Those around in the late 1970s may remember seeing magazine photographs of Danish students and volunteers carrying a massive wind turbine blade out of a tent (see Figure 13). (Karnøe and Garud, 2012; Tvindkraft, n.d.). That photo captured the world’s imagination. It was one of those rare historical moments that became a beacon to citizens everywhere who wanted to develop renewable energy by themselves, for themselves, and for their community’s benefit.
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| Figure 13. Tvind people power. The photo seen around the world in 1978 as students at the Tvind School carry one of the wind turbine blades from its assembly hall to the wind turbine. The action sent a political message: Together we are strong. We want wind power and we will build it ourselves. (Tvind School). |
They were not ordinary students. They were on a mission and they knew at the time they were undertaking an historic task. They had set out to prove to the Danish government that Denmark didn’t need nuclear power, that Denmark with its long history of working with the wind could once again do so. They made another message clear too. If the Danish government wouldn’t act, the people would take the matter into their own hands, as they were doing that historic day, and build their own wind turbines.
Tvind was not an ordinary school either. Located near Ulfborg on the windy west coast of Denmark’s Jutland peninsula, the Tvind School was unlike a school in the modern sense and more in the tradition of the Danish folkehøjskole movement founded in the mid-19th century by Danish theologian N.F.S. Grundtvig. It was more like the training school founded by Poul La Cour at Askov than a public school. Not surprisingly, Tvind has had a similar influence on the development of wind energy in the contemporary era as the folkehøjskole at Askov had at the turn of the 19th century.
In the retelling of the modern wind industry’s early history, the construction of the wind turbine by Tvind and its role in pioneering modern wind turbine blades is often overlooked. It’s an uncomfortable story for many still, because the implications are so profound. How could a group of students, their teachers, and volunteers accomplish what some of the world’s most sophisticated aerospace firms with millions in research money could not? How could they build what was then the world’s largest wind turbine—a machine that has operated for more than three decades and remains in service to this day—when Boeing, Westinghouse, General Electric, Hamilton Standard, Kaman, Messerschmidt-Bölkow-Blohm, MAN and others had all failed, their turbines dismantled and sold for scrap?
The work at Tvind was taking place at the same time as NASA was developing its Mod-0A series and GE’s subsequent Mod-1. The difference in outcomes couldn’t have been starker.
The message delivered by the Tvind School so long ago was that wind energy was too important to be left to aerospace giants, electric utilities, and even to national governments. They demonstrated that unlike nuclear power, which requires massive centralized institutions, wind turbines could be built and owned by common citizens. This is a message that still resonates today.
Of course, the Tvind design team had sophisticated engineering knowledge. They and their faculty were not the Luddites some have portrayed. The school received valuable technical assistance from Helge Petersen and others from what would become Risø’s test station for wind turbines and from the Danish Technical University, for example. This was beneficial to all parties. Tvind was able to deal with some thorny technical problems, while the technical establishment gained valuable experience and hands-on knowledge of a large wind turbine outside the official Danish wind program.
And yes, they built upon a long Danish tradition with wind energy. But they were also willing to depart from that tradition when necessary. After all, they set out to build the first Danish wind turbine using long cantilevered blades instead of a rotor braced with the struts and stays like Juul had used at Gedser. They intended to build what was then considered a “modern” turbine, one that used cantilevered blades mounted downwind of the tower. Just as importantly, they were also willing to borrow good ideas from others, including from their southern neighbor, Germany. It was in this that they made their most significant technical contribution.
Tvind studiously avoided the common affliction that infects most design teams—the Not-Invented-Here syndrome. There’s a natural human tendency to want to go it alone, to be the sole inventor of a new idea and to discount the work of others and ignore the lessons they learned—often at great expense.
To build a long cantilevered blade the Tvind design team knew they needed a strong attachment at the blade’s root. Only a few decades earlier, Hütter had demonstrated just how to do so. Tvind’s development team adopted the concept as its own. The blades the Tvind team were building were no ordinary blades. They were big, each was 27 m long—as long as the blade that failed on the Smith-Putnam turbine in 1945. And massive, each blade weighed 5200 kg. The blades were nearly as big as those being developed at the same time by GE for its unsuccessful Mod-1 turbine.
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| Figure 14. Tvind blade. The late Preben Maegaard, one of the pioneers in the Danish wind revival, stands by the root end of one of the original Tvind blades. The blade is part of Danmarks Vindkrafthistoriske Samling collection of historic Danish wind turbines and components and can be seen at the Folkecenter for Renewable Energy near Hurup, Denmark. The 27-m long blade weighs 5200 kg. Note the blade flange where it mounts to the hub. The flange and the technique for attaching the fiberglass in the blade to the flange were originally developed by Ulrich Hütter in the 1950s and 1960s. Tvind adapted the technique to its pioneering wind turbine in 1975. |
The huge Tvind project was begun in 1975 and finally completed in 1978. At the time it was the largest wind turbine in the world. It hasn’t been all smooth sailing. Out of safety concerns, the original 2 MW design was downgraded to 1 MW and half of this has been used for heating the Tvind school complex because the local grid wasn’t able to take the full 1 MW.
One blade failed in 1993 after 15 years of operation, requiring replacement of the rotor. The turbine was later returned to service and it was still operating in 2021[2024!]. This is a remarkable accomplishment for any wind turbine, and more so for such an early turbine and for one so large.
At the same time as Tvind was building the big wind turbine, a team of students developed an 11-kW downwind turbine using the same blade mounting technology they were using on the large turbine. In the spirit of La Cour, Tvind then made the design of these 4.5 m long blades available to others.
Tvind’s blade design—primarily its use of the Hütter flange—and their willingness to share the technology they had developed with other experimenters was the key element that led to what would become today’s wind industry, say Danish wind historians. All that was missing was someone to commercialize the blade technology (Maegaard et al., 2013).
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| Figure 15. Tvindkraft. World famous megawatt-scale wind turbine installed by students at the Tvind School near Ulfborg on the west coast of Jutland in 1978. Like other pioneering Danish wind turbines, the Tvind turbine is still operating after more than three decades—long after other large turbines installed during the period had been removed and sold for scrap. The turbine’s striking pop art paint scheme was created in 1999 by architect Jan Utzon to celebrate the turbine’s 25th anniversary. Utzon is the son of the architect who designed the Sydney Opera House. |
[Read more here and here]
The rest is history.
Thanks to these energetic pioneers, who succeeded when all the experts failed, wind, together with solar, will eventually power our grid. In 2023, their combined total was 13.3% of global electricity generation. In 2003, that was 0.4%. That's a compound growth rate a touch under 20% per annum, which, if sustained, will lead to wind and solar reaching 80% of global electricity generation by 2033. Will that sort of growth rate be sustained? Who knows? My guess is yes: wind, solar, and battery costs continue to decline, while coal and gas get no cheaper.
But those who twenty years ago mocked renewables because they provided less than half a percent of electricity, will no doubt be saying, I always told you they would work.
Luckily for the world, these Danish students and professors didn't take no for an answer, and their triumph doesn't just live on in the explosive growth of wind power across the world, but in their turbine, the world's first commercial wind turbine, which is still working today, nearly 50 years later.
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