Saturday, July 26, 2008

Advice on household wind turbines in Maine

Advice distilled from consults on local wind turbine projects, and from our friends at NRG Systems, Inc.:

Most folks think about getting a wind turbine to make "greenbacks" and to be "green." A minority need one becuase they lack grid-based electricity service. But put a turbine in the wrong spot, and you will lose money and waste precious resources: neither greenbacks, nor green! And even an off-grid turbine can be outperformed dollar for dollar by solar panels if it is in the wrong place.

(I'm starting a photo-collection of "turbines in the wrong place," for the edification of our students, who can learn from other's mistakes.)

First decide what it is you are trying to achieve. Be deadpan honest. Are you really worried about energy bills, or do you just want to be "green?" Or is it that you'd like to be free of foreign oil? All are legitimate reasons, and certainly, I can't help you much with figuring out your motives. But it helps me advise you if you've actually figured them out as honestly as you can.

If you just want to be green, and are not at all motivated by saving money, I can't help much there either because there's no analysis to be done. Go buy whatever turbine you like, and good luck to you.

If you want primarily to save money, and being green is a secondary motive, start with an overall household energy assessment, not a wind assessment. Before you decide to spring for several thousand dollars of turbine, you would like to know if you could save more money by putting the same investment into insulation, windows and doors, new bio-mass or other green fuel heating systems, or new appliances. I recommend the Lawrence Berkeley Laboratory's Home Energy Saver, an online audit program. Better yet, hire a professional energy auditor. Be sure to pick lower hanging energy fruit before you spring for that wind turbine. These fruit can be surprising "rich." Say you're running an outdated 1970s fridge, at perhaps 800 watts per hour, 24/7. Replacing it with an EPA Energy Star-rated 300WH fridge for $1,000 will save you 24 times 500 watts per day, or 12KWH. That's far more watts per day than you'll get out of a 1KWH turbine for much the same money, since the wind doesn't blow every day! The fridge is a far better investment than the turbine.

So go figure, literally. You probably have some wasteful appliances that will save you more moolah than a fancy new turbine. I recommend the "Kill-a-watt" meter, which you can buy online, to help you measure the energy performance of your plug-in appliances. For wired-in devices, just turn it on and go watch your meter turn to get an idea of energy usage. Read the dial on the meter in watts and kilowatts. Be sure to turn it off when you're done!

Once you have logically eliminated all more cost-efficient energy savings, it's possible you might benefit financially from a wind turbine. How do you figure this out? Well, first you need to know if you have a viable site. In general, you need average wind speeds of more than 10 mph to make reasonable quantities of power from the new generation of turbines, and you would prefer to have even more wind than that to get the best return on your investment. Although some models are advertised as producing power at wind speeds as low as 7mph, there's not much point putting a $15,000 turbine on a 7mph site if a 15mph one is available.

In Maine, these higher average wind speeds are common on ridges and on the coast. Sites open to the southwest, northeast and northwest are best. If you are in a valley, you probably don't have the wind. Even if you do have a good site, you have to get your turbine well above the interference of trees and buildings: "ground clutter," you might call it. I generally recommend quite high towers for woodsy sites.

Looking at the features of your site, and having lived there for a while all help, but you're still guessing. There are two ways to determine scientifically whether your site is viable. One is to put up a wind turbine and see how it does, recording the production data. The other is to put up wind assessment equipment for a year, and record the wind speed and direction data. If you decide you want a small scale turbine, on the order of 1-5 KWH, probably $1,000-$5,000 and you have the money, it may be cheaper to simply put up a turbine and see how well it works than to do a wind assessment first.

If you want a larger turbine, above 5KWH or so, I would recommend collecting a year's data before investing in a turbine. Equipment for measuring the wind is expensive too, but various firms provide the equipment. Other firms erect the assessment towers and collect the data for you.

At Unity College we do wind assessment for community wind projects (not commercial ones) using equipment provided by NRG Systems incorporated, a sponsor of the college and the market share leader and standard-setter. This allows us to train students in the use of the equipment, and more importantly in the science, engineering, economics, policy and math associated with the wind power industry. Current projects include the community wind assessment site at Mount View High School in Waldo County, Maine, and a project to make a household scale wind assessment tower for smaller turbine installations.

Photographed here are students working on the Mount View project.

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