This is the second in a series of three articles on the BioMax25 unit that Winn Ranger District recently began operating. See next Sunday's issue for the final article.
Scientists at the Forest Research Station here have been operating the BioMax 25, a biomass gasifier, for several weeks now, producing enough energy to power the ranger station, about 17 kilowats, and deposit an additional 5-6 kilowats onto Entergy's grid.
A gasifier is much like a home's back-up power supply unit, which normally runs on propane or natural gas. What's different about the gasifier is that it runs on gas produced from burning what amounts to wood waste.
"The BioMax 25 is an innovative, cutting-edge device, which will strengthen (the Winn ranger district’s) environmental, energy and transportation management," according to information provided by the U.S. Forest Service. "In a ground-breaking, first-of-its-kind partnership, the National Forest System, Forest Research and State and Private Forestry (the three branches of the U.S. Forest Service all of which are represented at the Winn station) have developed a program to provide cheap, clean electricity while reducing dangerous forest fuel woody biomass."
Soon, the scientists of Forest Research at the Winn station plan to begin producing synthetic diesel with the unit as well.
But more than anything, the unit will provide a platform from which the scientists can explore a number of issues, including what sorts of gases, at what levels, different types of wood can generate. The answer to this question, and others like it, can change much.
The leaders in the project, Forest Research Leader Les Groom, Forest Supervisor Gretta Boley and Field Representative Forrest Oliveria "will act as a catalyst in moving our country away from foreign oil dependency" according to the Forest Service.
The Forest Service staff operates the unit, making sure that each of two bins attached to the gasifier stay full of wood chips and that a barrel which collects the ash from the burned wood is emptied when it becomes full.
Other than that, they simply watch the unit go and record the information it provides them, Groom said. If something goes wrong with the unit, it automatically shuts down. Eventually researchers want to get a dedicated IP address to monitor the unit remotely.
Each bin holds about 700 pounds of dry wood, which produces about 14-16 hours of energy, or two days worth, Groom said. Two pounds of wood chips equals about 1 kilowatt. A small, level pick-up load of wood chips would run the gasifier for about eight hours.
While some moisture is needed in the wood to control the temperature and keep the reaction going as it should, much of the moisture is evaporated with waste heat from an exchanger.
The gasifier connects itself to Entergy's grid when sensors determine that the two can safely synchronize with one another, Groom said. When the grid varies, the unit disconnects itself again until synchronization can reoccur.
The wood from the bins drops down onto a vibrating shelf which "categorizes" the chips by size. Those that are too small or too large are separated and caught in a separate bin to be disposed of later. The correctly sized chips, about the size of a quarter, are sucked up a pipe and deposited into the gasifier where the temperature is about 800 degrees or higher.
The gasifier applies that heat under pressure in the presence of steam and a controlled amount of oxygen, which produces a gaseous mixture of hydrogen, carbon monoxide, carbon dioxide, and other compounds, referred to as synthesis gas or "syngas."
The gas is then taken through a process by which it is cooled and the ash from the wood is extracted. Then, the gas is injected into a generator which in turn supplies the electricity.
In all, the project cost the Winn Ranger District about $250,000, Groom said. Still left to purchase is the correct sort of wood chipper, another representative said, which might push the price closer to $300,000.
Similar units for homeowners are currently in the research stage, said Carl Peterson of Community Power Corporation, the company that sold the unit to the ranger district.
An average-sized home typically uses about 3-6 kilowats per hour, Peterson said. A 5 kilowatt unit would charge a battery pack which the house would draw upon.
Though not commercially available, there are three such units being researched at the Madison, Wis. Forest Service, Mississippi State University and Florida University.
A couple of other small companies in Scandinavia, Europe and Asia are also working on gasifiers, said Peterson. However, the units in India and Asia are not automated and require 10-15 people to operate.