FROM A WIND GENERATOR
Picture how you would use electricity in your home if you weren'tworried about cost, despite the fact that your neighbors pay 13.9 cents perkilowatt hour-one of the highest residential electricity rates in the nation.Now picture a luxurious home with no monthly electric bills because a windgenerator supplies all the needs of the home, with extra to sell back to thelocal utility.
We live at an elevation of 6,970 feet (2,124 m) in Sandia Park, New Mexico, ona flat, furrowed two and a half acres that was once a pinto bean field. We liveseven miles (11 km) from a mountain range called the Sandias, which is Spanishfor watermelon. At sunset the mountains take on a strange deep green and hotpink glow-one of the reasons our state is called The Land of Enchantment.
There are challenges to living in our high desert area. Temperatures swing50 degrees Fahrenheit (28°C) almost every day of the year, so heatingcosts are important to a household budget. There are also dust devils,lightning strikes, cactus, and tumbleweeds that make the outdoors inhospitable.
We do, however, have some of the best winds in the nation. These arecanyon-effect winds, funneled between the Sandia Mountains and the Manzanomountains, and down through the Tijeras canyon. After observing the weatherconditions in our area for about ten years, we were confident that a windgenerator would be profitable.
We Purchase a Used Jacobs
In 1994, we purchased a used gear-driven Jacobs Wind Energy Systems turbinethrough the want ads in our local electrical co-op's newsletter. The systemcame with two sets of 23 foot (7 m) spruce blades, an oversized 25 KVAalternator with inductive field winding (no brushes), and a 100 foot (30 m)free-standing Rohn tower. The Jacobs uses an oversized alternator to provide alonger alternator life.
The stub tower consists of a custom eight foot (2.4 m) tower segment whichhouses the 25 KVA alternator and has the 90 degree hypoid gear drive mounted ontop of it. Altogether, the stub tower weighs about 1,200 pounds (544 kg). Mostof that weight is in the hypoid gear drive. The stub tower assembly bolts tothe three flange plates on the top of the Rohn tower.
As part of the purchase agreement, we promised not to divulge our cost, buta good price for a system like ours would be US$7,000 to $13,000. The man whosold us this system was getting out of the wind generator business altogether,due to his age. He had professionally sold and installed many systems identicalto ours for thousands more than we paid. If all runs smoothly, it should payfor itself in about nine years, with a cost of about a dollar per installed,rated watt.
We made the decision to follow all rules and regulations at every governmentlevel. We even made sure we had the neighborhood's blessing. This paid offgloriously about two years into system operation. We were working in the yardand a van-load of Bernalillo County building inspectors demanded to see ourpaperwork on the spot. Our ducks were all in a row, so the inspectors droveaway. Since our permit was approved, cell phone towers have sprouted likemushrooms (some would say toadstools) in our area, giving towers a bad name.
Tim Builds the Tower
Tim assembled the tower in the back yard in his free time. Getting everythingready took about seven months, working weekends and evenings. The tower wenttogether like a giant's erector set. It lay there on its side until the day ofthe tower raising.
We put the Jacobs stub tower on the end of the Rohn tower and then used afront-end loader to prop up the stub-tower end of the assembly on a 55 gallonbarrel. With the top of the tower propped up, we were all ready to mount theblades on tower raising day.
Each trench contained 252 feet (77 m) of 5/8 inch (16 mm) rebar, and wood formsto create a 2 by 2 foot (0.6 x 0.6 m) L-shaped structure. After six yards ofconcrete had been poured into the forms of each trench, the triangular formjoining the three legs was filled. The integrity of the triangular pad isinsured by remesh (welded wire fabric). The whole foundation has about 20 yardsof concrete.
When we were all finished, the only things visible were three flange platesprotruding from a triangle-shaped concrete pad. These three flange plates wereprecisely located to mate with the three flange plates on the bottom of theassembled Rohn tower. This fit was critically important because the entireassembled tower and wind generator were to be lifted by a crane and bolted tothese flange plates after the concrete set.
