Using solar power to add more precision to the tobacco curing process has proven to be a time and money saver in tests at Virginia Tech University and at Clemson University’s PeeDee Agriculture Research and Extension Center in Florence, SC.
Modern tobacco production is often time and labor intensive. Tobacco curing can make or break both quality and profit in a tobacco crop.
Curing takes about 20 percent of variable cost and 15 percent of the total cost of tobacco production.
A new hybrid energy source tobacco barn that uses solar power and propane, under development by North Carolina-based Long Tobacco Barn Company (LTBC), was one of the highlights of a recent Farmer Field Day at the Pee Dee Station.
Speaking at the field day, Clemson Researcher Russell Henderson said, “Tobacco barns currently in use have an insulated curing chamber. The solar powered barn has no side-wall or roof insulation; instead it has an air pocket that collects solar heat. When you walk into the prototype solar barn here in the middle of the day, the temperature is much higher than in a conventional tobacco barn.”
In the solar barn, air comes into the curing chamber from the bottom of the side walls via an opening that runs the length of each side of the barn.
Air is pulled through the air pocket around the curing chamber and back to the burner. This allows for capture of the solar heated air that is generated in the air pocket, as well as any heat that escapes from the curing chamber.
A new standard tobacco barn costs about $36,000, while $35,000 is the projected price of a comparable sized solar barn. Hopefully, there will be a Federal tax credit of about $7,000, so the net cost of the solar barn should be a bit lower than a standard barn once they get to the market.
Bob Pope, owner and general manager of LTBC in Edgecombe County, N.C., was on hand at the field day to provide more technical details of the solar powered tobacco barns.
"The solar collector that surrounds the curing chamber works passively by conducting heat directly into the curing chamber through the black corrugated steel collector plate that forms its walls and ceiling. It also works actively by pre-heating fresh air used for curing before it enters the barn's propane-fired furnace," Pope said.
LTBC's barn not only uses the cost-free power of the sun, it has been shown to shorten the time the tobacco needs to be dried. The barn accomplishes this by wrapping the curing chamber in a solar air collector. On sunny days, the barn's solar collector maintains a constant temperature of up to 135 degrees Fahrenheit.
David Reed, an Extension agronomist at Virginia Tech, has conducted studies on the solar barn's curing efficiency, specifically testing the pounds of tobacco cured per gallon of fuel used in the curing process for the past three years.
29 percent curing efficiency increase
While the Virginia researchers have averaged about 25 percent less fuel usage, he says, "Data from 2009 indicate an average gain in curing efficiency of 29 percent over seven cures.”
Cliff Keel, who grows tobacco near Robersonville, N.C.,, says about the solar barns, "I had my second thoughts, but we ended up using it," says Keel. “This barn cures bright clean tobacco a day and a half earlier than standard barns,” he adds.
Wallace Roberts, who farms near Lawrenceville, Va., says, “We’reseeing up to 35 percent savings on fuel. We can cook out 12 to 24 hours quicker with our solar barn, and we can put more tobacco in the boxes.”
After the tobacco buyout in 2004, tobacco production in the Upper Southeast dropped dramatically and many farmers, especially those who farmed smaller acreages, quit growing the crop.
However, demand from Europe and Asia for high quality U.S.-grown tobacco has brought tobacco acreage back over the past few years — not back to pre-buyout days, but production has increased steadily in recent years.
Experts contend as much as 70 percent of the tobacco grown in the Carolinas and Virginia this year will be exported.
Tighter human safety regulations by overseas buyers also point to a need for more precise tobacco production, from start to end in the production process.
Tobacco curing has long been much more of an art than a science, but new regulations point toward a more precise industry and economics point to a more cost conscious industry, both of which fit well with the future of solar-powered tobacco barns.
The ‘new’ tobacco industry is a bit different and entrepreneurs like Pope, who has been in the tobacco business in one way or another all his life, contends technology will play a bigger part in tobacco production, primarily because most of the production now is being done by much larger farming operations.
The end of the Federal Tobacco Price Support Program in 2004 released growers from acreage restrictions and withdrew the financial backing that helped stabilize tobacco prices at artificially high values.
The original idea for a solar powered tobacco curing barn came as a result of the energy crisis back in the 1970s.
Pope was at the time an architecture student at North Carolina State University, where he drew some initial plans for a solar tobacco barn.
After graduation, Pope built six wood-frame demonstration rack and small box solar barns in 1978 and 1979 that proved the concept. However, the barn market was saturated by then and demand for Pope’s new style barn did not develop.
Pope says that, after three years of research with his solar powered barns at Virginia Tech and two years at the Pee Dee Research Center in South Carolina, some lessons have been learned that have resulted in revisions that will be incorporated in the production model of the solar barn now on the drawing board.
“One thing we’ve learned is that, when drawing fresh air through open vents at the bottom of the side walls that run the entire length of the barn, more air comes through the back of the collector than from the front.
“This results in inefficient use of the heated air in the collector. We will correct that deficiency in the production model of the barn.”
Pope says the solar tobacco barn may be ready for commercial application as soon as next year.