Harnessing the Sun

FOR RELEASE TUESDAY, AUGUST 14, 2001

CONTACT: Jack De Vore Jr., associate professor of vocational education

(501) 575-7285, [email protected]

Jim Snow, instructor in vocational education

(501) 575-7354, [email protected]

Macadda J. Peoples, science and research communications intern

(501) 575-7034, [email protected]

HARNESSING THE SUNUA Researchers Discover Free Energy Can Yield Valuable Industrial Products

FAYETTEVILLE, Ark. -- From rolling blackouts resulting from energy scares in the West to high gas prices across the U.S., news about the nation's energy crisis has perplexed, captivated and panicked Americans. However, University of Arkansas researchers Jack De Vore, associate professor of vocational education, and Jim Snow, instructor in vocational education, do not worry about energy crises. The two faculty members in the College of Education and Health Professions have demonstrated that energy is neither scarce nor expensive. All they had to do was look to the sky.

A sturdy, hand-crafted, wooden desk graces a corner in Jack De Vore's office. Though handsome in design, the desk itself is not a conversation piece. The red and white oak De Vore used to construct it, however, is quite remarkable. It represents nearly 15 years of tinkering and perfecting an apparatus designed to dry wood using solar energy.

"The timeliness of this is perfect, and the U of A has it," De Vore said.

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, when the inventors used a $1,500 grant to produce a solar kiln to dry wood for students taking industrial arts classes. The project was a valuable learning experience for students and produced a usable commodity for class work. However, as with other solar kilns, the drying process took three to four months.

So De Vore and Snow began to tinker with the kiln's design. The tinkering became a 14-year obsession. They poured another $400 in the project to create a computerized model that tracked inside and outside temperature, inside and outside humidity and air movement. The monitoring system and the assistance of a cigar-smoking janitor 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 from a hobbyist's project to a valuable commodity for the timber industry.

"Jim and I realized 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, at a final cost of $2,100, 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 which 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.

"When we put in 1,000 board feet of wood, we get out 1,000 board feet of wood," De Vore said.

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

"You can make it on a trailer frame and do all your drying in the woods," Snow said.Also any wood waste that is created can be safely returned to the forest floor.

Perhaps the greatest commercial appeal of the kiln is that the lone cost is building materials."There's not a lot of money in any of this," Snow said.

Figures from a sawmill in Arkansas estimate that a board foot of oak costs $1.25 before it is kilned. The energy costs to operators of commercial systems after wood has been kilned raises the cost to between $3.50 and $4.00 a board foot of oak. De Vore and Snow also pay $1.25 a board foot for pre-kilned oak. The difference is that after they dry the lumber in the solar kiln the cost per board foot of oak is still $1.25.

"There is no energy cost," De Vore said. "It is totally passive."This creates a potential savings of $2,250 to $2,750 for every 1,000 board feet of oak. Imagine the savings for commercial producers who kiln hundreds of thousands of board feet per year.

De Vore and Snow have published 29 articles concerning the solar kiln in trade journals. In 1998, they received the approved rights for two foreign licenses. On June 29, 1999, De Vore and Snow were granted patent number 5,915,811 for the solar kiln. They have been granted two more patents for curvilinear solar panels and curvilinear interiors. The three patents have a combined 22 claims.

"These are the first and only patents that the College of Education has ever received," De Vore said.

The lumber industry is not the only sector that can benefit from De Vore's and Snow's technology. The potential uses for the kiln and its parts are innumerable. Uses for the technology range from heating pickle brine and catfish ponds to drying lucky rabbits' feet and plants for the florist industry. Perhaps the greatest potential use of the technology is for house heat. De Vore and Snow are confident that with minor modifications the technology can be a viable alternative to gas and electric heating systems.

Jack De Vore has taught industrial and technological education for over 30 years at the University of Arkansas. Jim Snow, who has been a UA faculty member since 1979, also teaches industrial and technical courses for the department of vocational and adult education.