We bought 1,000 feet (305 m) of #6 (13 mm2) wire, which in theory meant threeruns of about 333 feet (100 m), at least on paper. When we actually dug thetrench and laid the wire from the tower to our house, Tim pulled the wire, andthere was only about six inches (15 cm) to spare! We felt fortunate that itturned out six inches too long, instead of six inches too short.
| Jacobs Wind Genny InstallationCosts | ||
| Item | Cost (US$) | % of Total |
| 20 yards concrete | 1,157 | 25.3% |
| Architectural approval | 685 | 15.0% |
| Wire | 500 | 10.9% |
| Front-end loader rental | 450 | 9.8% |
| About 4 hours of crane rental | 400 | 8.7% |
| Miscellaneous welding | 375 | 8.2% |
| Trencher rental | 354 | 7.7% |
| PUC administration fees | 280 | 6.1% |
| Machining work | 250 | 5.5% |
| Building permit for tower | 127 | 2.8% |
| Total | $4,578 | 100.0% |
Tower Raising Day
Tapping the years of experience of the former owner, we decided to use a craneto raise the tower. We followed his recommendation to assemble the tower on theground, where we could take all the time we needed. In fact, we hired him ontower raising day to insure that everything would go smoothly. This was wellworth it, since the most expensive part of the installation was the hours ofcrane time involved.
| Local Payback Rates | |
| Month | $ per KWH |
| January | 0.0174 |
| February | 0.02586 |
| March | 0.01716 |
| April | 0.02043 |
| May | 0.02022 |
| June | 0.01807 |
| July | 0.0162 |
| August | 0.01725 |
| September | 0.03706 |
| October | 0.0342 |
| November | 0.0326 |
| December | 0.02989 |
Tim then did his first tower climb to disconnect the rigging. As he climbed,rain threatened to fall, and there was lightning in the distance. We had hearda story of a rainstorm resulting in a stuck crane and US$3,000 of rental timebefore a D-8 Caterpillar was used to tow the crane out. But as an old adagesays, "He that observeth the wind shall not sow; and he that regardeth theclouds shall not reap." So Tim climbed to the top, unhooked the cranerigging, added oil to the gearbox, and climbed back down. Rotten weather hasslowed us down, but never stopped us!
History & Service
We purchased the system in July of 1994. We were officially hooked up to thegrid on March 20, 1995. Over the past four and a half years, we have only had afew problems. The lower alternator bearing needed to be replaced once. And theelectronics have needed minor adjustments.
| April 1999 Data Summary | |
| Monthly Data | |
| Description | Data |
| Outside meter reading (Start KWH) | 95,945 |
| Outside meter reading (End KWH) | 95,577 |
| Inside meter reading (Start KWH) | 38,460 |
| Inside meter reading (End KWH) | 40,500 |
| Plains Energy purchase rate (per KWH) | $0.02043 |
| CNMEC rate (per KWH) | $0.139 |
| Tax rebate (per KWH) | $0.015 |
| Analysis | |
| Description | Data |
| Total generated (KWH) | 2,040 |
| Total sold to Plains G&T (KWH) | 368 |
| Total consumed (KWH) | 1,672 |
| Tax rebate | $ 5.52 |
| Plains owes us | $ 7.52 |
| Utility savings from wind genny | $232.41 |
| Personal use of business product | $ 34.16 |
| Total Benefit | $245.45 |
The yearly maintenance on our machine consists of greasing the zerk fittings(two on the drive shaft, two on the roller plate that the hypoid gear sits on,and one on each blade), and draining and replacing the 1.5 gallons (5.7 l) ofgear lube in the hypoid gear drive. If we hired someone to do the work, webelieve it would cost about US$150 per year, but since Tim does all themaintenance, the only cost is grease, gear lube, and Tim's time.
Noisy?
Most people are surprised at how quiet the wind generator is. It's very quietin winds up to 30 mph (13 m/s). At this speed, the centrifugally actuatedgovernor begins to feather the blades, making them less aerodynamic and muchnoisier. When the winds are above 30 mph, we're not usually outside anyway. Ourneighbors to the north have their home about 500 feet (150 m) from our windgenerator and say they usually don't even hear it. The neighbor on the otherside has told us that when he can't sleep, he likes to go outside to listen tothe soothing hum of the wind generator.
