Working the land takes hard work when you consider how environmentally sensitive the pair run the operation. Thirteen Mile is certified as organic by the Montana Department of Agriculture. As a result, the flock of 300 sheep graze on grass, clover and alfalfa free of chemical fertilizers and herbicides. Organic barley with no antibiotics or hormone supplements rounds out the diet.
The ranch is also certified as “predator friendly” since Becky and Dave don't use lethal means against coyotes, bears, wolves, foxes and mountain lions that wouldn't mind eating an organic lamb or two. Besides their own vigilance, Becky and Dave use a surprising choice of animal to protect the flock - llamas. They may look docile in the zoo, but llamas are sensitive to intruders and become very aggressive to threats. Plus, the sight of a llama in Montana must be a confusing sight to a coyote.
After a crewcut, the sheep do their part to produce the company's line of wool products. Since 2004, Thirteen Mile has been processing its own wool as well as wool sent in by other ranchers - washing, drying, carding, spinning and felting the wool in a hoof-to-yarn operation. Custom machines that were built or modified to Becky and Dave's specifications were smoothly humming away on the day I visited. Two gals were proudly carrying out bags of yarn when I arrived.
Solar Scouring PowerMy original interest in this trip had to do with the mechanical system that was built to provide 500 gallons of 180-degree F hot water per day for the important wool-washing process.
Scouring the sheared wool is the most important part of the process. As you can imagine, wool starts out dirty. The trick is to clean the wool, but without too much agitation that could damage the fiber. The bottom line is, the cleaner the fibers are to begin with, the better a sweater will be. How did Dave and Becky choose to produce the hot water they needed on the organic sheep ranch? With abundant Montana sunshine, of course!
Radiant Engineering Inc. of Bozeman, Mt. (www.radiantengineering.com), was chosen to handle the project based on its engineering background and experience with renewable energy applications as well as its ability to custom fabricate the entire system.
The solar system is a closed loop pressurized drain-back type with the solar collectors serving a copper grid heat exchanger, placed in the bottom of the storage tank. An array of eight Sun Earth, 4-feet x 10-feet solar collectors were assembled and placed onto the barn's roof with the help of a crane. The pressurized drain-back tank and the open, unpressurized, 700-gallon, insulated hot water storage tank were custom-fabricated of stainless steel. Fitting and component placements in the design of the tanks were evaluated and specified with the help of 3D Microstation CAD models.
Working closely with Becky and Dave's ideas, Radiant Engineering also designed and built a unique, air-powered wool-washing system. The process involves bubbling air through wool immersed in baskets in very hot wash water contained in another custom, 275-gallon, stainless-steel wash tank.
The wash tank contains an aerator consisting of stainless-steel piping used to inflate specially perforated, epdm rubber bladders in the tank. Thousands of micro-bubbles are created in the tank, which remove the substantial filth contaminating a thick wool fleece, but without agitating the wool too much. A high-pressure blower located in the attic above the wash tank provides the air to bubble the wash water. The amount of air can be regulated to gently, but thoroughly, clean the wool.
To start the wash process, as much as 200 gallons of solar-heated water from the top of the storage tank is pumped into the wash tank. A solenoid valve opens to allow the well system to refill the tank with cold water only after the wash tank has been filled. The cold refill water is introduced at the very bottom of the tank through a distribution tube so that it layers in the bottom of the tank, immersing the solar heat exchanger.
The tanks are fitted with clever, adjustable, custom-built float switches that signal the controls to keep the various tanks at the proper fill levels. That takes the guesswork out of filling the wash tank and refilling the solar tank, a procedure that all happens automatically at the push of one button. The system provides two washes - as much as 500 gallons a day - of solar-heated wash water. The fill volume of the solar storage tank can be adjusted to allow the system to produce elevated water temperatures.
Boiler BackupTo provide heated wash water on cloudy days and to heat solar preheated water to wash temperature, the Radiant Engineering team built a backup boiler system into the project. A propane-fired Viessmann Vitodens 200 wall-hung boiler was chosen as much for space saving and sealed combustion as for fuel efficiency and high reliability.
The Vitodens serves a copper grid heat exchanger that is built into the wash tank. When the wash tank is full, its temperature is regulated by a tekmar 150 set-point control that operates the boiler to heat the tank to wash temperatures, which can vary with the type of wool being washed. The Vitodens controls are specially configured to allow it to provide the necessary elevated wash temperatures, something it does without difficulty.
The boiler also provides heat for two hot water baseboard zones for the barn. Unless it's very cold, the jacket losses from the solar storage tank, washing tank and drain back tank, as well as the wool-processing machinery in the barn, keep the space comfortably warm.
A tekmar 155 differential temperature controller regulates the solar system. When the collectors are hotter than the storage tank, the collector loop is filled with water from the drainback tank by two Grundfos 26-96 high head circulators. The pumps are plumbed in series to provide the lift to initially fill the solar loop. The tekmar 155 controller has a feature that turns one pump off after a time delay. Only one pump is needed to circulate the collector loop after the siphon is established in the solar collector loop.
The tekmar 155 differential control also tracks the circulator run time as well as supply and return water temperatures. The controller calculates and logs an accumulated value - “delta-T hours.” Multiplying this value by the operating mass flow rate, in pounds of water per hour, yields the number of Btus that have been collected by the system. The flow rate is provided by the flow meter on the solar collector loop.
Big SavingsAt the time of my visit, Radiant Engineering's Courtney Carrier, responsible for much of the design and installation of the system, was able to calculate the energy that the system had produced in the one and a half years since it had been installed. The controller had accumulated 46,779 delta-T hours since startup. At the 15 gpm solar flow rate, the solar array was able to move over 350 million Btus (350,842,500) into the solar storage tank.
At last winter's price for propane in this area ($1.59 per gallon), the system was able to produce as much as $6,771 in savings. This figure was calculated using a high efficiency for the backup boiler of 90 percent fuel utilization. At these rates of production, Radiant Engineering expects the system may pay for itself in as little as six years while producing an annual return on the original investment over 18 percent, a rate or return that will grow as the price of propane increases! After payback, of course, this will be money in the owner's pockets.
Taking the earth-friendly concept a step further, the drain water from the wool-washing tank, with its load of minerals and organic matter, is collected in an underground tank. From there, after cooling, the drain water is pumped into a portable tank on a trailer mount. A tractor pulls the tank into the field for irrigation, and the organic matter and minerals are returned to the land.
What was particularly refreshing was how well the owners and Radiant Engineering worked together to arrive at the final product. The whole undertaking was a design-specific project. By working together, the owners were able to communicate in a way that allowed the Radiant Engineering team to design and build a system that exactly matched their needs.
About Thirteen Mile Lamb & Wool Co.Becky and Dave offer a selection of sweaters, blankets, hats and other wool products at their factory-direct store. However, you can see and order their products directly from www.lambandwool.com. In addition to wool from sheep, llama and alpaca, even bison fibers can be blended for unique yarns of a variety of texture and colors. Wool products produced by local fiber artists include incredibly soft sweaters, scarves, mittens and hats.
You can also order lamb and beef for the dinner table. The certified grass-fed, organic lamb and beef shows up on tables in exclusive restaurants as far away as Washington, D.C. Some politicians are eating well these days!