How to recycle composites? That has been a question rattling around in the brains of engineers for decades. Thankfully, the composites industry has been making impressive strides in recent years. Now there’s a plan in the European Union (EU) to turn aging turbine blades into cement. The plan is an interesting one if nothing else.
As wonderful as composite materials like glass carbon fiber are, working with them produces a tremendous amount of waste. Moreover, there isn’t much use for that waste. Yet discarding the waste in a landfill isn’t a very good option either. So a lot of bright minds have been working on ways to effectively reduce it via recycling.
A big thing in carbon fiber right now is to chop up waste and use it to create parts that don’t require the structural integrity of virgin carbon fiber. Salt Lake City’s Rock West Composites says that the technologies for utilizing chopped carbon fiber waste have improved significantly in recent years. More and more recycled parts are showing up in sporting goods, auto manufacturing, and so forth. However, turning waste into cement is something entirely different.
Only Glass Fiber for Now
According to Composites World senior editor Scott Francis, the EU plan to turn turbine blades into cement is limited just to glass fiber composites – at least for now. A consortium of organizations have already come up with a comprehensive recycling plan that should be ready to implement any time now. Meanwhile, engineers will be looking at ways to use carbon fiber waste in a similar fashion.
According to Francis, the EU is home to some 130,000 wind turbines. Approximately 12,000 of those turbines are expected to be decommissioned within the next five years due to their age. When that happens, the EU’s renewable energy sector will be sitting on tons of old glass fiber blades they have no use for.
The plan is to chop the blades on site before shipping them to a recycling plant. There, two things will happen. First, the waste will be burned in order to separate the glass fibers from the resin in which they are embedded. Project planners believe they can generate electricity and reduce the need for coal at the same time.
Once the resin has been burned away, the resulting fibers will be used to replace some of the silica needed for cement production. Planners say that this will reduce the energy required to create cement without compromising structural integrity.
Adapting the Plan for Carbon Fiber
Francis was not clear in his article about why the process only works for glass-reinforced composites. Having said that, he did make mention the fact that engineers are also working on mechanical recycling, solvolysis and pyrolysis. These three processes are more adaptable to carbon fiber.
Mechanical recycling is the chopping and grinding that already proliferates the industry. The other two are chemical recycling processes that use different solvents to separate carbon fiber from epoxy resin. If an effective chemical recycling process can be developed, perhaps carbon fibers can be retrieved in volumes great enough to use them for other purposes.
Who knows? The cement that road crews are pouring five years from now might be partially made from recycled wind turbine blades. What was once turning above the heads of drivers may one day be passing under the wheels of their cars. It’s ironic, isn’t it?
It’s all in an effort to reduce composite waste. Reduce that waste and it’s also possible to reduce the energy consumption required to create composite materials. That is good all the way around.