Today’s world is full of big challenges. Climate change, the depletion of fossil resources, ever increasing quantities of waste ending up in landfill or oceans, just to mention few. All these factors are driving us away from fossil-based fuels and materials towards bio-based alternatives. In Stora Enso, we believe that anything that is today made from fossil-based materials can be made from tree tomorrow.
Often the first step in a process of converting a tree into a new product is chemical fractionation of biomass. Today, the dominating way for doing this is the Kraft pulping. Developed to produce paper, Kraft process has been perfected over its one and half centuries as industrial process. And indeed, it offers an excellent process to produce high quality pulp from a variety of feedstocks, utilizes a closed-loop recovery of cooking chemicals and produces a surplus of energy.
Yet Kraft process is not an omnipotent answer in all cases. Modern Kraft mills require vast quantities of feedstock that needs to be harvested over large areas and distances to maintain profitability of the large investments needed. Consequently, regions for new mills are becoming hard to find. The issue is not made any easier by the fact that Kraft process struggles with many non-wood feedstocks.
Fractionating biomass with organic solvents offers a powerful alternative.
GVL, or gamma valerolactone, has established itself as a powerful solvent for biomass fractionation. There are several intrinsic benefits with GVL. To start with, GVL fractionation exhibits excellent mass yield because, unlike in the Kraft process, carbohydrates are not lost in alkaline-catalyzed peeling reactions. The high cellulose yield enables efficient production of cellulosic pulp, or a source for the second generation C6 sugars that do not compete with food production. Or the production of GVL solvent itself. Hemicelluloses extracted as sugars and are converted into furfural and various products therefrom. The third main biomass constituent, lignin, is extracted in sulphur-free form that finds uses in a number of emerging products.
The GVL process is a game changer with respect to business cases, too. The chemical recovery cycle of GVL process is a simple distillation process; in fact much simpler than the Kraft recovery cycle. This has a major impact on the capital cost which can be a decisive factor in business cases where vast quantities of feedstock needed for a Kraft mill are not available. In addition, GVL-fractionation process does not share Kraft process’ problems with silica containing non-wood feedstocks. Therefore, GVL process enables not only new products but also enables business cases in new regions with unutilized feedstock sources.
The FRACTION project is one step towards making the promises of GVL process a reality.
I am proud of being a member in a consortium which combines the best sides of academia and industry. Steering from the industry helps focus on products with highest business potential, and for industry being a member in a consortium allows the industry to assess the very latest stages of R&D and techno-economic evaluations. There are many challenges to be tackled but perhaps in the future the GVL process is enjoying similar status as the Kraft process today.
“Lasse Tolonen is a senior R&D specialist at Stora Enso specializing in chemical processes to fractionate biomass”