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News & Articles on Household-Size (Small) Wind Turbines

July 8, 2013
Paul Gipe

Wind Cube Squarely Over the Top (Now Re-Branded as Wind Sphere)

Update: Wind Cube has been re-branded Wind Sphere and their web site was active as late as 2012. And though the web site uses the name "Wind Sphere" the URL lists the product as "wind cube".

The wind sphere is a more conventional ducted (DAWT) wind turbine design in contrast to the previous square "wind cube".

The rotor on the "35 kW" wind sphere is 10 meters in diameter. Thus, it sweeps 80 square meters. A conventional wind turbine of this size is rated anywhere from 15 kW to 25 kW.

Better yet is the cost. The turbine now costs from $150,000 to $225,000. Let's say $200,000. If the turbines is conservatively rated at 20 kW, that would give us a installed capacity cost of $10,000 per kW. Small wind turbines today cost around $5,000 per kW and commercial turbines are half that.

Despite these numbers, Wind Sphere says the "product" can pay for itself after only 3 years using generous Federal subsidies.

The promoters also suggest applying for LEED (Leadership in Energy and Environmental Design) points using their product. They claim architects can get up to 7 points toward LEED ratings--another example how the LEED rating system is being abused by questionable rooftop wind projects. 

Update April 5, 2011: See WindCube: A $289,000 Scam? by Physics professor Ed Caner at Case Western Reserve in Cleveland, Ohio.

Updated June 7, 2010 with the knowledge that the article in question was "placed" by the company.

October 20, 2009

What with the flood of new "internet wonders" overwhelming me, I've decided to stop trying to debunk them all. It's humanly impossible to keep up with the things. They're like weeds sprouting wherever you turn.

So I've decided to only respond if the idea is so over the top it demands a debunking or if friends might be led onto the rocks by the sirens singing the praises of the latest "invention".

Wind Cube is one I've ignored--until now.

In their misplaced enthusiasm for supporting any and all renewable technology--especially if it's home grown--my friends at Green Energy Ohio (GEO) have gone gaga over Wind Cube.

Credible organizations like GEO do the industry no favors by covering such "products", and I use the term loosely, in their house publications. It is best if GEO and other renewable energy advocates expose these products to the daylight by critical analysis or at least leave them hidden in the shadows where they belong.

It's even more damaging when respected publications use promotional material from such companies directly.

Unfortunately, the latest issue of GEO's newsletter features an uncritical introduction to the Wind Cube at the Crown Battery Manufacturing Company in Port Clinton, Ohio. The marketing piece placed by the company intself unwittingly includes a number of damning details. The shroud on the 60 kW, $279,000 wind turbine is 22 feet by 22 feet and it costs $100,000 to install the turbine.

Let's go over them one by one and if this sounds a lot like my other posts on similar "inventions" that's because it is. The principles of wind energy don't change with the invention.

It's Nothing New

To begin, the Wind Cube is nothing new. It is a slight variation on a garden-variety shrouded wind turbine. The shroud, or funnel if you like, is a square, and thus the "innovation" and the name Wind Cube. Most shrouds are circular, but a square shroud is still a shroud.

It's Hugely Overrated

It is the shroud that intercepts or captures the wind and it the area intercepted by the shroud that determines how much energy the wind turbine can convert in to electricity.

GEO reports that the shroud on the unit at Crown Battery is 22 feet by 22 feet or 6.7 m by 6.7 m. Thus, the wind turbine's shroud intercepts 45 m² .

At a standard power rating of 200 W/m², this wind turbine would responsibly be rated at 9 kW. Let's give them 10 kW.

Off the bat, we can say that the turbine is rated at six times more than it should be: 60 kW instead of 10 kW.

It's Better than Betz

The Wind Cube is rated at 12 m/s. According to Betz, at this wind speed for a shroud of 45 m², the maximum theoretical power in the wind is 28 kW. Thus, the manufacturer of the Wind Cube says it will produce twice the Betz limit. Wow. The Wind Cube is one heck of a wind turbine, something to behold, indeed.

It's Enormously Expensive

The Wind Cube, according to the company's marketing director Stephanie Cironi, will cost $379,000 installed. Ouch!

If we use the designated power rating of the Wind Cube, the relative cost is $6,000/kW. This is about three times the cost of commercial wind turbines today. That should be a tip off that the "manufacturer" is not be being square with us.

If we use the standard power rating again, the Wind Cube will cost $42,000/kW. Yes, you read that right. If the Wind Cube had a rational power rating, the relative cost is nearly $40,000/kW or 20 times that of a commercial turbine today.

Let's cut them some slack and compare the relative cost of the intercept area. The relative cost of the Wind Cube is $8,000/m². The cost of a commercial turbine today is about $1,000/m². According to a swept area analysis, the Wind Cube is "only" eight times the cost of a commercial wind turbine today.

I should note, should it not be obvious, that a commercial wind turbine is a proven piece of hardware that will generate real electricity of a known amount. The Wind Cube is anything but a proven wind turbine.

The Wind Cube is Squarely Over the Top

The Wind Cube joins my infamous list of Inventions & Questionable Wind Turbines. While not the worst I've seen (MagWind still tops the list), Wind Cube is certainly giving the other questionable claims stiff competition.

To summarize, the Wind Cube's capacity is severely overrated and it is enormously expensive.

Most alarming is Wind Cube's claim that it can produce more energy than theoretically available in the wind. That alone should be the kiss of death. Alas, that may not be the end of it.

US federal subsidies are based on the installed cost. Outlandish and overpriced turbines, such as Wind Cube, qualify for the subsidy whether they work or not. In the case of Wind Cube, the federal subsidy is about $100,000. One could argue that the Wind Cube is not a wind turbine, but a tax turbine. It's enormously inflated cost could be driven by the desire to maximize tax benefits and not wind energy.

Note: If you don't understand any of the above, you need to pick up any good book on wind energy and work through the numbers. And don't let talk of Bernoulli fool you. The poor guy is no doubt turning over in his grave.

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