Closing the circle
In ‘Gone with the wind?’ (issue one, 2026), Chris Stokel-Walker rightly says it is difficult and costly to separate the fibres from the resin matrix in composite wind turbine blades; we knew this decades ago. The fibre-matrix system is designed to be durable and is not supposed to fall apart. To attempt a solution for recycling fibrous composites, I developed a novel method for retaining the chemical feedstock (fibres and resin) and remanufacturing composite components, which remained over 50% of the original E modulus, tensile strength and interlaminar shear strength.
With teams of final-year
project students at the University of Bristol, I investigated the feasibility of the process. The method consisted of splitting (delaminating) the composite
and then crushing it at intervals
to create a semi-flexible mat. The mat was used to remanufacture tubes from previously flattish material by laying over a former and impregnating with a laminating resin. Flat plates were made from previously curved material by laying up as before and consolidating in a hot press.
I presented our findings at several composites and recycling conferences, and a paper was written that covers most of what we did (Adams et al, Applied Composite Materials (2014) 21:263-284). Designing and making composite structures
is exciting and makes money,
but few think of the end-of-life scenario. Our method shows that it is not necessary to crush into powder and use as a filler, or
to burn or put into landfill, but
it is possible to remanufacture composite components. If we could get good results using undergraduates and a university workshop, surely industry could use these ideas to solve the problem of recycling large composite structures and
close the circle.
Professor R D Adams, Oxford, FIMechE, CEng
Blowing in the wind
Perhaps we are looking at the problem of recycling wind turbine blades from the wrong wind direction. Instead of making/designing the blades to have
a longer life, perhaps with
even more difficult-to-recycle materials, could the blades be made to have a shorter life with cheaper, more easily recycled materials? Yes, there is of course a cost to replace the blades and
I have no idea what this is or if a replacement would be financially viable. Maybe we should just dump the blades in the sea to create artificial reefs to grow
our fish stocks (so European fishermen can benefit).
In general, too little thought is put into what happens when a product is designed, brought to market, used and discarded, and the associated costs of recycling/decommissioning, whether it is
a short-term item such as plastic bottles or one-time vapes, or long-term such as wind turbine blades, solar panels, etc (let
alone nuclear waste), before it
gets into the market.
Most plastic bottles are recyclable, I hear you say, but
how many actually are? Perhaps a return to the old system of having to pay a refundable deposit on
an item should be reintroduced. By giving something a value it should reduce waste and pollution through better collection and thus, hopefully, recycling. (The same payment of a deposit might be applied to NHS appointments, of which some 15 million a year are missed at a cost of around £30 a pop, but I digress.)
While kids are not going to collect wind turbine blades to supplement their pocket money, requiring wind turbine, solar farm or similar owners/operators to set aside funds in escrow to recycle/clear up upon decommissioning might focus minds, and not just push the problem and cost on
to the next generation when the owners of such equipment/facilities decide to conveniently go out of business, having
reaped 25 years of profit.
J Lander, MIMechE
Remote possibility
FT Murphy’s idea to install remote-controlled switches in a house wiring (‘Your voice’, issue one, 2026) has a difficult hurdle
to overcome. When a new circuit is installed, it is tested to ensure continuity in the fixed wiring and that its resistance to earth is high enough to switch the power on.
In theory, any alteration to the circuit and a further test is required. Sockets with USB charger sockets have become quite popular. These have to be shorted out during a high-voltage test so the sockets and their wiring are not actually tested. Switches would fall into the same category. So we do not know
if the socket or switch has been correctly connected after the
test. I suggest it is far better for you to take the exercise and operate the switch manually.
Mike Travers, Fife
Want to learn more about product lifecycles? Learn how to meet customer requirements for quality, cost and lead time at an IMechE training course, with topics including additive manufacturing, sustainability and value engineering. Find out more on the Product Lifecycle page.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.