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Large Wind Turbines

May 22, 2020
Paul Gipe

Power Performance Test on the Ogin 2.2 Ducted Wind Turbine Prototype


I've received a portion of Intertek's 2016 power performance test of Ogin's Model 2.2 150-kW ducted wind turbine "over the transom" as we say. The much hyped and controversial device delivered its rated power in the test.

The 20-meter (66-foot) diameter shroud intercepted 316 m² of the wind stream. This is equivalent in size to wind turbines installed in California's windy passes during the late 1980s. Wind turbines of the period were rated similarly to the Ogin 2.2. For example, the Catalonian manufacturer Ecotecnia rated their 20-meter diameter conventional wind turbine at 150 kW for the European market. Other companies in the same size class rated their turbines at 100 kW, and sometimes less on the European market.

Regardless of its early hype, Ogin's experimental wind turbine delivered more or less what other wind turbines of its size produced in the late 1980s. This is in and of itself remarkable. Few other ducted wind turbines have ever been tested to international standards. Most ducted devices have failed in one way or another before any data on their actual performance in the field had been collected.

To be clear, Ogin's model 2.2 delivered performance comparable to conventional wind turbines with rotors the same size as Ogin's shroud. That is, it did not deliver more performance and certainly not a lot more than that from a conventional wind turbine. This is in contrast to the hype fostered by Ogin's predecessor FloDesign.

In 2008, FloDesign was all over the tech press with claims that their turbine would produce 3 to 4 times more energy from the wind than conventional turbines. Even DOE’s Arpa (Advanced Research Projects Agency) was hyping the device that they had invested $8 million in as a “breakthrough." DOE said FloDesign’s “innovative” wind turbine “could deliver 300% more power than existing wind turbines of the same rotor diameter by extracting more energy over a larger area.”

Note that in DOE's statement they compared "rotor diameters." Yet, FloDesign-Ogin's wind turbine used a large shroud around the "rotor." Thus, DOE was using sleight of hand to justify spending public money in a questionable venture and willingly played along with FloDesign's misleading hype.

Who knows whether it was Arpa's and DOE's misleading press releases that duped the pension funds of New Zealand and Alberta into investing in the ultimately unsuccessful venture?

A ducted wind turbine uses a large shroud or duct around the rotor. The shroud adds to the cost and complexity of the wind turbine. A ducted wind turbine without the duct is just an ordinary, every-day wind turbine. It's the shroud that makes a ducted wind turbine unique and it's the shroud that intercepts the wind.

Comparing the rotor of a conventional wind turbine with the rotor of ducted wind turbine, as DOE did, is like comparing apples and oranges. They are not the same. To compare a conventional wind turbine to a ducted wind turbine you must use the ducted turbine's shroud diameter, not the diameter of the rotor.

The device was tested from 3 March to 28 March 2016 in the windy San Gorgonio Pass near Palm Springs, California. The machine was part of a group of at least six units in a cluster.

The tests were completed over a range of 10-minute average wind speeds from 2 m/s (4.5 mph) to 19.5 m/s (43 mph).

The turbine reached its rated 150 kW power at 13 m/s (29 mph).

Significantly, the device achieved an exceptional Cp (Coefficient of Performance) of 0.48 at average wind speeds from 9.5 m/s (21 mph) through 10.5 m/s (24 mph).

The 20-meter diameter device stood on a tower at a height of 34 meters (110 feet).

The group of ducted turbines, of which the test turbine was a part, were removed in mid 2016. It’s unusual for experimental wind turbines to be removed after only six or more months of testing.

In the spring of 2017, New Zealand’s Superannuation Fund, the Alberta Investment Management Corporation, and the Abu Dhabi Investment Authority wrote off their investments in Ogin as the startup ceased operations. Arpa, DOE, and the Commonwealth of Massachusetts also lost their grants backing the company.

Thus concluded the lengthiest, the most costly, and the most financially and politically connected ducted wind turbine development in the history of wind energy.

What the effort of so many talented engineers over so many years accomplished was the construction of half a dozen medium-size wind turbines with a power output typical of the late 1980s--none of which used the lobed mixer-ejector technology that was the supposed "breakthrough" of the original design.

Ogin's fate is another sad lesson in hubris and humanity's deep-seated need to believe in unicorns.


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