Story: Forestry research
Page 8 – Wood processing possibilities
Although radiata pine can be sawed, machined and treated more easily than other exotic woods, its properties vary from tree to tree, even when they are grown on the same site. Also, the wood within a single tree can vary markedly. Because of this, researchers have helped develop timber grading systems and building standards to ensure that the right wood is used for different purposes.
Because wood has a high moisture content, it must be dried in large kilns before use. Drying must be carefully controlled to prevent warping and bending of the timber. New Zealand research into the drying process leads the world. Breakthroughs include using high temperatures to dry wood as quickly as possible.
Preservative treatments to protect wood from insect attack and decay have been developed by chemical companies working with researchers. But, because public opinion has swung away from chemical preservatives, other treatments have been sought.
Using swamp kauri
In the 1920s researchers tested whether swamp kauri was suitable for pulping, as the sodden wood dredged up from wetlands was seen as useless for anything else. The fibres were found to be unsuitable for paper, but swamp kauri is now one of the most valuable furniture timbers in New Zealand.
One alternative is to use heat to change the physical properties of the wood and make it unpalatable to insects and fungi. Another process, known as acetylation, modifies softwoods at a molecular level so they behave more like hardwoods, with more stable and durable wood.
Pulp and paper
New Zealand research into pulp and paper production initially focused on native species, before moving to exotics. Because most pulp and paper technologies originated in the northern hemisphere, using spruce and other European species, New Zealand research into pulping and processing radiata pine was needed so the local paper industry could develop.
Methanol (also called wood alcohol) was the first fuel to be made from wood, but now researchers see ethanol as a more likely replacement for petroleum. It may also be possible to produce diesel fuel from wood.
Heat and power
New research aims to increase the production of renewable energy from wood. The forest industry often burns wood waste to produce heat for timber drying kilns. In large-scale commercial and industrial applications, such as sawmills, this energy can also be used to generate power.
Rising oil prices in 1973 prompted forestry scientists to develop a technology to produce ethanol from wood. While pilot studies showed promise, motivation flagged when oil prices fell.
Due to concerns about climate change and rising oil prices, interest in biofuels has recently resurfaced, as they are seen as a carbon-neutral alternative to fossil fuels. New research in this field is underway in institutions and companies throughout New Zealand.