Published on August 13th, 2020 |
by Jesper Berggreen
August 13th, 2020 by Jesper Berggreen
This year the summer in Denmark is presenting very different weather types. A couple of weeks ago we experienced the most stormy and cold days ever in summertime, and as I write this we have a heatwave lasting several days.
One of those windy days I decided to go see the Østerild wind turbine test site, where the largest wind turbine prototypes from Siemens Gamesa, Vestas, MHI Vestas, Envision, and Haliade are being tested before primetime. Last year Denmark passed the magic 50% renewable energy generation milestone, of which 90% was wind, so I thought it was about time I encountered the giants of the giants.
Would you believe it, when I got into my car, it warned me that the cold weather would limit my range! I had not seen that snowflake since winter. Hurray for the age of long range electric vehicles!
I had checked that it was possible to charge my car at the visiting center with 50 kW, and I suspected a row of charge points. It was very disappointing to find only one stall, and in fact it’s kind of embarrassing. Right next to several multi MW turbines pumping out electrons, and they only put up a single 50 kW charger — sigh.
Anyway, the test site at Østerild close to the North Sea in northern Denmark is so large it blows your mind. I only walked out to the first 4 installations out of 8 total (1 more has been added since the satellite image above). The wind was brisk at between 10 — 15 m/s (22 — 33 mph), which is the perfect testing conditions for these huge turbines.
I was struck by the size of these machines. I live close to a couple of 900 kW turbines, but these 6 — 9 MW turbines is in a whole other league. The visiting center is nicely laid out and a cut-in-half demo tower was open to enter and climb up to get a good view of the site.
While walking past these giant machines I listened in awe to the wind pushing the blades. Even though the wind was weak below the tree tops, the noise was quite loud from the blades. A sudden very loud noise made me almost hunker down. The blades twisted to apply maximum brake power and just a few seconds later the rotor had stopped completely. It’s not easy to describe the sound of the amount of air being pushed around here. Shortly after the blades twisted back and rotation started again.
About 100 tests are performed on the Siemens Gamesa Renewable Energy’s prototypes in Østerild during a year. More than 500 sensors are normally part of a turbine control system, but 650 extra sensors were added to the SG 8.0-167 DD prototype as part of its validation. More than 4,000 parameters can be adjusted to optimize the controller of each wind turbine.
These prototypes has a relative short life-time of 2 — 5 years, because they are stress-tested to the max. So these start and stop maneuvers are very frequent. The sound itself gives a clear idea of the sheer amount of power in play here, but also makes you think about the issue of noise. Luckily these very large turbines are meant for the sea.
The non-profit organization stateofgreen.com is behind this site, and this is what the have to say about Denmark’s role in the wind power industry:
Denmark — The global wind energy hub
Wind turbines provide around 40% of Denmark’s electricity consumption, but we plan to go further. By 2021, 50% of the electricity consumption will be generated by wind energy. Today, Denmark is home to more than 4,800 [onshore] turbines located in 78 out of 98 Danish municipalities. The turbines produce electricity equal to the consumption of 500,000 households.
Global hub for wind energy innovation
In Denmark, the wind industry employs more than 31,000 people. The availability of a highly skilled workforce, superb facilities for testing prototypes and a comprehensive network of companies, research institutions and government research programmes make up an innovative R&D environment like no other place in the world.
The future of wind energy
In Denmark, you can test all parts of a wind turbine, Wind turbine technology has changed dramatically over the past few decades. While most turbines produced in the early 1990s had sizes of up to 225 kWh, the turbines tested here at Østerild reach a capacity close to 10 MW.
Wind energy for all
The large amount of wind energy in the Danish electricity grid is possible because the grid is connected to our neighbouring countries, This allows for the import and export of energy during peak periods. At the same time, security of supply is very high. Danes have electricity in the socket 99.997% of the time, and onshore wind energy is actually one of the cheapest sources of energy in Denmark.
All in all, I was left with a comprehensive notion of the complexity of this industry and the history of how the technology has matured to the truly competitive energy supply systems the world needs today to help send the use of fossil fuels into the dark ages.
Wind is king! However, passing a 60 MW solar photovoltaic plant being built nearby on the way home, I get the feeling that solar will dominate sooner than we think. Both technologies will obviously coexist for many years to come, but as batteries get cheaper, it is without a doubt easier and cheaper to build solar, and as a bonus the noise disappears.
Land use, you ask? You would think solar takes up much more space, but take a look at the satellite image above once more and compare with the one below. Those 8 turbines take up 5 km in a straight line, about 200 m wide, that’s 1 km². These turbines combined would be able to produce about 60 MW in optimal wind conditions.
The sun can deliver about 1 kW peak power on each m² in this part of the planet’s surface, so 1 km² densely covered with 20% efficient solar PV panels could generate about 200 MW in optimal sunlight. I know, it’s a very different kind of intermittency, and that’s why solar and wind work so well hand in hand, but you cannot ignore the potential of solar when you do the math, especially in cost terms. Oil, gas, and coal are going away, not because they are dirty, but because they are expensive.
Wind is inherently mechanical and has a somewhat linear historical efficiency progression. Solar is essentially electronics and has an exponential efficiency progression. Nevertheless, it is truly amazing how much wind power technology has advanced, and I think we will witness at least a doubling in power per turbine before solar takes over completely, and still, wind will be the choice in remote, windy, and dark areas of the globe.
All photos by Jesper Berggreen
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