Assess the composites stock and waste forecast in the European wind-energy sector - Solution

Composite materials stock and expected trends in the wind energy sector

The first scope of this activity is to estimate and characterize with a sufficient level of detail the installed stock and expected trends of wind farms and wind blades, in order to enable an estimation of the upcoming streams of dismantled composites in the next years.

According to ^[1], the cumulative capacity of wind energy plants in Europe reached 235 GW in 2021, 207 GW onshore and 28 GW offshore.

Aggregated data about the availability and expected growth of composite materials stock in the wind energy installations in Europe are not available in literature, therefore, some estimation must be done to derive data of other nature. In this deliverable, two parallel calculations are made and then compared.

Capacity-to–weight single conversion factor

As previously introduced, ^[2] propose a capacity-to–weight conversion factor to match the power of a wind energy installation with the availability of composites inside it. Moreover, market studies as ^[1], ^[3], ^[4] report the cumulated installed European capacity of inshore and offshore windfarms, as well as its expected growth for at least the next five years.

It is therefore possible to simply derive the current and future composites stock in the wind energy plants in Europe exploiting the 1 MW = 12 to 15 tons of composites factor the following equations.

Given the assumptions of:

• New installations forecasts as reported in the conservative scenario of ^[1].
• Yearly decommissioning rate of 0.2% of overall capacity (it was 0.17% in 2021).

The cumulated wind energy capacity installed in Europe in 2021-2026 is reported in Table 3.

Finally, it is possible to derive the availability of composites populating these wind farms as reported in Table 4.

The simplicity of this method implies that its robustness is dramatically dependent on the quality and reliability of the conversion factor exploited in the capacity-weight conversion. Since available literature lacks of sources to confirm and better contextualize this data, in this deliverable, an alternative calculation method is proposed to confirm and balance the obtained data.

Turbines population composites weight estimation

To propose an alternative to the single conversion factor method, in this section, another calculation method is proposed: a cascade calculation to estimate the number of turbines available in Europe, their weighted average dimensions and finally the quantity of composites available. This is also the calculation proposed as the activity exercise.

The calculation of the number and dimension of turbines installed in Europe is based on the following data:

• The total number of European offshore wind turbines is known and available in ^[3] for 2020.
• The number of new turbines installed in Europe is known for the years 2020 and 2021 ^[1], ^[4].
• The numbers of turbines installed in the last decades can be estimated by comparing the installed capacity within the years and the average capacity of turbines of different periods ^[2].
• The dimension, and weight of wind blades loaded in turbines of different generations and capacity is estimated according to ^[5].
• Composite materials (fiber and resin) account for 92% of the overall blade weight. This percentage remains valid for turbines of different generations and dimensions ^[5].
• Three blades per turbine are considered for all turbines.

Conservative data are always preferred in case of conflict.

Data are summarized in Table 5 and Table 6.

Finally, it is possible to estimate the weight of composite available in the European wind turbines stock by populating the following equation.

$\begin{aligned} \text{Composites}_{\text{stock}}\,[\text{kton}] ={}& \text{N. of turbines}_{\text{stock}} \\ &\times 3\,\frac{\text{blades}}{\text{turbine}} \\ &\times \text{Avg. weight} \\ &\times 0.92\,\frac{\%\text{ composites}}{\text{Tot. weight}} \\ &\times 10^{-3}\,\frac{\text{kton}}{\text{ton}} \end{aligned}$

Results of this calculation are reported in Table 7.

Results comparison

It is possible to appreciate how the estimations of the stock of composite materials in the European wind energy market made with the two approaches doesn’t create conflict, as the “turbines population” estimation remains between the low and high “single conversion factor” ones.

Forecast of wind energy composite waste volumes in Europe

Data presented in the previous sections of this activity are here merged, integrated and used to generate a forecast of the expected wind energy composite waste volumes for the period 2023 – 2040.

