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CARBON NEUTRAL STUDIO
Harvesting sun and wind energy at the Manse.
Our goal is to become 100% energy independent and the sooner the better. Heat, electricity and food were our starting point, and we’ll soon move on to transportation and cooking.
Heating:
We have renovated and insulated the “Ell”, the series of rooms off the back of our house. Our plan is to live in these rooms in the coldest months, much as in the 1700’s, the home’s original occupants must have hunkered down, using the downstairs rooms in the winter. We started with a “passive solar slab” which is an 8” thick slab of concrete that is actually floating in a bowl of insulation. There are two inches of insulation below the slab and four inches separating it from the foundation. Sunlight coming in the windows in the winter heats up this slab each day, and that heat is released back into the room at night. The overall fluctuation is about 8 degrees, starting at about 68 in the morning and heating up to 76 in the afternoon. We get about 35 “Heating Degree Days” of solar gain on a sunny day. So, if it’s 35 outside, it’s 70 inside. When it gets down to about 25 outside, we start a fire in the external wood stove which uses about 12 cords of wood to heat the house and the studio and wood shop in the barn. Burning wood releases the same amount of CO2 as rotting wood, so it is really a carbon neutral process. We do not need to cut live trees for firewood as any good dead dry wood burns well in the stove. People even drop off pine that they would have had to burn just to get rid of. In the future we plan to add some active solar hot water to reduce the use of the wood stove even further.
Wind:
The Eoltec wind machine has an 18 foot wingspan and is mounted on a tilt up 106 foot tower. The 5 bases are 6’ x 6’ and are 8 feet deep, using 40 yards of concrete to hold the tower in place. It was installed by PV Squared (413-772-8787) of Greenfield at a cost of $36,000. We received a grant from the Massachusetts Technology Collaborative for $12,000. You can learn more about them at www.masstech.org . We have generated 3556 KW hours of electricity in the past year, eliminating over two tons of CO2. One kilo watt (KW) is one thousand watts, so one KW hour is the equivalent of 10 100-watt bulbs burning for one hour. There is very little maintenance required, we expect to lower the wind generator once every two years to check on it. Its life expectancy is 30 years. Due to the quality of the wind, meaning the fact that it is not a steady velocity and direction like it would be at the beach, or up higher, the windmill is producing about 60% of the energy that we estimated from wind maps (average, 11mph). At the current cost of power, the windmill should pay for itself in about 18 years, but we are fairly confident that prices will rise dramatically, reducing the payback time. The Eoltec has a variable pitch prop which makes it spin at a constant velocity and expands the range of wind speeds at which it makes power. It starts spinning at 3 meters per second, reaches full output at 12 MPS and continues to make power at any higher wind speed. The electronics that connect the power to our house and the grid consist of a wind interface, which is a bank of capacitors that store and convert the “Wild AC” to usable DC current. The “Power One” inverter converts the steady DC to Alternating Current that matches that of the power grid. This keeps the power matching our system so there are no fluctuations. It also must shut down the power in the event of the grid going down so that people working on the power lines are not electrocuted from the “dead” end of the electric lines. The power goes through a standard power meter like the one on most people’s homes to keep track of the power created, and then goes right into a sub panel on our electrical system in the house. Where our old meter was, there is a “Net Meter” which reads the energy going both directions, so if we are making more power than we are using, our meter spins backwards, giving us a credit on our account. The advantage of having a “Grid tied” system is that we can use all of the power that the windmill generates, sending the power out to our neighbors if we are not using the power. In a battery powered or independent system, once the batteries are charged, the power from the windmill is wasted. Our electric bills are now down to about 25 dollars a month, and at some point soon we will install some photovoltaic panels on the barn roof to augment our power production, especially for the summer months when the wind dies down.
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