The rapidly growing global wind industry is continuously scaling its range of onshore and offshore wind turbines upwards through gradual innovation and increasingly bolder out-of-the-box solutions. As stated in the study “Wind Energy in Europe: 2021 statistics and the outlook for 2022-2026” published by WindEurope in February of this year, the nominal output of newly installed onshore wind turbines averaged 4 MW in 2021. In comparison, this value in 2021 for newly ordered wind turbines was already 4.9 MW (i.e. +2.5% higher).
For new orders for offshore wind turbines, the value grew to 11.2 MW in 2021 compared to 8.5 MW of new installations in the previous year, an increase of +31.8%. In 2020, the value was still 8.3 MW. A significant factor that contributed to the recent sharp increase in the nominal output of offshore wind turbines was the one hundred 14 MW Siemens Gamesa SG 14-222 DD wind turbines for British waters ordered in the first half of 2021. This model is currently the most powerful wind turbine in the prototype stage. It also has the largest rotor diameter in the industry at 222 m.
When scaling up wind turbines, not only the rated power (in MW), but also the wind conditions must be taken into account. China, for example, is a predominantly weak-winded region, but typhoons also occur there. In contrast, the North Sea is a typical strong wind area. A large rotor can compensate for weak winds due to the enlarged rotor surface. However, challenges arise in a predominantly weak-winded area when hurricanes occasionally occur. Exhibitors at WindEnergy Hamburg who are active in such markets can advise trade fair visitors in this regard.
Optimizing the design means achieving an optimal specific ratio between turbine power and painted rotor circuit area; for a 13 MW turbine, a rotor diameter of 220 m is sufficient in a high-wind area, while in a low-winded region you are more likely to choose a 245 m rotor.
OEM manufacturers and specialized consulting companies such as AEROVIDE and Bewind can inform trade fair visitors about different solutions and optimal system configurations.
Offshore wind energy
Since the opening of the world’s first wind farm in 1991 with 11 wind turbines of 450 kW each, the size of offshore wind turbines has evolved to the current 14-16 MW class. On the 2011/12 introduced 6 MW or 8 MW platforms from Siemens (Gamesa) or (MHI) Vestas gradually followed larger plants in the next few years. This development path was abruptly interrupted when GE Vernova suddenly presented its 12 MW Haliade X direct drive turbine with 220 m rotor in 2018.
The competition reacted with corresponding new developments. In this highly dynamic market environment, Vestas is installing a medium-speed 15-MW prototype with a rotor diameter of 236 m this year, and Siemens Gamesa is installing a 14 MW prototype with direct drive and the same rotor size.
Departure into new dimensions
Other companies in the wind energy industry are already looking beyond this magnitude. At the beginning of this year, a Dutch technology institute predicted that by 2040 horizontal axis wind turbines with nominal outputs of 27 MW and blade lengths of about 145 m – i.e. Rotor diameters of about 297 m – would be the norm. Danish developer Ørsted made headlines with an environmental impact study for a Swedish offshore wind farm with 55 wind turbines of 27 MW each and rotor diameters of up to 320 m; commissioning is planned for the late 2020s, it is said.
The perspective of ship designers and operators
Leading consulting companies for marine technology such as GustoMSC and installation companies such as Van Oord, Jan de Nul and DEME Offshore will present their expectations regarding future wind turbine sizes at WindEnergy Hamburg. The latest mega-class jack-up ship designs at different stages of development are designed for the installation of the new wind turbines from 20 MW with rotor diameters of an estimated 275-290 m.
The further development in the field of offshore wind turbines is not limited to single rotor concepts. Different multirotor wind turbines with floating platforms are under development. They have considerable scaling potential, for example in the form of a 32 megawatt unit with two 16 megawatt turbines.
Onshore wind energy
The size of onshore wind turbines has also developed from modest 10-15 kW in the late seventies to the latest 5.5-7 megawatt flagship models with rotor sizes of over 172 m for non-Chinese markets. Within China, some suppliers already offer models with rotors in the range of 180-190 m and above. Optimized for low production costs, these low-wind models also aim to eliminate subsidies in this market in the future.
An end to the size development of onshore wind turbines is repeatedly predicted. A main argument is the transport of the bulky rotor blades on the road. However, even rotor blades with lengths of 84-85 m can still be transported by road in well-developed markets, because the transport vehicles have co-developed. At some point, however, a switch to segmented rotor blades should no longer be avoided. For example, the Spanish manufacturer Nabrawind already offers a modular solution called Nabrajoint.
But other obstacles also oppose further upward scaling in the onshore market: the permitable hub and/or blade tip height, limits of transport logistics and increasing difficulties in the assembly of the gondolas and towers. As a solution, the Spanish exhibitor offers HWS self-climbing cranes. Enercon uses an internally developed crane solution for its modular steel towers.
In contrast to the offshore segment, where direct-powered wind turbines and medium-speed transmission systems dominate, high-speed, non-integrated transmission solutions are usually still common in the onshore sector. The pioneers of medium-speed onshore transmission turbines were WindEnergy Hamburg exhibitors AEROVIDE, aerodyn-engineering and Vestas. The exhibitors Eickhoff and Winergy (Flender) as well as ZF Wind Power are specialized in transmission drive strands. Enercon relies on internally developed direct drive solutions.
At present, it is still difficult to predict whether and when the size growth of wind turbines will reach insurmountable technical, logistical, licensing, economic or other limits.
WindEnergy Hamburg from 27th – 30th September 2022
Every two years, one of the most exciting industries meets on the world’s leading networking hub for wind energy: At WindEnergy Hamburg in the heart of the vibrant Hanseatic city, more than 1,400 companies from 40 countries present their innovations and solutions in ten exhibition halls up to 30,000 visitors from 100 nations. Plant manufacturers and suppliers along the entire value chain of wind energy onshore and offshore give a comprehensive market overview on 68,500 m2. Service providers, from planning and project planning, through installation, operation and maintenance, marketing, certification to financing, offer their expertise. The Expo is accompanied by top-class conference sessions on all key topics that move the industry. The WindEnergy Hamburg team designs this program together with its partners, including the global wind energy association GWEC, the European WindEurope association, the national associations VDMA and BWE as well as leading media and exhibitors in the industry. From 27th to 30th September 2022, all sessions will be offered free of charge on four open stages directly in the exhibition halls. Parallel to WindEnergy Hamburg 2022, H2EXPO & CONFERENCE, the new international meeting place for the production, distribution and use of green hydrogen, will also take place for the first time.