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.

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.

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