In 2020, Vestas will construct a huge prototype – a 15-megawatt (MW) wind turbine with the capacity to power around 13,000 British homes.
It will be the world’s largest wind turbine, though not for long. Wind turbines are continuously getting larger, and it’s happening much faster than anyone anticipated.
The Chinese firm MingYang recently announced a 16MW turbine, for example. The maximum capacity of an offshore turbine was 8MW just four years ago.
“It’s happening faster than we would want,” says Aurélie Nasse, head of offshore product market strategy at Vestas. The firm is one of a few that have pioneered the development of super-sized turbines, but concerns about building bigger turbines are on the rise.
“We’ve been working together for a long time,” she adds when I ask about the sector’s future. “It’s important to make sure it is a long-term race for everyone in the business,” she says, adding that bigger harbors and necessary equipment and installation vessels will be required to transport today’s big turbine components offshore.
Then there are the substantial investments required to get there. “If you look at our [manufacturers], not a single one of us is profitable anymore,” adds Ms. Nasse. This is a considerable hazard.
Vestas’ Aurélie Nass claims that the development of larger turbines is a significant financial gamble.
However, while the wind sector’s eagerness to go further is one of its greatest assets, it is also a double-edged sword. If you’ll pardon the pun, that’s basically what they are. And there are few indications that the rush to build turbines with a capacity of 20 megawatts or more will ease up any time soon.
“It’s stunning,” says Guy Dorrell, a Siemens Gamesa spokesperson about the fact that a single offshore wind farm can now power a million homes. His firm will soon launch an onshore prototype of a 14MW offshore turbine that may be increased to 15 MW by the end of this year.
According to WEC Energy, a single rotation of a 14MW turbine would provide enough electricity for 352 kilometers (218 miles) with the Tesla Model 3. Aside from increased power output, one of the benefits of larger turbines is that they are more efficient in terms of installation time and cost; clearly, you only need one base structure and set of cables for a 14MW turbine versus two for a pair of 7MW machines.
The United Kingdom now has about 10.5 gigawatts (GW) of offshore wind capacity, which is expected to rise fourfold by 2030. According to researchers at Imperial College London, however, this isn’t enough to supply net-zero power by 2035.
Whatever happens, the market is ready and waiting, and you can bet that bigger turbines will become more prevalent. A spokesman for Wind Europe, an industry group.
By 2020, 15MW turbines will be seen as “normal” by Becker, who predicts that they will be commonplace for the next 20 years.
A Tesla automobile would require about 220 miles of charging from a single sweep of a big turbine blade.
It might happen much sooner than that. The UK’s newest offshore wind projects, which will be constructed on Dogger Bank in the North Sea, are expected to utilize 13 and 14-megawatt turbines.
But surely, there must be limits to how big these things can get? They’re already quite overwhelming. Each blade of Vestas’ 15MW turbine is 115.5m (379ft) long, nearly as long as London’s Centre Point skyscraper is tall. The rotor diameter of the turbine is 236m (The Shard in London is 310m high).
“There must be a limit in terms of what one can do,” agrees Simon Hogg, an energy expert at Durham University. The Ørsted chair at the university is endowed by energy firm Ørsted.
Rather, the difficulties of putting these devices in place and keeping them running may be the first ones to arise.
“There are still open questions about the overall environmental impact and the ability of the marine environment to sustain such enormous offshore turbines,” says Professor Deborah Greaves at Plymouth University, regarding super-sized offshore turbines.
While it is true that wind turbines may have some harmful effects on wildlife, the magnitude of this at scale is difficult to quantify. Furthermore, offshore wind farms must be presented with caution to avoid interference with shipping lanes because they are quite large.
There are only a limited amount of vessels that can accommodate the largest turbines.
Professor Hogg adds that the expense of maintaining hundreds of enormous turbines hundreds of kilometers offshore may increase over time. “Anything like that, it might be the deciding factor as to how big offshore wind turbines can get,” he says.
Then there are the technical issues. The really huge turbines are generally positioned far from the ground, which means that the electricity they produce must travel long distances.
When electricity is converted to DC by being passed through a resistor, some of the power is lost. Converting to direct current (DC) is considerably more efficient, but developing technology for using DC at large scales necessitates significant innovations in engineering, according to Prof Hogg.
Assuming the same distance and amount of time are traveled, a very long turbine blade travels faster than a shorter one turning at an identical speed.
To improve the aerodynamics of their blades, jet engine manufacturers have been experimenting with feathering designs since the 1970s. However, current turbine models have a blade tip speed of around 90m/s, or 324km/h (201mph), according to Prof Hogg, which has a “significant influence on the overall aerodynamics of the blade.”
The designer states that the blades are also twisted somewhat near the tip in order to guarantee excellent operation, despite the fact that they may be twisted. That implies you can’t make a blade too big or fast of rotation.
In conclusion, while constructing a wind turbine larger than existing monsters may be feasible from an engineering standpoint, the practicalities and costs of putting them in, operating them, and maintaining them may pose significant roadblocks to their seemingly unstoppable expansion in the future.
“We must be cautious about our speed,” as Ms. Nasse points out.