The Rest of the Story: Part 2 of History of Conventional Wind Turbines–the 1970s onward

By Paul Gipe

The historical saga begun by Erik Möllerström and myself finally reaches its conclusion with the publication of Part 2 in Wind Engineering, an imprint of Sage Journals.

Titled An overview of the history of wind turbine development: Part II–The 1970s onward, the journal article traces the development of modern wind turbines from the Great Wind Revival in Denmark in the early 1970s through to the great California wind rush of the mid 1980s with stops along the way for the rise–and fall–of the giants built by the aerospace industry.

As a participant in and a witness to the California wind rush, the second part of our two-part series relies largely on my view of the events that took place in that exciting period, buttressed by observations of engineers and academics on both sides of the Atlantic.

No need to repeat all of that here, but I thought it useful to highlight a few photos from Part 2.

Growian, the German giant that went nowhere.

Growian. One of German engineering’s most spectacular failures was Growian (Grosse Wind Energie Anlage). The downwind, 100-m (330-ft) diameter turbine operated only 400 hours between the time it was installed in 1983 and when it was taken out of service in 1987. Growian operated even less than the Smith-Putnam turbine in Vermont in 1945. It was more than two decades before German manufacturers again ventured to this size. The two guyed towers are meteorological masts at what was to become the Kaiser-Wilhelm-Koog test center. 1987.

Tvindkraft, the giant that shook the world.

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).

Tvindkraft as it stands today, still operating 45 years after it was installed near Ulborg, Denmark.

Lightweight vs Heavyweight Designs

I characterize American designs of the period as “lightweights in a heavyweight” environment. The wind is a harsh master and many engineers learned this the hard way on both sides of the Atlantic.

Turbines characterizing lightweight designs of the early 1980s include Storm Master, Windtech, and ESI. ESI was a commercial spin-off from the US wind R&D program. The ESI turbines were distinctive for their fairly large diameter (comparable to that of Danish turbines), the high speed of their rotors, and the tip brake at the end of each blade. The tip brakes, or flaps, were intended to protect the turbine during high wind emergencies. The design used two fixed-pitch, wood-epoxy blades downwind of its hinged, lattice tower. Two versions were introduced. Nearly 700 of the ESI-54 (16.4-m), and 50 of the ESI-80 (24-m) were eventually installed in California.

ESI-80. Another US-built series that followed Hütter’s design philosophy were the ESI-54 and the later ESI-80 shown here. The ESI turbines also used a downwind, two-blade, teetered rotor driving an induction generator through an integrated gearbox. The brake is mounted on the back-end of the generator (far left). ESI used tip-brakes like those on the Isle of Man turbine, not pitchable-blade tips. The high rotor speed in combination with the downwind design and tip brakes was notoriously noisy. The ESI-80 used an 24-m rotor made up of laminated wood blades coupled to a 250-kW generator. Circa mid to late1990s.

Silent wind revolution

We also explore what French engineer Bernard Chabot characterizes as a silent wind revolution. It doesn’t garner headlines or breathless prose. It’s not sexy new technology. It’s as old as wind energy itself and we’ve known how to do it and why since before Ulrich Hütter codified it in the 1950s.

This revolution is being led by large diameter wind turbines with relatively low generator ratings. These wind turbines look exactly like the wind turbines that they supersede with the exception that maybe the blades are a little longer, a little more slender, and a little more flexible than previously. This is the technology that makes high penetration of wind energy more likely than ever before because it reduces the need for storage and new high-voltage transmission capacity. These are wind turbines designed for low and moderate wind regimes—the places where people live.

Our conclusion?

Modern wind turbine design for use on land has coalesced around a standard configuration of a large diameter rotor using three blades upwind of the tower with high specific swept area relative to rated generator capacity. It was small-scale Danish manufacturers in the 1970—1980s, skilled at serving an agricultural market that developed products which evolved into the commercial wind turbines of today, and not the governmental-funded wind programs with large-scale prototypes developed by the aerospace industry.

Wind energy’s success grew from the ground up not from the top down.

Unlike many academic articles that can only be read behind a pay wall, our historical review is openly accessible and available for download. See An overview of the history of wind turbine development: Part II–The 1970s onward.