We live in an area of independent people. In our neighborhood, one manrestores Model A Fords. One woman raises exotic birds, and another breedsshar-pei dogs, so we all have an attitude of live and let live. In fact, hotair balloonists and hang gliders have used our wind generator as a landmark tonavigate by. They often land in the 80 vacant acres behind our property.
Paperwork & Contracts
It took about nine months to receive the legal permission from the federalgovernment and the Public Utilities Commission to hook our system into the gridto sell back power. This meant a back and forth letter exchange, with usfilling out many forms and exercising the authority given us by New MexicoPublic Service Commission Rule 570. We then were given a five year contractwith our local utility, Plains Generation and Transmission (Plains G&T). Weare paid a low of 1.620 cents per kilowatt-hour to a high of 3.706 cents perkilowatt-hour for the electricity we generate. We joke that the monthly paybackrate seems to be inversely proportional to the winds. If there were not so muchtruth in it, we could laugh more.
We pay a US$10 monthly fee to the Central New Mexico Electric Co-operative(CNMEC). For this fee, they are supposed to read our meter monthly, and reportthese readings to Plains G&T. Plains G&T is a separate business fromwhich CNMEC purchases all its power. When we buy electricity, we purchase itsecondhand from CNMEC. When we sell it back, our electricity goes to PlainsG&T at wholesale rates. This reporting process of our meter readings isimportant because it determines the amount we are paid for what we generate.The Co-op is also supposed to report the meter readings in an efficient, timelymanner. Although we pay our $10 monthly, their part of the agreement has neverbeen fulfilled.
For this reason, and also because of the deplorable payback rate, we quicklycame to the conclusion that the best use of our electricity was to use it upentirely. The contract forbids us from selling extra electricity to ourneighbors, but many months we produce enough to supply about four households.We still pay the fee because we believe they would disconnect us if we didn'tuphold our end of the contract.
Tim designed and installed a radiant heated floor. It heats our entire houseusing wind-generated electricity. It warms up to 90°F (32°C) in abouttwenty-five minutes. And, best of all, it can use up 100 kilowatt-hours perday.
With our heated floor, we only used our woodstove once or twice throughoutthe entire winter of 1998. We also have a forced air heating system poweredwith propane, but we do not use it much anymore. This radiant floor design isakin to standing on a beach, where the sand has been warmed by the sun-nice!
The floor is Vermont slate. Under it, cemented to the tile with mastic arequarter inch (6 mm) copper pipes set six inches (15 cm) apart and nestled inwood grooves. The foundation of the floor is a concrete slab. The copper pipesare filled with about 80 gallons (300 l) of a 60/40 water/antifreeze mixture.The fluid circulates in an integrated pattern, so there are no cold spots onthe floor. Tim buried a hot tub thermostat in the grout of the floor to act asa temperature sensor.
It is a closed system that circulates througheither an electric or a propane water heater. With a switch on the wall, we canchoose between heating the floor with electricity or propane. The propane is abackup that we seldom use.
No Need to Conserve
We put up a wind generator because Tim got bit by the wind energy bug. We hopeto be an encouragement to anyone who has a similar ambition. We like thefreedom that the wind generator represents. We're not millionaires, but we surefeel like we are. If you visit us, we'll never tell you to turn off the lightsor turn the heat down.
| Heated Floor Costs | |
| Item | Cost (US$) |
| 100 square feet of Vermont slate | $1,000 |
| Copper pipe and fittings | $500 |
| Sub-flooring (plywood & 2 x 6 lumber) | $500 |
| Propane water heater | $200 |
| Electric water heater | $150 |
| 70 gallons deionized water | $70 |
| Water heater safety tank | $60 |
| 70 gallons antifreeze | $45 |
| Hot tub temperature sensor | $35 |
| Total | $2,560 |
Written by: Home Power
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