DAF-Indal[1] began working with Canada’s National Research Council and provincial utilities to develop Darrieus wind turbines using Canada’s abundant aluminum in the mid 1970s.[2]
They constructed about a dozen small prototype Darrieus turbines less than 5 meters in diameter and about 9 meters tall in the mid to late 1970s, rated variously from 4 kW to 12 kW.[3] One was installed in the Arctic for Canada’s Defence Research Establishment.[4] Another was installed in Texas at the USDA’s Bushland Experiment Station in a wind-assisted pumping test. Another was installed on Block Island, Rhode Island.[5] One was still standing—inoperative–outside Toronto in 2007.[6]
The Canadian company also developed a series of larger, commercial-scale turbines of 50 kW, 230 kW, and ultimately 500 kW capacities.
Of these, the 50 kW model was the most widely deployed with nearly a dozen turbines installed in Canada, the USA, and Australia. At least two of these were likely “pre-delivery” units installed in the Toronto area for later installation elsewhere. One was installed on Toronto Island.[7] The other was installed at the company’s plant in a Toronto suburb.[8]
The nominally 50 kW turbines used a rotor 11.2 meters in diameter with a height of 16.8 meters.[9] At the USDA’s Bushland Experiment Station, the turbine was downrated to 40 kW because of its use in a wind-assisted pumping application.
50 kW Installations in Canada
- Toronto Island, Ontario: 1977
- Sudbury, Ontario: 1977[10]
- Holyrood, Newfoundland June 1978[11]
- Swiftcurrent, Saskatchewan: Bearing failed 1978
- St. Elanors, Prince Edward Island: 1979
- Mississuaga, Ontario: February 1980[12]
- Christopher Point, British Columbia: April 1980
- Churchill, Manitoba: Post 1980
50 kW Installations in the USA[13]
- Bushland, Texas: 1978[14]
- Pacheco Pass, California: 1981
- San Gorgonio Pass, California: 1982
50 kW Installation in Australia[15]
- Rottnest Island, Western Australia
Unlike other manufacturers who scaled up their designs as they gained experience, DAF-Indal developed two designs simultaneously. While DAF-Indal was developing the 50 kW, 11.2 meter model in 1976, it was also developing a much larger turbine. In the same year that they installed a 50 kW unit in Sudbury, Ontario, they were also installing a 230-kW Darrieus prototype for Hydro-Quebec in the Gulf of St. Lawrence. This turbine was a giant in its day. The rotor spanned 24.4 meters in diameter with a height of 21.3 meters, sweeping 595 m² of the wind stream.[16]
The experimental turbine soon became well-known for an infamous episode disproving the adage that Darrieus turbines are not self-starting.
Darrieus turbines are typically not self-starting, though it is now known that Darrieus turbines can self-start under the right wind conditions. These conditions–though infrequent–do occur. When the Darrieus rotor is at a standstill, only the wind across the ground acts on the blades. Because the pitch of the blades are fixed, the blades stall, there’s no lift or torque, and the rotor doesn’t move. Normally, the rotor must be motored up to speed. But the event on the Îles-de-la-Madeleine changed all that and added a new corollary to Murphy’s Law: “Wind turbines that won’t self-start, will.”
Adapted from Wind Energy for the Rest of Us: A Comprehensive Guide to Wind Power and How to Use It, pages 143-146. There are more references to DAF-Indal elsewhere in Chapter 6. Vertical-Axis and Darrieus Wind Turbines.
On July 6, 1978 the turbine was disengaged from its braking system in light winds during routine maintenance. The turbine was left unattended overnight. During the night, the wind picked up. To everyone’s surprise the next morning, the rotor was turning, slowly at first, but eventually it began to pick up speed.
The DAF-Indal design was unique for the period. Designers had correctly identified one of the fundamental flaws of the Φ-configuration rotor: There is no way to change the pitch of the blades to reduce lift and bring the rotor under control during emergency conditions. Thus, DAF-Indal’s designers provided air brakes at the equator (the widest part) of the rotor. These metal flaps would deploy at high rotor speeds and were intended to keep the rotor from self-destruction.
