Get more out of the forest with better processes

​Man has always lived on and off the forest. Today Sweden is one of the world's most important producers of products from forest raw materials. The Wallenberg Wood Science Center now receives an additional SEK 380 million for wood research with the goal of creating new material and making the processes more sustainable and energy efficient.​
Hans Theliander“The grant is a fantastic thing. We have been working with the center for almost 15 years. This means that you get an additional number of years to work with these things and expand the portfolio”, says Hans Theliander, professor of Forest Products and Chemical Engineering at Chalmers, and one of the researchers at Chalmers who has been with the Wallenberg Wood Science Center since the start in 2009.

In his head he has a sequence for how the wood material of the forest can be used better. Think about reusing each carbon molecule 40 to 50 times before turning it into carbon dioxide. In the future, the forest industry will be far more than planks and paper.
“In a first step, different sawn products can be manufactured and used for different purposes for several years. It can be, for example, in buildings or furniture. Then you can use the wood material in these products to produce pulp fibers, for example you can use it to make paper packaging or writing materials - when you have circulated the fiber material a number of times and the quality of the fibers is no longer as good, you could pick out nanocomponents and make different materials of nanocellulose which in many cases can replace today's plastic materials, circulate these a number of times to then extract cellulose polymers and make various textile materials, for example viscose”.

“I'm not done with that, says Hans Theliander, after this you can pick out the sugar molecules that are in the textile cellulose-based materials, and ferment to ethanol, a raw material for several different chemicals, not least fuel. I can take several other examples. We must start thinking in that way to make the most of the forest in the future. But then it is important to adapt the processes and material types. Future researchers have something to do here”, says Hans Theliander.
Already today, the sawmills and pulp mills, has a good start to a sequential order In the sawmills, which are the important thing, it is sawn up to become planks. The residual streams from sawmills in form of sawmill chips together with thinning wood from manage of the forest, can go to the pulp mills. Add to this the extensive paper recycling, and we already have the first steps. But it is of course important to expand this. The Wallenberg Wood Science Center was started in 2009. The focus is on basic research that aims to develop knowledge as a basis for a new generation of innovative materials from trees.

Lisbeth Olsson“Sometime in 2008, the Wallenberg Foundation held a large workshop with researchers from several subject areas on forest renewal. After that, an announcement was made in the area addressed to the universities. The result was a center between KTH and Chalmers University of Technology. Later, Linköping University would join. It was a ten-year venture. This is how the Wallenberg Wood Science Center was started”, says Lisbeth Olsson, professor of Industrial Biotechnology, who together with Hans Theliander and Paul Gatenholm, professor of Biopolymer Technology, is the initiator of the center at Chalmers.

“The philosophy at Wallenberg Wood Science Center is to develop milder process methods so that you can retain more of the structure of lignin and hemicellulose, based on building new materials where the inherent properties of the wood are utilized. The goal is to make the entire manufacturing process more energy efficient. An example of this is drainage. When to get the fiber out - it is a solid material you should have in the end. That process is enormously energy-intensive, this is what Hans Theliander works with”, says Lisbeth Ohlsson.

Hans Theliander's track record as a researcher and innovator in the sulphate factory's recycling processes is long. In recent years, he has worked with filtration and extraction of lignin. The process - LignoBoost - is today commercialized and is in operation at two pulp mills in the world. It has the potential to be a central technology in the pulp mills of the future. Hans has also been active in pulp technology research with significant contributions concerning, among other things, heat, and mass transport during cooking and in biorefinery-related studies where mathematical modeling has been central.
Knowledge from different areas is needed to ultimately be able to produce exciting new materials from the forest raw material, here several different specializations in materials and process technology are important. When it comes to the more "chemical" aspects, the whole spectrum is needed from basic chemistry, via applied chemistry to chemical engineering.

“My research area is about the processes needed to produce different types of materials from wood raw material. It may not be quite as “sexy” as the material itself but is of course one of the prerequisites for being able to produce different products from wood material. 20 years ago, the balance was good between chemistry, applied chemistry and chemistry / process technology. At present, there is a great imbalance”, says Hans Theliander.
“Today, it is primarily material technology that has increased. While Chemical engineering has decreased, which is a problem”, says Hans Theliander, not only at Chalmers, but also internationally and this is a problem since engineers with that competence are needed.
“It has been a big loss in the field of chemical engineering or process engineering as it can also be called. 20 years ago, Chalmers really had competence and good momentum in that business. But since then, several professors have retired without new recruitment”, says Hans Theliander.

