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Skystream Residential Wind Turbines: An Interview with Frank Greco
Sarah Rich, 6 Feb 07

greco1.jpg Now that sustainability is a relatively common concept (or at least people understand that climate change is a real threat), we frequently hear people asking, "How can I live a greener life?"

We're inundated with "simple tips" and "top ten things," but there's nothing like a strong personal incentive to bring about a lifestyle change; and there's no better incentive than money. This is a major reason for the success of small-scale alternative energy systems. For the bit of extra effort required to install an unconventional power generator on your home, you can joyfully watch your energy costs dwindle over time.

Many of these technologies -- solar and wind being the most prevalent -- have been around for decades, but only recently have they been making appearances in urban environments and on new, modern buildings. Solar panels are becoming ordinary considerations for new residential construction. And wind is not far behind. Wind has faced particular challenges that solar (PV) doesn't have: the old windmill design needed to be refined and compact enough to fit unobtrusively in a residential setting, and the engineering needed to maximize low wind speeds such that one wouldn't have to live on a Kansas plain to get the most out of their turbine.

The people at Arizona-based Southwest Wind Power believed that if design and engineering could be sufficiently streamlined, homeowners would want a turbine to power their house. They released the Skystream 3.7 about four months ago and so far so good. I spoke recently with the company's CEO, Frank Greco, about how things are looking for small-scale, residential wind.

Sarah Rich: Let's begin at the beginning. Tell me about what your company, your product and your progress.

Frank Greco: The company was founded twenty years ago by two local gentlemen in Flagstaff, David Calley and Andy Kruse. The concept of the company at that time was to design and manufacture small wind generators for the off-grid market -- meaning to supply tools for people who were off-grid or did not have access to the grid, so that they could have power for lights, radio, and other modern conveniences.

Obviously the market has evolved over time and the business phase kind of grew with it, with the effect that the design of the turbines became more and more sophisticated, aiming at increasing reliability, ease of installation and ease of operation. And that market then expanded beyond just supplying those people who did not have access to electric, but those who decided they wanted to offset their current electrical usage or find alternative ways to power their homes. Also, not just homes but sailboats, and remote drilling sites, off-shore oil platforms and so forth. So the business has evolved over its life span, primarily over the last 6 years, but with continued focus on supplying the off-grid market, which up until now has been about 95% of the business. But the changing world, as you speak of, and the need to find alternative sources, drove us to look very closely at the on-grid market. We wanted to come up with products that specifically addressed that market, as well -- one, because there was a need; and two, because obviously when you compare the off-grid to the on-grid market, the on-grid market is very much larger. So a lot of time and effort was put into developing a residential size wind turbine that people could buy much like purchasing a high-end appliance for their home, except that this would save money instead of consuming electricity. Basically, it would be a plug & play item that was architecturally pleasing to the eye, was friendly to a more residential environment as opposed to a real rural environment, and could be installed for a cost that was competitive with the retail price of electricity. You'd pretty much install and forget about it and let it run much like you would an air conditioner on your home.

So in the fall of 2006, we actually released that product. It's called Skystream 3.7 -- it is a 1.8 Kw machine which is designed to supply between 35% and 70% of an average home's electricity usage. Now that can vary based on the size of the home and the amount of equipment that is inside the home. But on average, that's what it does. In some cases it can supply more than that -- sometimes 100%; sometimes it will produce more electricity than is being consumed, and those utilities that offer net metering will take that back into the grid and turn the meter backwards.

SR: That's impressive -- so just one turbine can supply that much energy?

FG: On average yes. Of course, like I said it varies according to the size of the home.

SR: What's considered an average home size?

FG: It was based on the average size home in California.

The product was done on a development contract with the Deptartment of Energy, and the actual prototype unit has actually been running since December of 2004. We also did a Beta program in various locations throughout the US. And finally we released the product to the public in October.

SR: And it's already won an award I hear?

FG: Yes it has. We won an award previously for the design of the product from the Department of Energy over a year ago as the most innovative small wind technology available, and then more recently in Popular Science.

