How to build a chip burner
When John and Anita Deming decided to clear some "field pine" from his newly acquired property, they wanted to do it efficiently and in an economically feasible way.
The so-called "field or pasture pine" was primarily a stand of white Scotch and red pine that had taken over an old pasture and was of little commercial value. Due to the stand's density, the trees would most likely become stagnated, thus limiting growth.
"Due to the quality of trees in the old field, chipping is the only financially viable solution," John said. "Traditional logging and pulping is too labor intensive."
Since the trees' small diameter and knotty nature prevented them from being used for lumber, the alternatives were either pulp, or to be chipped.
The pulp market has decreased as witnessed by the International Paper mill in Ticonderoga cutting back its production.
Deming contracted with Jim Pulsifer of Lewis to put his Mobark Chipavestor to work.
The Chipavestor devours the trees and branches at a rate of 90 tons per hour. Thus, a semi trailer, which can hold approximately 30 tons, can be filled in about 20 minutes. It's not like a backyard chipper or even one used by the highway departments or power companies when they chop up downed trees.
The $350,000 behemoth Chipavestor features 22-inch-long knives that rotate at 2,200 rpm and can chip trees with diameters of up to 27 inches.
Pulsifer of Lewis joined his father, Phil, in the logging business in 1971.
"This was to be just part time until I decided what I wanted to do," quipped Jim.
He likes what he does and has a loyal crew; several employees have been with him for 20 or more years.
"It's hard to get new help," Jim said.
The youngest in his employ is 38 years old.
The market for chips fluctuates, but right now they're going for $25 per ton. This is approximately the same as pulpwood.
"Everything is dropping," Pulsifer said. "That's why we have multiple markets. If you put all of your eggs in one basket, you're asking for trouble."
Using conventional logging on a site like this poses problems with the branches and tree tops. If the tree remainders are left, especially conifers, they become a fire hazard, and controlled burns promote pollution. So, after a regular logging job, Jim and his chipper are often employed to clean up as site.
Pulsifer contracted with the Joseph C. McNeil Generating Station, which has been producing electrical energy for Burlington, Vt., Central Vermont Public Service, Vermont Public Power and Green Mountain Power since early 1984.
The chips are trucked to the Swanton site and then transported by rail to the plant in Burlington. The plant consumes up to 76 tons of chips per hour, which equates to approximately 180,000 tons annually. This is equivalent to 360,000 barrels of oil per year. At full capacity, the plant generates 50 megawatts of electricity.
Air-quality-control devices reduce the emissions to one-tenth the level allowed in Vermont. Another advantage to facilities such as McNeil is the capacity to burn green wood, and thus there is no curing time needed.
New boiler types
Advanced Climate Technologies (ACT) is one manufacturer of wood-pellet and wood-chip boilers, which are used for commercial and multi-family residences. Their boilers use a two-stage gasification process that promotes complete burning.
During the burning process, the fuel is heated to 750 degrees, which releases the volatile gasses. Then air is injected to raise the temperature up to 2,000 degrees, and the volatile gasses are burned. Exhaust gasses are then sent through a heat exchanger to transfer the heat to the boiling water.
Currently, chip burning is not recommended on a small scale, such as a family dwelling. This is primarily due to the difficulties of accurately and safely feeding the stoves and furnaces. In addition, smaller units with today's technology would have considerably higher emissions of carbon dioxide and other gasses as well as particulate matter. Regular wood stoves and pellet stoves are not designed for the burning of wood chips.
E-mail Alvin Reiner at: firstname.lastname@example.org