Doc Sydnor has had a full career in neuro-opthalmology and a lifetime of ranching cattle. He raises his own line of Red Devon cows on grass in the Cane Creek Mountains of the Piedmont region of North Carolina. You can find fine cuts of his Braeburn Farm beef in local restaurants, farmers and cooperative markets, at the local butcher and at a store on the farm. Cindy Sydnor offers training in dressage at the farm. Doc has been discussing renewable energy possibilities at Braeburn Farm with Christopher Carter for about a decade.
It seems that the Sydnor family is situated on an ideal site for small wind power generation. On the hill above their ranch house rises one of the highest peaks in Alamance County. The Cane Creek Mountains are ancient Piedmont hills that have been worn down by erosion over geologic time scales. A series of peaks forms a ridge-line dotted with communications towers and the Three College Observatory. These mountains reach elevations of just under 1,000 feet above sea level, which makes one think about winking as one says “mountains”. Rising as they do above an open plain to the west, they effectively intercept the prevailing winds and the frequent gusts that come with regular changes in the weather, especially cold fronts. In places the terrain here is rugged and steep, offering splendid views and forming headwaters of creeks that flow past former gristmills and into the Haw River.
Nearly one year ago, the Handy Village Institute hosted Dan Bartmann, author of Homebrew Wind Power, for a workshop about building small, made-from-scratch wind turbines to generate electricity. Doc sponsored Braeburn Farm’s operations manager, Nick Harper, who with six other workshop participants worked on three small turbines. They hand wound coils for the stators, cast magnets for the rotors, carved wooden blades, and assembled steel armatures for mounts and tails.
Nick and Doc brought the one of these back to the farm. This turbine is twelve feet in diameter and its copper wire coils were sized and wound to produce 48 volts. After fabrication and assembly, the turbine mount and tail were disassembled and powder-coated a dark green color chosen by Cindy Sydnor, then reassembled with the stator, rotor, and blades, and placed on a short stand where it has been on display during farm tours and community potlucks during the past year. Nick Harper cut out and painted a wooden tail with the Braeburn Farm logo.
Nick Harper and Christopher Carter demonstrate how this small wind turbine has been designed and built to “furl” out the way of strong winds, to protect itself from potential damage.
Even with a good wind resource for power generation, the best flavor of wind will be found above ground level. This is because trees and structures add turbulence to the flow of air, and the best, most efficient transfer of power from the moving air to the turning blades will take place in the smoother, laminar flow of air away from the surface interference. Thus, a turbine needs a tower, and this week, the footings for a small tower at Braeburn Farm have been laid out, dug, and poured.
During his many years installing small, stand-alone renewable energy systems for farms and homesteads, Carter has had a handful of opportunities to place wind turbines on towers near mountaintops in the Piedmont and Appalachian regions. He has installed turbines on Pickards Mountain, near Chapel Hill, Chestnut Mountain, near Mount Mitchell, and for an Inupiak Tribe in Ambler, Alaska. Today, he says he is excited to be “planting the flag of renewable energy on another North Carolina mountain.”
Walking the site with the owner and operator at Braeburn Farm, making careful observations and taking precise measurements, Carter assisted with planning for their tower installation. First came the reconnaissance and string work. Decisions needed to be made for the exact footprint of this new structure on the landscape, taking into account the slope, the relationship to existing vegetation and structures, as well as the animals. An 84-foot tower is being shipped from Lake Michigan Wind & Sun in Sturgeon Bay, Wisconsin, and the parts for its footings have already arrived. Careful drawings and calculations dictated where on the ground holes needed to be dug and at which angles the base and each anchor for the guy cables needed to be placed.
This turbine will be mounted atop a tilt-up tower, and will be raised and lowered by driving a heavy tractor away from or towards it. Make an “L” with your thumb and forefinger. Your forefinger represents the tower, and your thumb represents what is called the “gin pole”. The turbine is attached at the tip of your forefinger the tractor is attached at the tip of your thumb. Point away from yourself with your forefinger, and then pull down on your thumb with your other hand. Your forefinger goes up. Ancient Greeks developed this means of lifting heavy objects, a forerunner to the modern crane.
Digging the holes for the anchor footings, building and installing the forms for the concrete, fitting the anchors and the holes with rebar, and pouring the concrete into the forms all happened very quickly last week. In his younger days, Carter liked to dig his own holes, but was agreeable to working with a team that included a backhoe operator and a couple of trusty shovel hands assisting with the fine work.
James and Sarah pitch in on the fine work of shaping holes for the tower footings at Braeburn Farm.
Doc and Carter during filling of the tower base hole with concrete during yesterday's pour.
Yesterday, the team removed the strings and batter boards to make room for the concrete truck to drive up the hill and access the holes. Carter was a little concerned about the cold and rainy weather, and twice during the day it briefly sleeted, but it wasn’t too muddy or slippery, and the truck arrived, made it successfully up the hill, and quickly filled the five anchor holes. This required a total of 6.5 cubic yards of concrete, which he described as “5-inch slump”. This tells you how wet the consistency is, and the wetter the concrete, the bigger the slump. They thoroughly enjoyed the driver’s stories of visiting schools with his rig, and especially about his visit to a school for blind children, who experienced his vehicle through sound, smell, and touch. He would lift them up to let them feel the rotating drum.
Today, Carter is pulling up the tarps he placed on the fresh concrete to protect it from the cold and rain, taking the forms off the anchors and rounding the corners of the concrete, a bit of a signature for his brand of renewable energy performance art. He expects it will be straightforward to clean up the site with the tractor, moving some of the spoil dirt to fill in any spaces left in the holes.
One remaining concern is the cows, which need to be kept away from the anchors while the concrete is hardening, and which potentially could be harmed by ingesting any stray hardware. A couple of weeks ago, some cows found their way into the hay barn, causing some minor damage, and it is clearly not safe to leave a turbine sitting on the ground with cows around. Plans are to install an electric fence with a solar charger around the tower to keep the cows out and protect the tower from them.
Next steps include setting up a way to monitor the performance of the turbine, assembling the tower, and raising the turbine on the tower, and ultimately, interfacing the wind turbine electricity generation with the utility. Braeburn Farm is a member of the Randolph Electric Corporation, a cooperative that is interested in studying their project and working with them on a scheme for pricing that adjusts for their power generation during peak periods. The Handy Village Institute will host the wind turbine workshop again March 20-25, 2017.