Bio4Energy researchers have invented a process which could bring greater certainty of cost efficiency to industrial biorefineries that choose to base their operations on lignocellulosic input materials such as wood from spruce or pine trees.
Currently the U.S.A. and Italy are among few countries in the world to host industrial biorefineries for the production of ethanol based on cellulose via the biochemical conversion route using industrial enzymes and yeast. However, these biorefineries mainly use agricultural residue as feedstock in their operations.
While advanced bio-based production is seen as a great opportunity in several richly forested countries in the boreal belt, industrial operators there are up against a practical problem. A large part of the Canadian, Swedish and Finnish forest resource is made up of coniferous tree species whose woody composition is highly complex and requires harsh treatment before rendering its cellulose, hemicellulose and lignin components in separate parts, which is a requirement in most bio-based production. This harsh pre-treatment means toxic elements are left in the biomass slurry resulting from the process, whose impact must be reduced for efficiency to be achieved in the conversion step to fuels and chemicals.
A new invention by Bio4Energy researchers and partners is designed to tackle this very problem. In a techno-economic analysis, which is part of a package of four scientific articles, they outline a method for decreasing toxicity while increasing product yields by adding a certain chemical compound (sodium sulphite) in the conversion of the pre-treated biomass to bioethanol fuel, in this case.
The techno-economic evaluation showed that, by adding the sodium sulphite chemicals and thus conditioning or "detoxifying" the biomass-based slurries that resulted from the pre-treatment, less enzymes and less yeast were required to perform the conversion, while the yield of sugar to be transformed into biofuel rose.
"Secondly, [our method] is compatible with enzymatic saccharification and fermentation. The problem with many detoxification methods is that they have to be done as a separate step. Here you can combine it… [in] one step with the enzymatic saccharification and microbial fermentation", Jönsson went on;
"A third thing is the cost for this treatment… This is a way that is realistic to do in industrial scale".
Sodium sulphite is already in use as an additive in the pulping and textile industries, but is has not previously been added as a reducing or detoxifying agent in biofuel making on an industrial scale (for bulk production).
The new process including its combined detoxification and conversion step has been tested with good results at the Biorefinery Demonstration Plant at Domsjö Fabriker industrial complex at Örnsköldsvik, Sweden.
"It decreases the investment risk if you have a process based on softwood", such as spruce or pine, Jönsson concurred.
Collaborators on this project/package of articles:
Umeå University, Sweden
Leif Jönsson - Bio4Energy Biochemical Platform (leader)
Carlos Martín Medina - Bio4Energy Biochemical Platform
SP Processum, Sweden
Björn Alriksson, SP Processum
SEKAB E-Technology, Sweden
Umeå University and Bio4Energy issued a press release retelling the content of this news item.