Solar kiln is kind on costs

University of Arkansas researchers Jack De Vore and Jim Snow have created an environmentally friendly solar powered kiln that could save the timber trade thousands of dollars a year.

For wood to be valuable and usable by contractors for interior building materials, it must have less than 9 percent moisture content.

The predominant method of wood drying uses kilns fired by gas, oil or wood waste, a procedure that takes at least two to three weeks and requires significant consumption of energy.

With this traditional method, nearly 20 percent of the wood product is lost to waste because of warping, cracking, discoloration and case hardening.

De Vore and Snow developed a solar kiln that dries wood as efficiently as the current method and retains 100 percent of the wood product.

The De Vore - Snow solar kiln traces it's beginnings back to 1987, although the original model took three to four months to dry wood.

So De Vore and Snow began to modify the kiln's design over a period if 14 years. During this period they created a computerised model which tracked inside and outside temperature, inside and outside humidity and air movement.

The monitoring system led De Vore and Snow to curve the interior of the kiln. Although these enhancements improved performance, a simple modification to the solar panels turned the kiln into a valuable commodity for the timber industry.

'Jim and I realised we weren't getting enough heat, so we bent the solar collectors,' De Vore said. 'All solar collectors are flat. We have the patent for curvilinear collectors.'

Using an unorthodox and unproven theory, De Vore and Snow increased the surface area of the corrugated tin solar collectors by bending them. Because of this, each of the six collectors always has direct sunlight.

'Each collector has the same surface distance, we added an additional 4 feet of collectors by bowing them,' Snow said.

In 1995 De Vore and Snow produced a kiln that dried green oak lumber to within 6 percent to 9 percent moisture content within 14 to 21 days.

The design is simple, resembling a 9.5 feet by 14 feet backyard storage unit.

The only moving parts in the design are the six fans that help to foster air movement. Even they are solar powered by a photovoltaic cell. Thus, the final product became the only totally passive, commercially viable solar kiln in existence.

De Vore's and Snow's kiln not only lacks energy costs, but also returns 100 percent of the wood product.

Rather than applying constant heat to the wood, the solar kiln cools at night, allowing the moisture in the wood to rise to the surface. The process gradually pulls all of the moisture from the wood's surface, rather than evaporating the moisture from the interior, which causes wood damage.

Additionally, it is an environmentally sound alternative to traditional methods, causing minimal pollution and waste. Because the solar kiln is constructed of lightweight metal, it can be moved to the forest, providing a single location for the entire commercial lumber process.