “blade poles,” making high-transmission electrical transmission towers from decommissioned turbine blades. Engineers want to study this approach to ensure it is safe before installing live wires.
According to Bank, the Re-wind team is also exploring using turbine blades for affordable housing. “One of the first things we looked at was cutting up these blades into pieces that could be given for free or for very low cost to individuals in economically deprived neighborhoods that could be using them for construction.”
Although it can be difficult to implement on a large scale, repurposing has many advantages. Unlike recycling, which can be an energy-intensive process, repurposing bypasses the need to extensively process materials.
To understand the scale of the waste from wind turbine blades, it is helpful to consider their size.
The hub height and rotor diameter have grown significantly in the last 25 years for utility-scale wind farms, increasing their nameplate capacity.
According to the Electric Power Research Institute, blade size has increased from an average diameter of 145 feet in 1997 to 367 feet in 2017.
There is currently a race among wind turbine manufacturers to make the biggest wind turbines with the greatest capacity to meet the renewable energy needs of more homes and businesses.
The longest turbine blades are 108 meters (354 feet) for Siemens Gamesa’s SG 14-222 DD prototype offshore wind turbine. The turbines at 15 MW capacity with Power Boost, enough to power 18,000 households annually.
However, such large turbines and blades present transportation issues and recycling challenges. This means that recycling initiatives in 20 years will need to be able to handle such long turbine blades.
There is currently no ban on wind turbine blades going to landfills in the U.S. or across Europe, but several countries have them. Unfortunately, turbine blades are slow to break down in landfills and take up a lot of space. However, WindEurope has called for a Europe-wide ban on decommissioned blades from wind energy projects by 2025.
“Wind energy is a green technology,” said Giles Dickson, WindEurope CEO. “Sustainability is part of our DNA. That’s why we are constantly striving to further reduce our impact on the environment. A ban on landfilling wind turbine blades will help accelerate the development of sustainable recycling technologies. Austria, Finland, Germany, and the Netherlands already have a landfill ban in place. But we call upon the European Commission to propose a harmonised European approach.”
In the absence of a ban, Vattenfall, a Swedish multinational power company, has set ambitious targets for 2025 and 2030 to tackle wind turbine blade waste in Europe.
“It is no longer acceptable for composite waste from the wind industry to be placed in landfills, even though specific country legislation allows for this,” said Eva Philipp, Head of Environment and Sustainability Busines Area Wind. “Achieving 50 per cent recycling by 2025 and 100 per cent by 2030 is a big challenge. Solutions to tackle this challenge do not exist in large scale today, so significant efforts are needed to reach this long-term goal. Therefore we will engage in and provide blades to research initiatives that will foster further technology innovation and testing of more advanced recycling technologies.”
The turbine blades are one of the most difficult components of a wind turbine to recycle, and other components are more readily recyclable.
Wind turbine towers, generators, and gearboxes are largely comprised of steel and copper, which are relatively easy to recycle. There is a strong market for these materials and recycling infrastructure in place to process them.
As the world races to reduce greenhouse gas emissions, there has been a lot of emphasis on the operation of wind turbines but much less on the decommissioning of these projects.
Although other components of wind turbines, such as the tower, gearbox, and generator, are relatively easy to recycle, the turbine blades are not, making it an important issue to address.
“They are very difficult to move around, and they are not biodegradable,” Bank said. “It’s like a big, hollow tube that takes up a tremendous amount of space.”
In addition, future restrictions on disposing of turbine blades are likely. As a result, wind farm developers need available solutions and infrastructure in place.
Similarly, the solar energy industry is struggling to make truly recyclable solar panels and create the infrastructure to process this growing waste stream.
If not properly addressed, recyclability issues mean that virgin materials are used to make new products instead of completing the recycling loop. Also, waste management issues could give the renewable energy industry a bad name, despite its significant accomplishments.
Researchers are making progress towards more recyclable wind turbine blades. Currently, blades are made from thermoset resin, which requires a lot of energy in the manufacturing process and is problematic to recycle.
However, at the National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy, researchers have created a wind turbine blade from thermoplastic resin that is low-cost, lightweight, and seems to be more recyclable.
“With thermoset resin systems, it’s almost like when you fry an egg. You can’t reverse that,” said Derek Berry, a senior engineer at NREL in a press release. “But with a thermoplastic resin system, you can make a blade out of it. You heat it to a certain temperature, and it melts back down. You can get the liquid resin back and reuse that.”
The test blades show many advantages from a recyclability standpoint. “The typical thermoset materials don’t melt down,” said Derek Berry, a senior wind technology engineer at the National Renewable Energy Laboratory. “Therefore, our options for recycling are limited, less cost effective, and produce recycled material that is less useful in terms of material properties.”
Therefore, if these research blades turn out to be durable, this could be a game-changer for the wind turbine manufacturing industry because they present several other advantages. The test blades are lightweight, making them more economical to ship.
However, researchers think it might be possible for manufacturers to make turbine blades onsite, potentially alleviating some transportation issues.
Also, the blades from thermoplastic resin require less energy during the manufacturing process because they cure at room temperature, lowering energy and labour costs while reducing greenhouse gas emissions.
As a result, researchers estimate the new turbines could be 5% less expensive to manufacture. The lower the cost of wind energy, the greater the opportunities for large-scale deployment.
So far, the research looks promising for turbine performance. “The thermoplastic material absorbs more energy from loads on the blades due to the wind, which can reduce the wear and tear from these loads to the rest of the turbine system, which is a good thing,” said NREL researcher Robynne Murray.
Despite being promising, the potential end-of-life benefits from making turbine blades with thermoplastic resins are still decades away. Even if all blades were made from this material moving forward, these wind farms wouldn’t be decommissioned for at least a couple of decades.
Although blade recyclability may not have been a top concern for wind energy companies a couple of decades ago, this is changing, according to Berry. “Today, recyclability is something that is near the top of the list of concerns. All of these companies are saying, ‘We need to change what we’re doing, number one because it’s the right thing to do, number two because regulations might be coming down the road. Number three, because we’re a green industry and we want to remain a green industry.’”
To implement large-scale solutions, a variety of stakeholders must come together. For example, researchers are developing truly recyclable materials, wind turbine manufacturers are collaborating with recycling partners, and communities are looking for ways to repurpose turbine blades.