If the world is to live within its environmental limits, the need to make the most sustainable use of its raw materials will become ever more vital. Increasingly, this will require us to focus on making maximum use of all the components of those raw materials, right down to the waste products. In today's world, everything has to be used.
High on the list of raw materials to which this applies is wood and its close relations. Such crops have the potential to generate a vast range of products in a highly efficient way – from paper to biofuel to chemicals. But only if we learn how to unlock their secrets and make optimal use of them.
Extending the boundaries of our ability to understand and derive maximum benefit from these materials was the central aim of LIGNODECO, a three-year research project backed by 3 million euros of funding under the European Union (EU)'s 7th Framework Programme.
The focus of the research was the use of two fast-growing, high-productivity crops found in abundance in Brazil – hybrid eucalyptus clones and elephant grass. The consortium brought together partners from both Europe and Brazil - four European research institutes, one Brazilian university and two commercial companies, Suzano Paper and Pulp of Brazil and Danish company Novozymes, a specialist in bio-innovation and industrial enzymes.
The top priority for the researchers of LIGNODECO (short for LIGNOcellulose DECOnstruction) was the development of new ways of treating the two crops using enzymes, chemicals or simple mechanical processes, or combinations of these, in order to deconstruct their cell walls and break the biomass down into its separate components.
The task was more than just to break it down, however. The challenge was to do it in an optimal way which would allow for the maximum exploitation of all the resulting components - including any waste materials, which had to be capable of being processed for energy recovery in the form of biogas, and with minimal water consumption.
The LIGNODECO group pursued two main routes. The first was the modification of pre-existing deconstruction technologies already in use in the paper-pulp industry. The second was the creation of new biotechnological methods based on the use of enzymes. Central to both was an in-depth analysis of the two crops to understand the nature of their key components (lignin, hemicellulose and cellulose) and how they behave under different circumstances.
The successful outcomes of the research included the production of a low-energy use, high strength paper pulp, with a 6% higher paper-production yield than other pulps. This was created by extracting complex sugars (xylans) from the biomass and then adding them to pulp produced from eucalyptus. This discovery, in turn, opened up the possibility of highly efficient, dual-production line plants. The first line produces pulps which require the removal of biomass xylans, while the second produces the high-grade, xylan-enriched pulp. This method has already been patented, and the establishment of a pilot plant able to produce one ton of pulp per day is now under discussion.
Among other promising results, a high-grade tissue pulp made from xylan-depleted elephant grass is also in the process of being patented.
The fundamental significance of LIGNODECO lies in its application of the newly emerging concept of the 'biorefinery' – a model whereby biomass is converted into a range of higher value-added products, with low wastage and minimal emissions. More specifically, at a time when sustainability and environmental protection are of paramount importance, LIGNODECO marks a major step towards the important goal of using wood derived products as substitutes for petroleum-based ones.
With its central focus on biofuel production, it also has the potential to contribute directly to the EU's policy target of deriving 20% of energy from renewable sources by 2020.