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Time to standardise?
Photo courtesy of GE Renewable Energy.
The Haliade-X prototype has a capacity of 14MW and is ready for commercialisation. The rapid growth in the size of offshore WTGs is expected to slow down in the coming years.
The question how far the industry can push this increase in capacity of wind turbines is unknown. Although the electricity production of the turbines is increasing, the costs of the turbine, the blades, the tower, and the costs of transport and installation are also increasing. It is conceivable that at a certain point the additional returns from the increase in capacity do not outweigh the additional costs in the entire value chain. Additionally, the advantages and disadvantages of continuously scaling up wind turbines are being brought up for discussion within the sector itself.
Economies of scale
Also, the question arises about the potential for standardisation and industrialisation of the wind turbines and the supply chain involved in manufacturing, transport, and installation. As long as the capacity of turbines continues to change, it will be difcult to achieve economies of scale through standardisation of the design and the components for wind turbines, support structures, installation equipment, et cetera. This means that the trend towards the decrease of costs by the increase in turbine capacity is accompanied by cost disadvantages because of missed standardisation and industrialisation in the wider supply chain, including the O&M phase.
Slowing down
The Netherlands Enterprise Agency (RVO) has assigned a study to DNV Services UK a study on ‘Optimal ofshore wind turbine size and standardisation’ for the Top Consortium Knowledge and Innovation Ofshore Wind (TKI Wind op zee) to fnd answers to the abovementioned questions. Recently the outcome of the study was presented >>
Results of the study study ‘Optimal ofshore wind turbine size and standardisation’
1. The rapid growth in the size of ofshore Wind Turbine Generator (WTG) is expected to slow down in the coming years. DNV does not see any technical limitation for WTGs to grow beyond the current largest ofshore WTG designs. However, analysis shows that further growth does not necessarily result in a lower
Levelised Cost of Energy (LCoE). A direct cost reduction has more potential. 2. In the current fast-growing ofshore wind market, increasing WTG production numbers ofer the opportunity to reduce costs. Larger production numbers generally allow for larger investment in product and production optimisation, and larger production numbers ofer benefts in economies of scale. 3. The cost of energy is found to increase with WTG rating. Lower rated turbines, 12-15MW, with high specifc power densities (400-450W/m2) are found to be the most cost-optimal.
For high specifc power densities, the
LCoE is found to show no signifcant variation with respect to WTG rating in the range of 12-20MW. 4. This indicates that the choice of optimal turbine confguration is not straightforward and may depend on parameters other than WTG rating and rotor diameter. 5. It is found that site conditions and discount rates have a strong infuence on the cost of energy. Turbine design choices like design tip speed ratio and drivetrain confguration impact the
LCoE to a lesser but still signifcant extent. The LCoE is also sensitive to
O&M modelling assumptions. 6. Based on the performed assessments,
DNV expects that up to 2030-2035, leading ofshore WTG manufacturers will mainly focus on their current largest design WTG platforms and future upgrades that enable small growth steps. It is expected that the platform lifecycle ends with 14-18MW range platforms carrying rotors with diameters in the range of 230-250m.
After 2030-2035, next-generation
WTG platforms will be introduced with a limited increase in size compared to the platforms they replace. These will however be highly cost optimised by new technologies and will be operated and maintained following new strategies. WTG sizes are expected to go up to 18-24MW with rotor diameters in the range of 250-265m. 7. LCoE values are sensitive to several infuential factors for which best estimates were made but could change over time. Examples of these are the cost price of raw materials and labour, discount rates and
Operational Expenditures (OpEx).
Signifcant future changes in any of these factors can infuence conclusions on optimal WTG size.
during a webinar organised by TKI Wind op Zee. Based on a combined numerical and qualitative assessment the main conclusion of the report is that the rapid growth in ofshore Wind Turbine Generator (WTG) size is expected to slow down in the coming years. DNV does not see any technical limitation for WTGs to grow in size beyond the current largest ofshore WTG designs, but numerical analysis shows that further growth does not result in lowering the Levelised Cost of Energy (LCoE).
Direct cost reduction
Sensitivity analysis applying diferent future learning rates shows that direct cost reduction has much more potential to lower LCoE. In the current fast-growing ofshore wind market, increasing WTG production numbers ofer the opportunity to reduce costs. Larger production numbers generally allow for larger investment in product and production optimisation (standardisation and industrialisation, transport, installation, servicing), and larger production numbers ofer benefts in economies of scale. To take advantage of this, the industry needs to shift focus from new product development to product improvement, and up-scaling and optimisation of manufacturing processes.
Small growth steps
DNV expects that, up to 2030-2035, the leading ofshore WTG manufacturers will mainly focus on their current largest design WTG platforms and future upgrades that enable small growth steps. It is expected that the platform lifecycle ends with 14-18MW range platforms carrying rotors with diameters in the range of 230-250m. After 2030-2035, it is expected that next-generation WTG platforms will be introduced with a limited increase in size compared to the platforms they replace. These new WTG platforms will however be highly cost optimised, feature many new technologies, and will be operated and maintained following new strategies. WTG sizes are expected to go up to 18-24MW with rotor diameters in the range of 250-265m.
