Technology Roadmap: Lumber and Value-Added Wood Products
4.21 Environmental Issues

Existing Technology

Bark disposal remains a major environmental problem for mills that are not equipped with cogeneration plants to burn it as hog fuel, many of which still rely on landfills. The disposal of sawmill residue has been a problem since the advent of the sawmilling industry. On the coast of British Columbia, the problem was virtually solved in the 1950s when coastal pulp mills installed boilers designed to use hog fuel. Today, there is a relative balance between the coastal pulp industry's consumption and the coastal sawmilling industry's production of hogfuel. The result is that, while there are periodic imbalances, particularly with respect to cedar hog fuel, there are no beehive burners in coastal sawmills.

Elsewhere, restrictions on beehive burners and open-air combustion in general have created a very awkward situation. In the absence of alternative disposal methods, mills have installed some form of multiple-chambered incineration with emissions scrubbers installed. This involves capital expenditures of $4 to $6 million per sawmill to reach the regulated stacked emission particulate standards. Many mills do not have access to this capital and may be faced with shutting down. Other mills have installed boilers to produce heat for their kilns, but these only use part of their by-products. Clearly there is a need for the development of cost-effective alternatives to current incineration methods, and rising oil prices may provide the right climate for some action.

A number of proposals in the area of co-generation, or wood-fired electrical power production have been brought forward in attempts to deal with the problem. Typically, a sawmill operation can only utilise about one-third of the electrical energy it would produce from its own wood waste. If the mill cannot sell the surplus energy at a reasonable price, the project becomes economically unfeasible. The company attempting to utilise power production to solve the burner problem must deal with a number of factors over which it has little or no control, such as government policies regarding energy pricing, power export restrictions, natural gas prices, and changing demand for electrical energy.

With regard to drying, the industry has had to deal with dehumidification or vacuum drying systems discharging a condensate which generally carries traces of many chemicals naturally occurring in the wood. These are generally the volatile portion of the wood extractives which become a gas in the kiln atmosphere and then condense out with the humidity in the air. Some producers have to buffer the pH of the condensate before discharging it into a sewer or septic system.

Volatile organic compounds (VOCs) emitted by all heat-and-vent and some dehumidification kilns are not regulated at this point. Given that venting occurs through a number of vents, not to mention leaks around doors, any strict regulation of gaseous emissions from kilns would require major physical changes to current kiln design.

Disposal of waste hydraulic oil, which is contracted out to specialised companies, remains an environmental issue for the industry. Hydraulic systems are present in every sawmill. Alternating current drives have replaced hydraulic equipment in some applications, but they are unlikely to become an acceptable substitute in all situations.

Other environmental issues in sawmills include control of dust, noise and vibrations. For many years, equipment manufacturers have been improving machine design to deal with these problems through better enclosures and other devices. Helical planer knives have been used to reduce noise levels. Generally speaking, it has been observed that sharp and well balanced tools operate more quietly (this is particularly true of sawblades); in other words, well maintained tools serve both productivity and environmental objectives.

Countries such as Germany have imposed restrictions on lumber wrappers used to protect dry lumber from moisture; they must be recycled. As measures of this kind become more common, there will be increasing pressure to use only wraps that can be recycled.

Incremental Technological Innovation

• Continue developing lumber manufacturing equipment with improved features regarding noise and vibrations.
• Develop fuel-cells or smaller co-generation units that would allow more mills to produce electricity and sell surplus power back to the grid.
• Pursue research on VOC emissions from kilns and methods to minimise such emissions.
• Develop cost-effective environmentally-friendly hydraulic oils.
• Devise recycling methods for lumber wrappers or effective ways to protect dry lumber without the use of wrappers.
• Pursue research on antistain treatments with low environmental impact.
• Pursue research to help the wood composites industry utilise a larger portion of sawmilling byproducts.
• Pursue research to help industry recover increasing amounts of solid wood (shorts, trim, etc.) through remanufacturing and value-added operations.
• Pursue development of methods to collect and treat leachates from log yards and other critical areas.

Breakthrough Technological Innovation

• Develop a comprehensive strategy to identify commercial applications for bark or its derivatives, and propose a research and development program to create the necessary technology within parameters of economic feasibility.