The air brakes deployed as expected. Unfortunately, as the rotor slowed down the metal plates returned to the normal position, allowing the rotor to again speed up. At some point while the air brakes were cycling from one position to another, one of them became stuck in the running or normal position. The rotor sped up and eventually leapt off the tower, corkscrewing itself into the ground.[17]
It was an embarrassing failure, but DAF-Indal and Hydro Quebec replaced the destroyed turbine with another—improved–version in 1980. One of the lessons learned—a lesson repeated many times in the wind industry since—was the necessity to include a brake on the low-speed shaft as opposed to the less expensive approach of placing the mechanical brake on the high-speed side of the gearbox. The second turbine wasn’t “retired” by Hydro Quebec until 1986. What is little known in the English-speaking world is that this turbine was still standing as a forlorn tourist attraction on the remote windswept island as late as 2016.[18]
The penchant for VAWT promoters to install their turbines on buildings isn’t a modern phenomenon. DAF-Indal had already installed one of their small 4-kW turbines on an Ottawa, Ontario model home in 1978.[19]
In another noteworthy—if shockingly unwise—effort to find markets for its products, they installed the 50 kW version atop a school in St. Eleanors on Prince Edward Island (PEI) in 1979. This remains the granddaddy of all rooftop VAWT installations to this day. After Malcolm Lodge, one of Canada’s early wind pioneers convinced the National Research Council and DAF-Indal that this was an accident waiting to happen, they moved the turbine to the Atlantic Wind Test Site on the windy north end of the island where Lodge was program manager.[20]
At the time, many were trying to find the right application for Φ-configuration Darrieus turbines in North America. West of Amarillo, Nolan Clark’s team at the US Department of Agriculture’s experiment station in Bushland, Texas had installed one of DAF-Indal’s 4 kW turbines in a wind-pumping system. In March 1978 the USDA replaced its 4-kW turbine with its big brother, a 40-kW machine in a wind-diesel demonstration project.[21]
Late in its development cycle, DAF-Indal developed a much more powerful version of their 24-meter, 230-kW turbine, replacing the DAF-Indal blade with a blade extruded by Alcoa that used a wider chord. They also stepped up the rotor speed. These two measures gave them the 500 kW rating that they were seeking.[22]
DAF-Indal dubbed the 500 kW as the “Series 6400,” representing the rotor’s swept area in square feet (595 m²).[23] This simple designation set DAF-Indal apart from nearly all North American manufacturers at the time where the emphasis was on the rated kW capacity and not swept area. However, DAF-Indal and their European competitors understood that it was swept area that determined output.
They installed one of the 500 kW versions at the Atlantic Wind Test Site and another at Southern California Edison’s Devers substation in the San Gorgonio Pass in 1983.[24] When a guy-cable shackle failed on the latter turbine during pre-commissioning, the rotor collapsed taking with it Eric Wright, a young DAF-Indal engineer. The second 500-kW turbine ran for a few years on Prince Edward Island, says Lodge, before one of the blades failed at the blade-strut joint in 1983, flinging the blade into one of the guy cables and bringing the whole turbine tumbling down.[25] DAF-Indal replaced the turbine and testing continued for a few years until the company walked away from Darrieus turbines for good in 1991.[26]
In 1997, meteorologist Jim Salmon reported that the 50 kW DAF-Indal turbine at Christopher Point, on the southern tip of Vancouver Island, west of Victoria, British Columbia had been in continuous service for 16 years. During that time the turbine had operated 35,000 hours and generated nearly 600,000 kWh. This is likely a world record for a single Darrieus turbine in this size class.
In 2004, there were two derelict DAF-Indal turbines still standing at PEI’s Atlantic Wind Test Site when I visited. One used a conventional tubular torque tube, but the other used an unusual lattice mast for the torque tube.
