Wood Residue-to-Fuel

The lumber industry has transformed the material that used to be swept off the woodshop floors and discarded, from a byproduct to a coproduct. Biomass Magazine takes a look at how Tolko Industries Ltd. and Nexterra Energy Corp. are turning wood residue from a plywood mill into a fuel to help power the milling process.
By Michael Shirek
It wasn't long ago that the owners of the plywood mill in Heffley Creek, British Columbia, were feeling the pinch of rising energy prices. Using natural gas to heat water for log conditioning and dry-veneer processes was becoming more costly each year as the price of the fuel climbed. As it turned out, the solution to the mounting energy bills came from within the mill itself.

Tolko Industries Ltd. makes structural-grade plywood at its mill in British Columbia. In the process of making three-eighths inch and 1 inch plywood, the mill produces tons of green bark wood residues. Instead of piling that unused biomass onto a compost heap, Tolko enlisted the help of Nexterra Energy Corp. to turn the residue into the energy needed to power portions of the mill. Nexterra's inside-the-fence wood gasification process began operating in May 2006, and has helped Tolko counter rising energy costs and to reduce the amount of carbon dioxide that is released from the plant.

"This project represents a strategic investment in a new technology that will help us become more competitive and energy efficient," Jim Baskerville, Tolko's regional manager of veneer and plywood, said at the outset of the project. Two years later, that strategic investment continues to pay dividends. Instead of paying steep natural gas bills, Tolko is replacing 235,000 gigajoules (65.3 million kilowatt-hours) of energy per year with heat provided by 25,000 metric tons (27,600 tons) of wood residue. The wood gasification project has replaced 40 percent of the mill's natural gas consumption, an amount equivalent to the volume of natural gas used to heat approximately 1,900 homes in Canada's western-most province. By using synthetic natural gas (commonly referred to as syngas) produced in-house, the mill saves an estimated CAN$1.5 million in annual energy costs.

Nexterra's wood gasification unit converts wood residue into syngas via a starved air process where only 20 percent to 30 percent of the oxygen required to fully combust the fuel is allowed into the process. Only a small portion of the wood fuel is fully combusted while the rest is converted to synthetic natural gas. The lone byproduct of the process is a granular ash that Nexterra says contains virtually no unburned carbon.

Nexterra President and CEO Jonathan Rhone says the project is working so well that his company and Tolko are teaming up on a similar project at another of Tolko's mills. With the continued high price of natural gas, Tolko isn't the only company interested in the gasification process. Rhone says his company continues to draw interest in the industry. "When we first established Nexterra in 2003, many of the companies we approached were skeptical that higher natural gas prices were here to stay and climate change was really on the edge of the radar screen," he says. "Many believed that price increases and related volatility were the result of normal temporary commodity fluctuations. Today, virtually all companies we deal with in the forest products and other energy-intensive industries are making energy a strategic priority and the leaders are investing in becoming energy efficient. Inside-the-fence [fuel] generation is increasingly viewed as essential to reduce and control energy costs."

Ancillary Benefits
While the improved bottom line for Tolko has been a positive result of the wood gasification project, the environmental impact is drawing attention outside of the accounting department. By replacing natural gas with an inside-the-fence fuel produced from biomass, Tolko and Nexterra say that the Heffley Creek mill cuts greenhouse gas emissions by 12,000 metric tons (13,200 tons) a year. The companies say this is equivalent to taking nearly 3,000 cars off the road. Tolko estimates that over the expected life of the energy system, the company will have reduced carbon dioxide emissions by 300,000 metric tons (330,000 tons).

Although it's possible to simply burn the wood residue to produce heat for the mill's operations, wood gasification has its advantages. Converting solid waste into gas allows the energy to be used as a replacement for, or a supplement to, current natural gas-powered operations. The emissions from combusted syngas are also less environmentally invasive than those from combusted wood.

Nexterra's gasification unit is designed to create syngas from a variety of wood fuels, including material with as much as 60 percent moisture content.

Other Applications
Rhone says the benefits of inside-the-fence energy generation aren't limited to the forest products industry. The industry continues to find innovative ways to use previously discarded biomass to generate energy and displace fossil fuel consumption. "The interest we are seeing is not just in the forest industry," Rhone says. "We are also seeing tremendous interest in our gasification technology in other sectors. For example, institutions such as universities, government facilities, military complexes and hospitals all consume large volumes of natural gas and fuel oil for heating and hot water. We are active in that market."

Interest in Nexterra's biomass gasification process also isn't limited to Canada. The company is currently involved in a project with Johnson Controls Inc. to provide energy services in the United States. The pair's first joint project is a biomass gasification system at the University of South Carolina in Columbia. The project will use wood residue from area sawmills to produce heat, hot water and electricity for the campus.

Nexterra also sees a future market for biomass energy that's generated outside-the-fence. "Another sector we're starting to work with is the power generation industry where utilities across North America are buying green power from biomass and other forms of renewable energy," he says. "We are in the process of completing a strategic alliance with a major independent power producer with the objective of implementing more than 100 megawatts of small-scale biomass gasification power plants over the next several years. This is just the beginning. We see tremendous growth potential in the power generation sector for our products and technologies."

With no shortage of biomass and no relief in sight from elevated energy costs, Nexterra is now banking on a market that extends beyond the fence.

Michael Shirek is a Biomass Magazine staff writer. Reach him at [email protected] or (701) 746-8385.