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WisconSUN Case Study:
Timbergreen Forestry - Solar Wood Drying Kiln
Owner: Timbergreen Forestry
Location: Spring Green, WI
Cost: $5,000 (materials only)
Size: 600 ft2 of collector area1
Description: Active solar thermal
Installed: 1998
Timbergreen
Forestry2 is a for-profit
family-owned business. Every attempt is made to limit the environmental
impacts of Timbergreen's lumber production. Timbergreen strives to become
a model for value-added cooperatives that produce high quality hardwoods.
The "solar-cycle" kilns at Timbergreen use a simple design. Each kiln has four rooms and holds 14,000 board feet. Three open rooms store wood stacks while they air dry. Once the wood stack is sufficiently dry the room is closed using a sliding front door and all heat from the rooftop active solar system is directed into the kiln room. Under optimal conditions, drying takes four months
On a sunny day the temperature inside the kiln room is about 50oF greater than the outside temperature. Electric fans circulate the hot air in the kiln room. The energy costs for drying is about $0.01/board foot of lumber.
The
wood drying kilns are simple and easy to use, and are best operated on
a small scale. Because of the slow drying and daily temperature cycling
they also deliver a very high quality product. The life-cycle cost of
the solar kiln compares favorably with other wood drying options including
wood fired kilns and dehumidification kilns.
1 A solar kiln with a 2000 ft2 solar collector was recently installed at Sustainable Woods Cooperative, Lone Rock WI.
2 Visit Timbergreen Forestry at www.timbergreenforestry.com or call Jim Birkemeier at 608.588.7342. Blueprints for the solar kiln are available.
Photo Credits
Jim Birkemeier, Timbergreen Forestry
copyright © 2000 WisconSUN
