Small Vindication: Renewable Devices Swift Ducted Rooftop Turbine Gone

By Paul Gipe

Like many other rooftop wonders in the late 2000s the Swift arrived in an embarrassing blaze of hype. And, like all the rest, it’s gone. Though it took an agonizingly long time for them to disappear.

I am writing this now to close the book on this sad little turbine and the whole “let’s put them on the roof” phenomenon. Stumbling across an obscure NREL field test report from long ago (see Power Performance Test Report for the SWIFT Wind Turbine) dredged up this dark period in small wind turbine development.

For me the whole episode is epitomized by a full-page photo of several Swift turbines on a rooftop in a 2007 architectural magazine. The photo illustrated a feature article on the coming of rooftop wind turbines and how they would revolutionize renewable energy in urban areas. It was telling then that the Swift turbines in the foreground were tied off. Yes, they were tied off so they wouldn’t turn. The irony of this was lost on the magazine, its readers, the promoters, and the British government that was throwing money at the things. It was also a slap in the face of those who had spent decades convincing anyone who would listen that wind energy really does work.

Renewable Devices Swift Turbines—that’s its full corporate description–claimed that the 2.1 meter-diameter ducted turbine, including its shroud, was rated at 1.5 kW at a wind speed of 12.5 m/s. The company also claimed that the turbine would generate “2,000 to 3,000 kWh per year” mounted on a rooftop. Worse, their product literature said the turbine would generate “up to 3,000 kWh per year” of course with a footnote in small print that it depended upon the “siting” of the turbine–this for a wind turbine that was designed and promoted to be used on rooftops in urban Britain. (That should ring alarm bells if you know anything about wind energy.)

Thus, the company was deliberately vague on how much electricity its turbine would actually produce. That didn’t stop them from implying that it “could” generate “up to 3,000 kWh.” Consumers would naturally gravitate to the 3,000 kWh and not to any qualifiyers.

I and others (Hugh Piggott for one) questioned this at the time (see Roof Top Over the Top in Britain) and the company responded aggressively to anyone challenging its technical credentials. The inventor/designer, David Anderson, may have had a PhD as he used Dr. before his name. He liked to wave that in front of us hoi polloi who had the gall to question his competence and integrity.

In mid 2006 I had a series of heated exchanges with Renewable Devices’ Dr. Anderson. He tried a crude form of intimidation and I responded (see Response by Paul Gipe to Dr. David Anderson Renewable Devices Swift Turbines) with a warning of my own.

So after I saw the NREL report on the Swift turbine, I pulled out a product brochure from 2006—yes, a decade ago. I then looked up their web site for any more specs. Even as late as 2014 the company didn’t provide any more details on expected performance than in that 2006 brochure. And this was long after the NREL report in 2011.

Of course the web site prominently includes a picture of a smiling Prince Charles giving the company some kind of insignificant award. No doubt the prince was pleased that Britain could use these tiny little things on rooftops and avoid deploying those real wind turbines across the countryside that he railed against. The prince does not like wind turbines, at least real ones anyway, and that should be a tip off that this turbine was headed for the scrap heap of history.

My unpleasant experience with Renewable Devices didn’t end with that exchange of emails with Dr. David Anderson.

In the winter of 2008 I was asked by the staff of the Michigan Public Service Commission to give a talk in Grand Rapids. The venue was Cascade Engineering, a local manufacturer of parts for the auto industry. Ok, that’s not a problem. There’s always a need for a venue. However, there was a slight wrinkle.

Cascade contacted me and asked if they could pick me up early for a lunch with Cascade executives before my program. Ok, one needs lunch I thought.

When I arrived I found that the “lunch” was an opportunity to pick my brain—for free. They had an “inventor” in the room and a model of the Swift wind turbine as well. Cascade was not paying me. They were only providing a venue and lunch. I felt ambushed by having to confront an “inventor” over lunch. He left deeply disappointed and I had a lousy lunch.

