In his dissertation, Senior Scientist and M.Sc. (Eng.) Kristian Melin of VTT Technical Research Centre of Finland has developed a modelling and evaluation method for identifying which biorefinery processes – of those being considered for development –will use raw materials most efficiently, reduce greenhouse gas emissions the most, or be most economical. The method can also accelerate the development of new bio-economic processes from laboratory to production scale.
There has been public discussion of how much and what kind of wood raw material can be used sustainably for biorefinery purposes in Finland. Sustainable wood raw material is available in limited amounts and should be used efficiently. Fuels made from wood unfit for other processing would be more environmentally friendly than fossil fuels, but tend to have even higher production costs.
The more efficient biorefinery processes discovered via the new method are based on separate processing of carbohydrate and lignin components extracted from wood. Such processes could make biorefineries more economical and more efficient in their use of raw materials.
The study showed that integration of the biorefinery process with a paper and pulp mill or separate plant would be the ideal solution, since this would enable the use of superfluous heat, wood bark and lignin extracted from the chemical cycle.
Of the processes studied, the highest energy efficiency ratio, 72.5%, was achieved with the novel hydrocarbon production process developed as part of the dissertation work, which uses external heat. The energy efficiency to biofuel product is a few percentage points higher than for the typical synthetic methane production process and around twelve percentage points higher than for methanol production. In addition, production costs were lower and greenhouse gas emissions were reduced more in the developed process.
The development of biorefinery processes has been time-consuming and somewhat uncertain
It can traditionally take over ten years and cost tens of millions of euros to develop a new biorefinery processing from laboratory to production. The number of process and raw material alternatives pose a challenge during the development of new biorefinery processing techniques. When choosing between these alternatives, at least the production costs and environmental impacts should be considered, which can be difficult to evaluate due to lack of data during the early stage.
Process alternatives explored during the early stage may have to be chosen on the basis of insufficient information, but the wrong choice could delay development for years, or result in a non-optimal process. If the wrong process is selected, changing it at a later stage can be slow and expensive.
The new modelling and evaluation approach developed for the dissertation has been used for the development of new, more efficient biorefinery processing concepts. The efficiency of the processes developed have yet to be confirmed in large-scale trials, since they are still at the early development stage. VTT is exploring many of the biorefinery processes studied in the dissertation, evaluating their technical-economic viability and sustainability in the early stages of development, while helping customers to select the right processes.
The dissertation, "Design and evaluation of biorefinery concepts" by Senior Scientist Kristian Melin was examined at Aalto University on 19 January 2018.
The dissertation can be found online at: http://www.vtt.fi/inf/pdf/science/2017/S158.pdf