Unlocking the chemical ‘treasure trove’ hidden in our forests

Monday, 11 August, 2014
Forest-based industries have long been a significant part of the European economy, converting wood into pulp, paper, cardboard, energy and a range of other wood-derived products. However, the side-streams of these industries contain a potential treasure-trove of valuable materials which have not been fully exploited so far. These materials include precious compounds known to have anti-cancer properties, which have in effect been discarded as waste.

The mission of the AFORE research team was to find a way to unlock this treasure-trove. The researchers worked on developing techniques to separate out the valuable chemical constituents in a manner that was both technically efficient and economically viable. Success would mean opening up a vast new source of materials that could be used in industries ranging from pharmaceuticals to cosmetics, food, fuels, carbon fibres, composite materials and bulk chemicals.

The potential value that could be released is enormous. In the predominant wood-pulping process used today (known as ‘kraft’ pulping), less than 50% of the wood biomass which is fed in at the start actually goes into the pulp used to make paper and cardboard. Almost all of the remainder is diverted into low-value ‘sidestreams’. These include being incinerated to produce energy, being used for landscaping purposes, or just left on the forest floor as a form of compost.  

Two main factors have stood in the way of the better utilisation of these side-streams. One is the lack of adequate techniques to separate out and upgrade the target compounds. The other has been the relatively low cost of alternative products derived from the oil industry. The need to move away from fossil fuels and the rising oil price decisively removed the second of these obstacles. The stage was therefore set for the development of new chemicals, polymers, materials and fuels from forestry side-streams – if only the right techniques could be found.

“The challenge, with the compounds we were seeking to isolate, is that to get them to the purity that is required, extensive and sometimes difficult sets of separation steps are needed,” explains AFORE’s Project Coordinator, Dr Anna Suurnäkki of VTT Technical Research Centre in Finland. “One of our main challenges, therefore, was to get the separation technology to a high degree of efficiency and specificity, otherwise it would not be commercially viable,” she adds.

Even when the technology had been developed, the ‘key’ to the waiting treasure-trove was still not guaranteed. “It takes a lot to upscale from the laboratory to a full pilot process,” says Dr Suurnäkki. “It is not just a question of using bigger machinery.”

Ultimately, AFORE team identified six technologies which were successfully demonstrated on a pilot scale. These included two methods to separate out a compound known as xylan. One of the types of substances known as hemicelluloses, which form the cell walls in plants, xylan has a number of applications. Among other things, it can be used as an additive to concrete to make it flexible, it can be used to manufacture glues, and to prepare health supplements in foods.

Another successfully demonstrated technology was a method to extract certain acidic compounds from birch bark which have been shown to be effective anti-tumour agents. The project team also developed a technology for fast, high temperature processing (known as catalytic pyrolysis) to treat lignin, another key component in wood biomass, which results in the production of bio-oil, which can be used as a fuel.     

At a time of increased global competition and heightened environmental awareness, the breakthroughs achieved by AFORE researchers have opened up the possibility of a multiple ‘win’ for the forest-based sector, demonstrating how the industry can not only deliver greatly increased added-value, but it can also reduce waste and improve sustainability.

“It is now a matter of each company in the forest-based sector needing to look at its own business opportunities and decide which approach to take,” concludes Dr Suurnäkki. “There will be new opportunities for SMEs as well, through new partnerships within various product value chains. We did market assessments, and what we know is that the attitude to new wood-derived products is very positive.”  

Forest biorefineries: Added-value from chemicals and polymers by new integrated separation, fractionation and upgrading technologies
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