How tall can a wind turbine be? Is bigger always better? How is wind power technology advancing so quickly? And what does it mean that wind power is considered a mature market? Antti Lehtinen, Head of Turbine Technology at Ilmatar, knows what’s going on in wind power right now and where we’re heading.
Can you explain what the rapid technological development in wind power means?
– The principles of wind turbines are the same – three rotor blades, a tower and a generator. What is happening is that the turbines are getting bigger, the towers are getting higher, and therefore the generators are getting bigger. We can compare the turbines launched in the late 1990s with today’s wind turbines. Back then, the rotor diameter was around 50 metres, the hub height was the same, and the capacity was between 600 and 700 kilowatts. Today, in Ilmatar’s onshore wind farms, we are building turbines with a rotor diameter of about 170 metres, a hub height of over 160 metres and a capacity of 7 megawatts. Looking further at offshore wind, we are pilot-testing turbines with a rotor diameter of 236 metres, a hub height of over 150 metres and a capacity of 15 megawatts.
Is higher always better?
– No, it depends on wind conditions and project economics. In some places, lower towers and smaller rotor blades are more suitable. In Finland, we have a lot of forests, which means that the winds are smoother and the turbulence decreases the higher we go, which is one of the reasons we need to build tall.
What applies to offshore wind power?
– Generally, a lower hub height and a large rotor are sufficient for offshore wind power. It costs a lot to build high, and because the wind moves more freely over the sea, you can get high power output even at a lower height. But in the near future, we will reach a total height of over 350 metres, including the rotor blade in an upright position. Where it ends, we can’t say today.
Why is the technology advancing so quickly?
– It’s about need and demand. The market needs more green energy, and the industry responds with technological developments.
How long does a wind turbine built today last?
– Right now, 30-35 years is expected for onshore wind, and soon we will be at the same level for offshore wind.
What is the energy payback period, i.e. when does a turbine start producing more energy than it took to build it?
– It is estimated to be nine months, up to one year. So, over its lifetime, a turbine produces up to 37 times more energy than it takes to build.
Can wind turbines be recycled after their lifetime?
– Today, we are talking about a recycling rate of 90 per cent. The blades have been difficult to recycle in the past, but even here, the technology is advancing as the requirements and needs increase. Ilmatar started collaborating with Stena Recycling last summer, and now the glass fibre materials are reused in cement production. “Even though the cement industry is carbon intensive, we can reduce carbon emissions with these recycled materials. And the more we cooperate and recycle, the more the knowledge increases.
What is the future of wind power technology?
– Regarding onshore wind, we will soon be building 10 megawatt turbines. They are currently testing towers with a hub height of over 200 metres, but it is challenging to go over 170 metres because of the required cranes. It would simply be too expensive. But, the crane industry is constantly evolving, and new solutions are emerging. In offshore wind power, we will build turbines with a capacity of over 20 megawatts within ten years.
Antti Lehtinen, Director of Procurement at Ilmatar