Eucalyptus is a genus encompassing about 700 species of shrubs and trees. Depending on the species and your point of view, eucalypti are either invasive species that threaten our water supply or incredibly productive species that are being used to disrupt traditional pulp markets.
As an example of the latter point, the largest pulp mill in the world today is located in Brazil and uses 100% eucalyptus. Designed to have an annual capacity of 1.5 million tonnes, Eldorado Brasil started up in 2012 and set a production record in 2018 of 1.89 million tonnes of eucalyptus pulp on a single production line.
Most eucalyptus trees are native to Australia, and some species exude a gummy substance when the bark is damaged, giving them the nickname “gum trees.” They are fast-growing hardwoods that grow well in tropical and temperate zones, but are generally not frost-tolerant. One feature that makes them grow fast is their huge capacity to extract water from the ground – up to 200 litres per tree per day. This can be beneficial; for example, as a means of reducing malaria through swamp drainage in places such as Algeria, Lebanon and Sicily. It can also be detrimental; a study following a record drought in Cape Town, South Africa that resulted in water rationing in 2018 recommended removal of invasive species including eucalyptus that are estimated to reduce the city’s water supply by 55 billion litres per year, or two months’ supply.
Eucalyptus for pulp and paper
Eucalyptus trees were first introduced from Australia to the rest of the world after the expedition to Australia of Captain James Cook in 1770. In the early 1900s, thousands of acres of eucalyptus were planted in California with the encouragement of the state government, to provide wood for furniture, construction and railway ties. The wood, however, proved to be unsuitable for railway ties, because the ties twisted during drying, and the wood was so hard it was very difficult to hammer in the rail spikes.
The development of eucalyptus fibres for pulp and paper began in the early 20th century, when scientists began experimenting with growing eucalyptus for pulpwood. The use of seed selection and cross-breeding techniques resulted in improved properties, such as disease resistance and the ability to drop branches, resulting in a very straight trunk with few knots. Clonal propagation resulted in faster results than planting from seed. The biggest breakthrough, however, led by Brazilian scientists, was in productivity, as a result of both genetic selection and plantation management strategies. The productivity between 1970 and 2015 increased from 10 to 50 m3/hectare/year, producing trees up to 18 m in height after only 6 to 7 years of growth. Eucalyptus plantations are now common in many countries. Earlier this year during a walking tour on Portugal’s coast, I walked through several kilometers of eucalyptus plantations and saw huge greenhouses where eucalyptus shoots were being grown for future planting. The major client for this wood is The Navigator Company in Setúbal, just south of Lisbon, which makes both pulp and paper at the site.
Eucalyptus fibres are short, slender and thick-walled compared to softwood fibres, but their length is very uniform, and they have low coarseness, which helps tissue softness. The short and slender fibres also result in good formation and high opacity when used for fine paper.
Implications for NBSK producers
The pulp furnish of the world has changed significantly as a result of the introduction of eucalyptus from Australia to the rest of the world 250 years ago and the development of fast-growing eucalyptus plantations over the last 50 years. One third of all global market pulp is now based on eucalyptus! In addition, recent research on the refining of eucalyptus pulp has allowed stronger sheets and better tissue quality. Fine paper can be made with 100% eucalyptus, something that was unheard of fifty years ago, when northern bleached softwood kraft (NBSK) pulp was a necessary additive for almost any sheet of paper. As southern producers such as Eldorado Brasil increase their production of pulp, NBSK producers will need to focus on specialty applications that benefit from the superior fibre length and strength of their fibres in order to maintain or increase their market share.
Martin Fairbank has worked in the forest products industry for 31 years,
including many years for a pulp and paper producer and two years with
Natural Resources Canada. With a Ph.D. in chemistry and experience in
process improvement, product development, energy management and lean
manufacturing, Martin currently works as an independent consultant,
based in Montreal. He is also an author, having recently published
Resolute Roots, a history of Resolute Forest Products and its
predecessors over the last 200 years.
Martin Fairbank Consulting
- Pulp and Paper Technology
- Materials Recycling
- Biorefinery Development
- Government Subsidy Programs
- Technical Writing
. White Papers
. Grant Applications
. Explain technical concepts
- Scientific Editing
. Review of articles for publication
- Project Assessment
. Evaluation of Technologies
. Project evaluation for funding agencies
- Pulp & Paper
. Conventional and emerging technologies