The challenge has also been observed in the industry, which has been involved in initiating a new bio innovation program called "Resource-smart industrial processes". The goal is to strengthen process / chemical engineering in Sweden. The program is the reason why Hans Theliander still works 40 percent.
“The idea is now that Merima Hasani, researcher and associate professor in the field of Forest Industrial Chemical Engineering will take over after me. It is a national program at Chalmers with eleven doctoral students and postdocs and funded by Vinnova, the industry and academy”.

What does the development of process technology mean for the forest industry?
“This is about a lot. Historically, the energy has been quite cheap, which has meant that when these processes was developed the smartest and most energy efficient process solutions was not used. Some improvements have been done during the years but with improved knowledge in chemical engineering and process engineering, it is possible to optimize the processes much further and make them more energy efficient and utilize the forest material better: in the end get a better material yield. If you look at a sulphate pulp factory today - you burn half - and half become pulp fibers. It is a poor material yield. You must increase it. Which has been one of my mantras for the last 15-20 years”, says Hans.
“People are starting to open their eyes to this, after all, wood is the most expensive part when producing pulp. You want as much out of it as possible”, he says.
Hans Theliander's research group has worked with several proposals on how, for example, you can also use branches and tops in a smarter way. Today, fine pulpwood is used as a starting material to make viscose.
“You can do it in another way. When you make viscose you need polymers, not a lot of fine fibers, it is enough that the polymer is okay - you can take it from branches and tops. These are the thoughts you must have in the future to make the biomaterial last”.

Hans ThelianderHow do you make the processes more sustainable and energy efficient?
“ I usually put it like this. We have a unique medium and that is water, which is also a good and environmentally friendly chemical. We should continue to use that. There are two problems with water, I usually jokingly say that one is 4.18 (kJ / kg K) - ie the heat capacity - that is, how much energy you need to use per degree and kilo of water.
The second is 2300 (kJ / kg) - it is so much energy you need to evaporate a kilo of water. It is a high heat of vaporization value. An example is: When we digest the wood, the pulp fibers are suspended in the cooking liquid. We wash the pulp fiber with water and the more water we use, the greater the energy demand are later in the process. Here it is important to make the washing of the pulp fiber more efficient, use as little water as possible, to minimize the heat demand in subsequent evaporation steps”.

Is water in short supply here?
“Well, it is probably not the lack of water, but it is costly energy wise to remove the water from wet products. This takes huge amounts of energy. Just to give proportion - a partial step in the pulping process is one evaporates and concentrates the black liquor. Every second in Sweden, more than one cubic meter of water is boiled away. Enormous amounts. It is done in a smart way today, but here there is so much more to do”.

Will the society demand less forest if one succeeds in making all these efficiencies?
“You can put it in that way, but you can also say that you need to get more out of the same amount of forest. We are about to replace petroleum-based products and given that we use enormous amounts of petroleum-based products – then our needs of other raw materials, and wood will be one of the most important, is enormous. To make the forest last than we really have to be efficient.
“What´s interesting is that not many people today know that 100 years ago it was realized that we needed to plant trees. Various laws were enacted on how forests where to be managed. That is why we have so much forest raw material today (about twice as much compared to hundred years ago). Had they not done so – Halland, south of Sweden, would probably have looked like certain parts of England. Green. With a lot of heathlands”, says Hans Theliander.

How the forest should be used best is discussed extensively by the various actors in society, what opportunities do you see in the future?
“Everything is interconnected and complex. There is a lot of politics in the whole thing. I really hope you get the right side of the discussion about the forest. In general, one can probably say that there are very well-managed forests in Sweden – and somehow, we should be able to use it in a sustainable way, but not over-utilize anything. With smarter process technology, we can help you get a higher efficiency of what you pick out of the forest. You then get more per ton of set-aside forest”.
“It is an important message about why you should refine process technology. Personally, I do not think it is effective when you burn the wood directly, but instead we will manufacture different materials and chemicals. That we then, after several re-cycles, use it as an energy source must be OK”.
“Another important thing – is that we should be able to reuse and circulate materials in a good way. Here, the forest industry has been at the forefront when it comes to collect different paper/board products and how to use the fibers several times. It is a good start, but we have to become even better and also expand it to other fields”, Hans Theliander concludes.

Text: Ann-Christine Nordin

Page manager Published: Mon 21 Feb 2022.