Small-Scale Wind Turbine Potential Great, Limited By Installation & Electricity Costs: New Report Finds
by Matthew McDermott, New York, NY 
on 08. 7.08
Size comparison of small-scale versus industrial scale wind turbine image: Carbon Trust
Most of the time when we talk about wind energy, the turbines referred to are of the couple-hundred feet tall behemoth variety. But it’s not just the big boys which can have a place in reducing our demand for fossil fuels. A new report from the Carbon Trust details the potential of small-scale wind turbines in the UK, how much power could be produced and how much carbon emissions could be avoided.
Setting the Scale
For the purpose of the report, the Carbon Trust classifies small-scale wind energy as any turbine rated less than 50 kW, generally intended to supply buildings and which may or not be connected to the electric grid. It is pointed out that these turbines require many of the same wind conditions which larger turbines require and are best utilized in rural areas.
That said, while larger turbines may have capacity factors of 28-35%, on average, small-scale turbines, because of their height small-scale turbines only achieve 15-20% of their rated capacity in rural areas, and only 10% in urban areas.
Cost of Turbines and Electricity Limits Installations
Theoretically, small-scale wind energy has the potential to generate 41.3 Terrawatt-Hours of electricity an save 17.8 Million tonnes of CO2 annually.
However, given installation and current electricity costs, the Carbon Trust assumes that only 10% of households can realistically install small-scale wind turbines. If this happened, up to 1.5 TWh of electricity could be generated, and 600,000 tonnes of CO2 emissions avoided.
This amount of electricity is a mere 0.4% of total UK electricity consumption.
The report goes on to note, that in urban areas roof-mounted turbines may never pay back their embedded carbon emissions.
Underutilized Potential?
The obvious thing that this study says to me is that there is great overall potential for expansion of small-scale wind energy. While it may never be able to compete with gigawatt-sized wind farms in terms of total output, there is certainly a place for this sort of technology. Certainly the visual impact of these turbines is much less than industrial-scale turbines and that alone is a plus in my book. Move the big boys offshore and expand small-scale wind in rural areas onshore.
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If you are going to talk about visual impact, you need to consider location. If you think that the visual and noise signature of small turbines is minimal, you must never have seen an installation.
To get away from the turbulent flow near a building, you need to have wind turbines mounted on a mast of significant height. This will put the turbine up where everyone can hear and see it. "building effect" for increasing wind speed id an unproven fantasy of architects and designers.
Remember that you need a site to have wind make sense. If you don't have prevailing wind speeds above 12mph consistently, you probably can't make wind work. Power is related to wind velocity^3 so even 10mph is a lot less power. Turbines have been designed with low cut in speeds to capture the lower end of the power curve, but does it really make any sense to try to do this? It is unfortunate, but putting the wind where the people are in the cities just doesn't seem to make sense most of the time.
It is good to hear that a well researched report grounded in good science, not wishful thinking, has come out on this topic.
I think with small scale items, you are more likely to get zoning issues and noise complaints. Maybe a wierd variant of NIMBY - not in my neighbor's backyard.
These turbines would definitely be a good compliment to a photo voltaic array supplying a battery bank or sending power back to the grid.
vsk
Small scale wind will only be used in niche applications, like deep in the countryside for people off the grid. The vast majority of wind power will come from industrial wind farms. The statistics in the article make this point for me. Why invest in 1000s of small turbines when you have double the efficiency and many times less maintenance costs with a few large ones? Microgeneration is a nice idea, but it's not reality. The only personal power generation I see gaining widespread use is possibly solar hot water, unless PV prices drop by a factor of 10 over the next decade. As for wind? Forget about it.
So, instead of one or two majestic, powerful, professionally engineered and installed large scale wind turbines that would power a small town (like Hull, Massachusetts), there would be a couple thousand (2-3 per home) small, inefficient, owner maintained and installed (at altitudes that are severely limited) pinwheel toys.
Then there are all the "Grid Tie" inverters that would be required at each location. Some would be new, some maybe not. The efficiency and safety of each could not match the industrial equipment that a power company installs when a large scale wind turbine is brought on-line.
I don't want to be a pessimist, but please look at "Underutilized Potential?" statement with a bit of common sense.
My friend started Mariah Power a few years ago and has made some impressive advancements (I admit some bias...). There's currently one out in front of the US Botanical Garden in DC.
Even though you can plant them in your yard and see significant savings (assuming you get decent breezes), placing them on city roofs might be better. The overall power benefit isn't huge, it won't let you live off the grid (you'd need batteries for that), but it could save you significant money each month.
The point about solar hot water is a good one, but something like the Windspire can make a difference.
And why do windmills have to generate electricity? Small windmills should be able to pump water, or run a compressor using direct mechanical energy. A cooling compressor hooked to a windmill might run a chilling unit, and voila! a block of ice for an icebox, no electricty involved.