DAF-Indal’s wind turbines were bedeviled by the use of problematic aluminum extrusions as a blade material. Most of their turbines that failed—and most did—failed by fatigue at the blade root or the junction of the blade with the horizontal strut. They were not the only manufacturer of Darrieus turbines during that period to encounter this problem. FloWind and Alcoa also frequently ran into the same issue with their Darrieus wind turbines.
However, DAF-Indal’s designers were insightful to include air brakes or spoilers on their 50 kW ad 230 kW versions. No other VAWTs in North America used air brakes to protect the rotor from destruction during an overspeed emergency. Nor do I remember air brakes being used on any European Darrieus designs. Though the air brakes failed in their first major test on the Îles-de-la-Madeleine, DAF-Indal and the National Research Council learned what went wrong and how to fix them so they would work more reliably in the future.[27] Despite this knowledge, DAF-Indal abandoned the air brakes on their Series 6400-500 kW turbine in the interest of simplicity.
The Canadian fabricator also fell prey to the desire to ship as many turbines as possible to far-flung locations. North America is a huge continent, trying to service wind turbines from British Columbia to California and Texas, and to remote locations like Churchill, Manitoba on Hudson Bay to Holyrood Newfoundland, and the Îles-de-la-Madeleine in the Gulf of St. Lawrence was just asking for trouble. If they’d kept their turbines closer to home in Ontario, they might have had more opportunity to catch problems before they became disastrous.
They were not alone in this. All other North American manufacturers shipped their turbines everywhere they could, and this cost them dearly. In contrast, Denmark is a small country, and the Danes sold turbines first in their home market where they could often see their wind turbines from their windows. They could fix their turbines easily and make quick iterations of their design as they “learned by doing.” Like their North American counterparts, they too ran into problems when they began shipping wind turbines thousands of miles to California.
In the end, DAF-Indal was the most successful of the government-funded, private sector efforts to develop Darrieus turbines. They put more turbines in the field than either Alcoa or Sandia. But their record pales in comparison to the commercial success of FloWind.
Though the American company was launched several years behind their Canadian counterpart, they ended up going much further. FloWind didn’t install their first prototype until 1982.[28] Yet by the mid 1980s, FloWind was operating fleets of Darrieus wind turbines in the Altamont and Tehachapi passes. By 1987 FloWind was generating more than 100 million kWh per year. FloWind’s Darrieus turbines ultimately produced nearly 1 TWh of wind-generated electricity during the two decades they were in operation before bringing the Darrieus wind turbine era to a close.[29]
[1] DAF (Dominion Aluminum Fabricators) merged with Indal sometime before the mid 1970s when this story begins. The company’s literature doesn’t use the hyphen, identifying the company simply DAF Indal. However, the Canadians themselves have hyphenated the name at times. I began hyphenating the name long ago and to remain consistent with my previous work will continue to hyphenate the name here. DAF-Indal was located in Mississauga, Ontario, an industrial suburb west of Toronto.
[2] NRC researchers Raj Rangi and Peter South literally reinvented the Darrieus concept in the mid 1960s. At the time, Canada–in particular Quebec–used its cheap hydroelectricity to refine aluminum that could be extruded into Darrieus wind turbine blades. Consequently, Canada became a center of Vertical-Axis Wind Turbine development.
[3] “Vertical Axis Wind Turbines by DAF Indal Ltd.” (DAF-Indal, Mid 1980s), https://www.windsofchange.dk/downloads.php?a=125&t=1&f=DafIndal.pdf, page 7.
[4] Sean Tudor, “A Brief History of Wind Power Development in Canada 1960s-1990s” (Ottawa, Canada: Canada Science and Technology Museum, 2010), http://www.inference.org.uk/sustainable/images/blyth/A%20Brief%20History%20of%20Wind%20Power%20Development%20in%20Canada.pdf.
[5] Henry Dupont, “Block Island Darrieus Turbine?,” December 13, 2024, e-mail. The story is almost comical if it hadn’t been so dangerous. A bar owner brought the turbine to the island, installed it near a tall building, and was never able to connect it to the island’s grid. He was demonstrating it unloaded one day and found the brake wasn’t strong enough to stop it without a load. He threw rags into the gears to bind up the drive train to stop it—a drastic solution that apparently worked.
