Tuesday, August 26, 2008

Residential Wind Generators

Hello dear Reader!

Here's another blog entry from the category of "questions answered in an eMail"

>What do you know about residential windmills?

Here’s what I know about residential windmills:
  • …that in Minnesota any energy produced by the generator that you don’t need can be fed back into the electrical grid, basically turning your meter backwards, i.e., you will earn the residential rate per kilowatt hour (kWh) of energy
  • …that the current electrical rates of about 10 cents per kWh are going up at a rate of 10% each year, basically doubling in price every 7-8 years.

  • …that a small generator (1kW Bergey, like mine) costs about $6-$8,000 to install, but will only produce about 2-5 kWh a day (i.e., the equivalent of 20-50 cents/day or $75-185 a year at the current electrical rates).
  • …that a larger generator (10kw Bergey) costs about $45,000 to install, and will produce about 20-65 kWh a day (i.e., the equivalent of $60 to $200 a month or $750 - $2,400 a year at the current rates)
  • ...that based on where I think I know you live, you have a wind potential of about 3-4 kWh/day with the small one and 35-50 kWh with the bigger one.

  • …that Garwin McNeilus in Dodge Center has had plans to design, construct, and sell 10k, 20k and 40k residential generators for $10k, $20k, and $40k, respectively, but has not gotten anywhere.

  • …that your best bet to do something for the environment is to spend some money on S.M.A.R.T. conservation (specific, measurable, attainable, relevant, and technology-driven). To make my house work, I first reduced my electrical usage from 30 kWh a day to 30 kWh per week – a reduction by almost 85%.
    If you’d like to learn more, check out my fledgling consulting company at http://consulting.lichtnstein.org

  • …that if your goal is self-sustainability, they work best in a hybrid system using photovoltaic (PV) cells and a wind generator.

  • …that they are beautiful to look at:

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Saturday, August 16, 2008

Frequently Asked Questions

Here is an interesting set of in-depth questions that I answered for a couple from Missouri that had heard about my house from one of their relatives:

>Is there a basement and what is it used for? Is it just to store the plastic water storage tanks?
Yes, the house has a full basement with 1,000 sq. ft. dedicated to living space and the rest to more utilitarian uses. The basement has three heated (radiant in-floor heat) rooms: a bedroom, a (future) home theater, and a (future) "studio" (a room with six walls of concrete). There is also a large storage space hallway. Other rooms are a "garden tools" room, a toilet/shower and utility sink, the utility room for the batteries, the on-demand water heater, the air-to-air exchanger, the hot water storage and the radiant in-floor heating manifold. The last room is the cistern room with the three 2,500 gal cisterns. The garden tools room has a walkout to the west, as does the utility room (with a double-wide door to allow for a skid steer or forklift to be driven in for replacement of the 2,000 pound battery (Twelve 166 pound cells).

>You said in your PowerPoint on the web that you used radiant floor heat. Is that connected to the masonry stove in any way?
Yes, once I have everything hooked up the radiant-floor heat will receive its heat from two sources: solar hot water panels on the roof (I already have the panels but haven't installed them) and two 1" heat exchanger pipes in the upper third of the masonry stove. That means I'll be able to take the heat of a fire the night before to heat up my bathroom the next morning using the radiant in-floor heat installed in the bathrooms. I can also take this heat to heat my basement, e.g., the home theater room.

>Can I assume that your floor is made of plywood, etc. and not concrete?
Actually to make the Passive Solar Design work, I needed a substantial amount of thermal mass on the main floor. So I have a poured-in-place concrete floor that has a total thickness of 16" with insulation. The concrete is 4" thick (with the radiant in-floor heating pipes embedded at the bottom of the 4" though in retrospect I should have spent some time trying to figure out how to lift them up a couple of inches so that they would float in the middle, since I fear that the latency (the time it takes from turning on the heat to actually reaching the desired temperature) will be quite high, but I haven't hooked everything up yet, so this concern is at this point just theoretical. The sub-floor for the half 2nd story is double-layered plywood - double-layered, so it accomodates the thin layer of gipkrete that I poured in the bathrooms for the radiant infloor heating, and I didn't want to have any uneven surfaces.

>Does the wind turbine require much maintenance?
No, the wind turbine does not require much maintenance and if I remember correctly an inspection is only required every five years. It's a tilt up tower, so it's not too complicated to do.

>How did you determine where to place the turbine?
The rule of thumb is that you don't want to have any trees or other obstructions higher than 30 feet below the wind turbine within 500 feet of the tower. The downside is that the further you place the turbine from the battery, the thicker (and more expensive) the electrical cable neeeds to be. I used a quite thick 1/0 aluminum cable for about $650 to run the 450 feet from the battery to the top of the tower. Basically I positioned the wind generator as far away and as highly elevated as possible. I went with an 84-foot tower since the 104-foot tower would have required me to get a conditional use permit for $400 and a hearing, but in general the higher you can go, the more favorable the wind conditions (and fewer turbulences). >Do you have a solar collector somewhere, because we could not see one on the roof, tho we couldn't see the roof on the north side of the house. I currently have no solar collectors installed (neither solar hot water nor photovoltaic electric) but everything is set up for it - I have the pipes already on the roof for the solar hot water and I have a cable in the ground for the photovoltaic panels.

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