Manufacturing waste

The first waste stream analyzed in this section is the manufacturing waste. To forecast the manufacturing waste volumes expected for 2023 – 2040, calculations are based on these assumptions:

• Since manufacturing waste is based on turbines production and not on turbines installation, this computation considers the yearly European wind turbines production, and not wind energy local installation.
• The yearly European wind turbines production is calculated by multiplying the yearly global wind energy systems demand with the European production market share percentage.
• The yearly global wind energy systems demand is taken from ^[6], conservative scenario, for the 2023 – 2030 period, and then maintained at constant 2% growth for the 2030 – 2040 period.
• European production market share is set to 39% ^[7], maintained constant for the whole forecast. Major European wind turbines manufacturers: Vestas, Siemens Gamesa, Nordex Acciona.
• Wastes generated during the manufacturing phase of commercial wind blades manufacturing processes is estimated starting from ^[8], with low value (12%). Neither in this or other publications available in literature, there is evidence about the nature of this waste stream (consumables, shrinkages, etc.). In this deliverable, a conservative approach sets the actual composites waste rate as 5% of the overall composites mass of the blade.

The first step to forecast the expected European manufacturing waste is therefore to estimate the European market size of new wind energy systems manufacturing. Results or this computation are represented in Figure 19.

Finally, it is possible to derive the estimated volumes of manufacturing waste by:

• Converting the expected total capacity of wind energy systems manufactured in Europe in equivalent weight of composites embedded in wind turbines by using the capacity-to – weight single conversion factors proposed by ^[2].
• Deriving the quantity of associated production wastes.

End-of-life wind energy systems

To estimate the European return volumes of end-of-life wind energy systems, data related to the current composites stock presented in the previous sections must be enriched with a more granular identification of yearly installed wind energy capacity through the years.

Since the end-of-life blades forecast starts from the tracking of yearly installed new systems in the last decades, the already cited sources are enforced by auxiliary ones ^[9], to achieve a yearly based definition of the installed capacity in Europe for the 2000 – 2022 period.

Finally, it is possible to forecast the expected return of decommissioned wind blades. Once again, equivalent weight of composites embedded in wind turbines is calculated by applying the capacity-to – weight single conversion factors proposed by ^[2].

To derive the volumes of decommissioned wind turbines, this activity considers two decommissioning possibilities for wind blades:

• Wind blades can be decommissioned before their natural end-of-life because of failure or turbine repowering. It is estimated that 3% of wind blades are decommissioned before their natural end-of-life.
• Wind blades can be decommissioned reaching their natural end-of-life. Typical wind blades lifecycle is 20-25 years ^[8].

Considering this double possibility, the wind blades yearly decommissioning profile is calculated as follows:

• Early decommissioning of blades is modelled with constant flat rate for the 20 years natural lifecycle. The 3% of wind blades marketized in year y are decommissioned within y+1 and y+20, same quantity each year.
• Those blades which don’t undergo early decommissioning are dismantled at their natural end-of-life with constant flat rate (same quantity each year) between 21^st lifecycle year and 25^th lifecycle year.

Forecasts about the volumes of composite waste coming from decommissioned inshore and offshore wind turbines are finally visible in Figure 22 and Figure 23.

Waste streams comparison

To complete the forecasting analysis, Figure 24 compares and cumulates the three above presented waste streams, namely production waste, end-of-life inshore turbines and end-of-life offshore turbines (1 MW = 12 ton scenario). Considerations can be made on this recapitulatory graph:

• Composites wastes from the wind energy sector represent a concrete European circular economy challenge. Yearly return volumes in the next decades will reach more than 200 kton, summing up the manufacturing waste and dismantled turbines streams.
• Inshore end-of-life turbines represent the main composites waste channel, both present and in the future.
• Offshore turbines installation volumes rose to GW magnitudes only in the last decade. Therefore, their related returning volumes are not expected to growth significantly before 2030. Nevertheless, difficulties in offshore wind farms decommissioning already represent a technical challenge for specialized dismantling companies.
• Manufacturing waste volumes are expected to remain rather constant over the years, following the gradual expected market growth. Nevertheless, their management is fundamental to guarantee complete circular management of composites in the wind energy sector.