SR: We talk a lot about urban density on Worldchanging as a model for sustainable living. How do these function in a dense environment where homes are close together? How much space do you need?

FG: Well, to get maximum efficiency out of any wind turbine, it needs to be exposed to the wind without being blocked by the home or by trees. Of course, some of those issues can be overcome by putting up a higher tower, but the higher you go, the more expensive the overall product becomes. We basically designed it on an average tower height of 34.5ft, because at that point we felt the economics were maximized. Except for needing to overcome certain obstacles that may be indicative to a certain installation, 34.5ft would be the optimum height. As you start going higher, the increase in power you receive is not linear to the incremental increase in the cost of the tower.

As for space, right now we are recommending a half acre of land, to start. We realize that this technology is quite different from what most American homeowners are used to, so based on a half acre site, we felt it was highly likely that there would be a location on that lot which would be perfect for it. It's not something that would be visually intrusive to anybody, and certainly it would give the unit enough room to pick up the wind and produce power at its highest potential efficiency. So that's the market that we're initially targeting: a half-acre or more of land.

The product was designed to also operate in very low winds. The reason is that most people don't live in windy areas, because it's uncomfortable. So the majority of benefit comes from a wind generator that would operate and produce power at relatively low wind speed, and achieve maximum power at those low wind speeds, and operate continuously.

SR: Help us envision what kind of wind would be required to get that continuous operation.

FG: We base everything on an average wind speed of 12mph -- which is like a flag mildly waving int he wind. At that point it would produce about 425 KwH per month, which is pretty good based on that low of a wind speed. It would only take up to 20mph for the unit to run at its full capacity, where most technology requires speeds of 30mph. So it will reach full capacity, relative to other technologies, at a relatively low wind speed. Of course the number of KwH can rise dramatically at that point.

skystreamdiagram.jpg SR: And will the additional energy get stored?

FG: The Skystream will do battery charging. The system is very versatile. And I'll mention: everything required to run the system is totally enclosed inside the turbine. There's no requirement for collateral equipment. So everything -- the converter, the electronics, the controls -- everything is located inside the machine. And it does operate wirelessly. It comes with a remote monitor that tells you exactly what the system is doing, how much power you're generating, what your wind speed is, all of that. And it does that wirelessly. And as we continue to work on technology, we plan to also offer software upgrades that people can remotely program into their existing unit.

SR: What's the tower made of? What are the materials?

FG: The pole tower -- which has no guidewires and a very small footprint, it only requires about 20 sq inches of area above ground -- is made of galvanized steel. The turbine itself is made from aluminum castings and all the exterior components, as well. And all the internals of the machine -- the stationary part of the alternator, often called the windings -- are made of copper. And the internal rotating portion that creates the magnetic field that generates the electricity are permanent magnets mounted on a steel casting. And everything else is electronics.

SR: And how deep does the foundation have to go?

FG: That depends on the soil type. But a flat foundation is about 2 feet deep. A pier foundation would be about 4 feet deep. Those are based on poor soil conditions.

SR: So far, what's your average consumer like?

FG: We don't always know who the end user is. We sell through distribution systems. So in some cases the product would be sold to a distributor, and that distributor has a series of dealers or alternative energy dealers who are the ones in direct contact with the end user. So we don't always know who that is, but we are taking steps to learn that. Some of the ones that we do know would range from a typical residential homeowner in kind of a rural-urban environment, to some small farms, small businesses, schools.

And I will add that the state of Pennsylvania recently purchased 15 and placed them in different public sites around the state as a small scale wind promotion project. It came from a grant from the state, and the primary focus was on education, getting people aware of alternative energy through wind and showing that there is good technology available. This most recent show was a farm show where we actually installed a Skystream directly outside the building and it was used to power some of the needs of the show itself.

SR: It seems like most people are more likely, when they think of "alternative energy" for the home, to think of a solar panel. Do you see that shifting? Do you think wind will gain that automatic association, and gain popularity for residential purposes?