[6] The turbine at the Kortright Centre outside Toronto was tied off in 2007 and hadn’t operated for decades. It’s now a museum piece and should be preserved.
[7] Tudor, 2010, p. 6. Anyone familiar with the Toronto area would find this location surprising. There’s an airport on Toronto Island serving regional flights. The airport and the island’s inhabitants were a hot bed of opposition to the Lagerwey wind turbine at Exposition Place.
[8] L. A. Schienbein, “Performance Testing of a 50 kW VAWT in a Built-up Environment,” 1981, https://ntrs.nasa.gov/citations/19820015822.
[9] Paul N. Vosburgh, Commercial Applications of Wind Power (New York : Van Nostrand Reinhold Co., 1983), http://archive.org/details/commercialapplic0000vosb, page 42.
[10] Tudor, 2010, page 6.
[11] W.A. Vachon, “Large Wind Turbine Generator Performance Assessment Technology Status Report No. 26889171.Pdf,” October 1980, https://www.osti.gov/servlets/purl/6889171, pages 2-3.
[12] Schienbein, 1981. This turbine was installed for a “pre-delivery test” so it was likely moved to another location when the test was completed.
[13] Vosburgh, 1983, page 96.
[14] Vaughn Nelson and Meg Mooring, “Biennial Summary September 1977-August 1979” (Canyon, Texas: Alternative Energy Institute, West Texas State University, December 1979), Texas Documents Section E:28.13: 1 – 28, page 6.
[15] “Vertical Axis Wind Turbines by DAF-Indal,” p. 2
[16] Vosburgh, 1983, page 42. And Erik Möllerström et al., “A Historical Review of Vertical Axis Wind Turbines Rated 100 kW and Above,” Renewable and Sustainable Energy Reviews 105 (May 1, 2019): 1–13, https://doi.org/10.1016/j.rser.2018.12.022.
[17] R. J. Templin, “Design Characteristics of the 224 kW Magdalen Islands VAWT” (Ottawa, Canada: National Research Council of Canada Ottawa Ontario, Canada, 1979), 12, https://ntrs.nasa.gov/citations/19800008203, page 143.
[18] Paul Gipe, “Abandoned DAF-Indal Darrieus Turbine on the Iles-de-La-Madeleine,” WIND WORKS (blog), December 1, 2017, https://wind-works.org/abandoned-daf-indal-darrieus-turbine-on-the-iles-de-la-madeleine/.
[19] Tudor, 2010, page 5.
[20] Jim Salmon and Malcolm Lodge, “DAF-Indal 50 kW Longest Lived Canadian Darrieus,” March 7, 2013, e-mail.
[21] Nelson and Mooring, 1979, p. 2
[22] Vosburgh, 1983, page 61.
[23] P. J. Penna, “The DAF-Indal Ltd. Series 6400 VAWT at the Atlantic Wind Test Site: Performance and Structural Dynamic Test Data,” in Intersol Eighty Five, ed. E. Bilgen and K. G. T. Hollands (Oxford: Pergamon, 1986), 2167–71, https://doi.org/10.1016/B978-0-08-033177-5.50408-7.
[24] I logged the death of Eric Wright in 1983 in my database of mortality in the wind industry.
[25] Jim Salmon and Malcolm Lodge, “DAF-Indal 50 kW Longest Lived Canadian Darrieus,” March 7, 2013, e-mail.
[26] Malcolm Lodge, “DAF Indal? Sudbury,” January 17, 2018, e-mail.
[27] Templin, 1979, page 146.
[28] Vosburg, 1983, page 68.
[29] Paul Gipe, “FloWind: The World’s Most Successful VAWT (Vertical Axis Wind Turbine),” WIND WORKS (blog), February 7, 2013, https://wind-works.org/flowind-the-worlds-most-successful-vawt-vertical-axis-wind-turbine/.