After dispensing with the “inventor,” Cascade’s executives asked me what I thought of the Swift. They obviously were up to something and had probably read or heard about my criticism of the product. I proceeded to list my concerns and just as I feared they announced that they had licensed the turbine for the US market. Why they were asking my opinion after they signed a licensing agreement is anyone’s guess.

I told them what they needed to do to win over critics, including me, and they made all the glowing promises one hears about new products. They would keep informed of their tests, yada, yada, yada.

I was not a happy camper. I didn’t care for the British management’s attempt at intimidation and I didn’t care for being ambushed by an American manufacturer to provide free consulting services to a company dead set on marketing a rooftop miracle. The business model was wrong. The turbine was wrong. The last thing we needed was another inoperative wind turbine strapped to someone’s rooftop.

Cascade subsequently installed several of the Swift turbines in western Michigan—and that was it. No reports of performance, no data, nothing despite Cascades assurances that their “testing” would be made public.

Years later I found that Cascade had quietly dropped the Swift and moved onto real medium-size wind turbines such as Northern Powers NPS 100.

Renewable Devices founder David Anderson received a US patent on the Swift ducted turbine in mid-2009.

As of March 2011 the Swift was still not certified under Britain’s MCS system, though Renewable Devices were promising that the certification was “in process.”

The field tests at NREL were conducted from April to June 2011 at the request of the company’s US licensee, Cascade Engineering.

Renewable Devices moved into another building in late 2012. Then poof, there was not another word until Renewable Devices Swift Turbines was involuntarily dissolved 12 June 2014.

I am surprised it lasted as long as it did. I have no idea how many Swift turbines were installed—and how many of them are still standing silently—inoperative–on rooftops around the world.

In 2008 I wrote (see Renewable Devices Swift Mk II AEO)

“Cascade claims on its web site that the Swift Mark II will generate 2,000 kWh/year.

Can it do so?”

Yes, but at sites unlikely to be found in Michigan at heights where the turbine is likely to be installed.”

The Swift is a 2.1 m diameter wind turbine that sweeps about 3.5 m². A wind turbine of this size requires an average annual wind speed of about 7 m/s at hub height to generate 2,000 kWh/year. Sites this windy are rare in Michigan, especially at the rooftop heights that this turbine is intended to be used.”

Should I have cut them some slack back then? Was I too hard on them? Were my concerns about their inflated numbers warranted?According to NREL’s tests, the turbine reached its 1.25 kW at 12.5 m/s, not far off from the advertised 1.5 kW in the brochure I have from 2006. However, the web site is still up and it says 12 m/s is the rated speed. If that’s the case the turbine reached 1.14 kW or 24% less than advertised. In either case, that’s not bad as far as small turbines go. The turbine’s performance was about par.

Nevertheless, it would take an average wind speed of more than 6 m/s to produce 2,000 kWh per year and more than 7 m/s to generate 3,000 kWh per year. These are not wind speeds found at rooftop, and certainly not in urban areas. These are wind speeds that might be found on a well-exposed tall tower in the Orkney’s or on the west coast of Scotland.

The Warwick wind trials found that most small wind turbine installed on rooftops in urban areas encountered wind speeds of less than 3 m/s, a few well exposed installations had from 3 m/s to 5 m/s. The Swift at the better sites with 5 m/s could produce nearly 1,000 kWh per year. Among the 26 installations tested only one had a wind speed greater than 6 m/s. The Swift could possibly generate about 2,000 kWh at this site, but certainly not 3,000 kWh per year.

Thus, the Swift, when installed on a rooftop at the most exposed location in the British tests, could not generate the 3,000 kWh the company promoted.

As I wrote—correctly—in 2008 and earlier, the Swift could possibly produce what Cascade Engineering claimed at the time—at only the very best sites, but the turbine could not meet the more outlandish claims of the British manufacturer.