Wind turbines: can we make blades recyclable? 

The wind pow­er indus­try is fac­ing a major turn­ing point. The fleet is aging. In Den­mark, 50% of wind tur­bines are over 15 years old, and 40% in Ger­many¹. Although wind tur­bines are designed to last about 20 years, the age of renew­al in Europe varies from 9 to 27 years. In France, only a small part (less than 5%) of the installed capac­i­ty is old­er than 15 years, and Ademe points out that most renewals could take place between 15 and 20 years. In the com­ing years, the poten­tial for renew­al will even accel­er­ate in Europe: it could increase from 3 GW per year in 2020 to more than 6 GW in 2030 accord­ing to Windeu­rope².

So a new ques­tion aris­es: how do we man­age the waste from dis­man­tled wind farms? Accord­ing to DREAL Grand Est³, 90% of wind tur­bines are made of con­crete (840 tons on aver­age) and steel (246 tons). These mate­ri­als are eas­i­ly recy­cled and have sig­nif­i­cant mar­kets. Oth­er mate­ri­als such as cast iron and cop­per are also recy­cled. The sec­ond-hand mar­ket is also well devel­oped and includes major Euro­pean play­ers. « More than 90% of the mass of a wind tur­bine can already be recy­cled in France, these mar­kets are well struc­tured and will be able to absorb larg­er vol­umes, » says Aman­dine Volard, a renew­able ener­gy engi­neer at Ademe.

More than 90 per­cent of the mate­r­i­al from a wind tur­bine can already be recy­cled in France.

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Only the blades pose a prob­lem today. They are made of a com­pos­ite mate­r­i­al: a mix­ture of poly­mer matrix (epoxy resin, polyurethane, or poly­ester) and rein­forc­ing fibres (most­ly glass or car­bon for off­shore wind tur­bines). The ide­al? Recov­er­ing each of the mate­ri­als to reuse them. How­ev­er, « it is very com­pli­cat­ed to sep­a­rate the matrix and the rein­forc­ing fibres, » explains Céline Largeau, head of the Zebra project at IRT Jules Verne. There are sev­er­al sep­a­ra­tion meth­ods: pyrol­y­sis (ther­mal), solvol­y­sis (chem­i­cal), gasi­fi­ca­tion and grinding.

These process­es allow the recov­ery of the fibres and/or the matrix, how­ev­er, no effi­cient recy­cling process is in place today⁴. Some process­es are ful­ly devel­oped and used on an indus­tri­al scale, such as pyrol­y­sis and grind­ing, but they strong­ly degrade the phys­i­cal prop­er­ties of the glass fibres. The recov­ered fibres are more expen­sive and of low­er qual­i­ty than non-recy­cled fibres, and the process is not eco­nom­i­cal­ly viable. Solvol­y­sis, on the oth­er hand, allows the recov­ery of undam­aged glass fibres and a reusable resin.

10,000 to 15,000 tons of com­pos­ites from the wind ener­gy sec­tor will need to be processed each year from 2028 in France.

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But the process is not effi­cient, requires large quan­ti­ties of resources – sol­vent, water, ener­gy – and has not yet been suf­fi­cient­ly devel­oped. As a result, to date, only the incin­er­a­tion of blades in cement plants has been devel­oped, for exam­ple in Ger­many, where the renew­al of wind farms is already sig­nif­i­cant⁵. The com­pos­ite is used as fuel and the residues are incor­po­rat­ed into clinck­er, a con­stituent of cement. We esti­mate that 10,000 to 15,000 tons of com­pos­ites from the wind pow­er sec­tor will need to be processed each year in France from 2028 onwards⁶, » explains Aman­dine Volard. But the cement indus­try is already in demand in sec­tors oth­er than wind pow­er and will not be able to process such quan­ti­ties on its own.

Dri­ven by a num­ber of fac­tors (see box), the indus­try is devel­op­ing new ways of recov­er­ing old blades. Some sep­a­ra­tion process­es that are not yet ful­ly devel­oped – solvol­y­sis, gasi­fi­ca­tion and high-volt­age frag­men­ta­tion – are being test­ed. Mature process­es such as pyrol­y­sis are being improved in order to obtain out­put fibres with inter­est­ing prop­er­ties. The R3FIBRE project⁷, led by Bcir­cu­lar, for exam­ple, makes it pos­si­ble to inte­grate recy­cled fibres into com­mer­cial cement to improve its per­for­mance. Oth­er ini­tia­tives focus on the val­ue chain. “One of the objec­tives of the Zebra project is to iden­ti­fy new sec­tors that could use fibres from wind tur­bines,” explains Céline Largeau. “The auto­mo­tive indus­try, for exam­ple, is a prime sec­tor.” Reuse is anoth­er pos­si­bil­i­ty. In its analy­sis⁸, Bax & Com­pa­ny points out: « For the moment, recy­cling is get­ting the most atten­tion, even if it is not the most desir­able waste man­age­ment strat­e­gy. » Indeed, the authors point to the pos­si­bil­i­ty of direct­ly reusing the blades for exam­ple for build­ing facades. 

Anoth­er key area of action is the devel­op­ment of inno­v­a­tive, ful­ly recy­clable blades. Zero waste has been invit­ed to the table by man­u­fac­tur­ers who are aim­ing for this goal by 2040⁹. Siemens Game­sa has already been mar­ket­ing the first ful­ly recy­clable wind tur­bine blade, the Recy­clable­Blade, since 2021. Com­posed of a new resin and glass fibre, the com­pos­ite mate­r­i­al can be sep­a­rat­ed at the end of its life by chem­i­cal means. In France, the ZEBRA project led by the IRT Jules Verne is focus­ing on anoth­er inno­v­a­tive resin for the sec­tor, ther­mo­plas­tic resin. Com­bined with a high-per­for­mance glass fibre, the result­ing com­pos­ite mate­r­i­al can be chem­i­cal­ly recy­cled. « The glass fibre devel­oped by Owens Corn­ing can incor­po­rate a cer­tain amount of recy­cled glass fibre, which means that this resource can be reused, » says Céline Largeau. The resin can also be reused. One of the chal­lenges of these new blades is to char­ac­ter­ize their car­bon foot­print over their entire life cycle (LCA), because this has nev­er been done before, » says Largeau. We will soon be able to pro­vide the LCA of the Zebra blade, and the results look promising. »

Anaïs Marechal