FG: Well PV is a very good technology, and PV and wind work very well together as a hybrid system. Sometimes it's sunny, sometimes not, and the sun and wind tend to counterbalance one another. So it's a good combination. What's happened is this: There hasn't been a small residential grid-tie unit in wind available with this technology until now. So it will become more and more popular. The other thing is the cost-effectiveness, and Skystream enters that market at below the average retail price of electricity. So we see it as a market that is going to grow as quickly as we've seen the PV market grow. The PV market does suffer some availability problems; they have a larger demand than they can currently supply. So I think that's a plus for wind. People can start saving money now and realize that renewable energy is a lot easier than they thought it was.

SR: I was looking at your website and I was interested in the wind power maps where you can select your area of the country and see the wind power and the incentives that are available depending on where you live. That's a great, interactive feature of your website. Can you tell me a little bit about those maps?

FG: Well the US is quite well mapped out, except for the Southern states -- the mapping system is a good indicator currently of what your average wind resource is in a particular area. This technology is continuing to be developed and we see it in the near future having the potential to expand, along the lines of Google Earth, to allow you to put in your address and zoom in remotely on the property to determine the best location and what the wind resource is. It's a good tool; it can also aid in the economic analysis of what you can expect based on your average wind speed.

SR: That's very cool. It's always great to see how new technologies can build up the efficacy of somewhat older technologies. Is there anything else you'd want people to know?

FG: Basically, just to summarize, the design of Skystream is primarily focused on the residential user as well as small businesses and public facilities, but it was designed to be easy to install, user friendly, plug & play, very quiet. I mentioned that our initial target is that half-acre or more, but as renewable energy takes more of a stronghold, not only from a cost perspective but from an environmental perspective, we expect that minimum to shrink to smaller lot sizes. It's not meant to be in the middle of a city but maybe approaching something closer to an urban environment.

SR: Is it something you could imagine, in an urban environment, being able to be on the top of an apartment building, or otherwise elevated outside of obstruction, and then to be useful for that market segment?

FG: Well it could very well be in an apartment complex. These things can be architecturally integrated into the building. But you have to be careful about placement of a wind turbine because wind tends to get distorted when it crosses over a roof line. But yes, there could be some kind of center location where there might even be multiple Skystreams supplying the power for a community; maybe not every home but certainly the public areas of the property.

In terms of condensed or spread out living, what's really interesting about distributed power is that you are essentially using the power from the source where it's produced, as opposed to having centralized power production. From, say, a coal-fired power plant, you are distributing energy at long distances via the electrical grid; whereas, what's so fascinating about distributed energy -- solar and wind -- is that you are using it at the point of source, so it's that much more efficient.


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So what are the economics of these turbines like for an average homeowner with the space to put one in?

Posted by: Dave Cutler on 6 Feb 07

Anyone with direct experience want to answer that?

Posted by: Alex Steffen on 6 Feb 07

This is an exciting development in the alternative energy market, the marketing seems good, the website is clean and the peer review and awards seems promising.

Now we just have to work on municipalities and approving authorities to sort out new rules for these structures!

Posted by: urbanmike on 7 Feb 07

To calculate the economics of installing one of these, you need to know (at least) the following:

The rated power-curve of the turbine (i.e. the power output at different wind speeds - an exponential curve)

The swept area of the blades (allows you to handle the power-curve more accurately)

Wind-speed data for your area at the height you're able to install the turbine. In the UK there is a national database that provides this (on a per square km basis - I don't know if anything comparable is available in the US. You may need to buy/rent an anemometer and measure it yourself.

Cost of surveying, installing and buying (plus any planning costs/considerations - what will your local council and neighbours think?)

Determine if you can sell any excess electricity back to your supplier (or get a discount)

Determine if you're going to always be able to use all of your produced electricity or if some (e.g. on very windy nights) will be wasted. Batteries are an option but quite expensive.

Long and the short of it is that home-based turbines can sound attractive but the devil is in the detail. You may find it's actually more economic to improve your energy efficiency or get solar panels (electricity or hot water) instead.

Posted by: John Kazer on 8 Feb 07



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