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