Bio4Energy researchers have started to carve out a niche for themselves as specialists in dealing with recalcitrant biomass, be it from coniferous trees, agricultural residue or organic waste, a string of recent research results would suggest. While some work to control the organic content of the biomass, others break ground on biomass combustion where the focus is rather on ash chemistry and emission control. In the latter case, the focus is on the inorganic content of biomass.
Looking first at the organic biomass content, on the Bio4Energy Biochemical Platform they lead the world in solving thorny problems to do with the breakdown of wood or forestry residues from spruce trees for the production biofuels and "green" chemicals, a recent evaluation of Bio4Energy 2010-2014 has shown.
Going hand in hand with recent work by these biochemists to demonstrate a new method for large-scale bioethanol production—which makes use of a residual stream previously thought of as an environmental problem—new separation processes that make the wood release its sugars more easily have been put forward and compared by the scientists, who are specialised either in industrial biotechnology or catalytic processes and, in particular, the breakdown of biomass using ionic liquids. (Click on the 'Research' menu heading of this website to access recent Scientific Articles.)
In a recent article in the BMC Biotechnology scientific journal, they explain that, "Lignocellulosic biomass is highly recalcitrant and various pre-treatment techniques are needed to facilitate its effective enzymatic hydrolysis to produce sugars for further conversion to bio-based chemicals. Ionic liquids (ILs) are of interest in pre-treatment because of their potential to dissolve lignocellulosic materials including crystalline cellulose.
"The ability of ILs to dissolve lignocellulosic biomass under gentle conditions and with little or no by-product formation contributes to making them highly interesting alternatives for pre-treatment in processes where high product yields are of critical importance", the Bio4Energy scientists conclude.
Combing different types of biomass for hassle-free, environmentally correct CHP
Last but not least, researchers on the Bio4Energy Environmental and Thermochemical Platforms have been investigating whether, by combining different types of waste such as agricultural residue or even organic municipal waste sludge with "biosolids" such as wood from forestry residues, a biomass-based fuel for heat and electricity production may be invented which not only burns clean, but also does not cause corrosion of the combustion reactor used.
The environmental scientists' contention was that, by examining the contents of various types of biomass waste—such as oat husks or rotted biomass from municipal waste sludge—and pairing them with solid biomass, plus capturing and separating out some of the ash mineral content—phosphorus, notably—they would come up with a fuel which did not damage the combustion reactor and produced less environmentally-detrimental emissions when burned, compared with just burning one type of residue without previous processing.
"There is a fairly elegant method for doing this that we have tried in full [industrial] scale", Skoglund said, and which "no one else is using".
The naturally occurring element phosphorus is both an essential nutrient for all living organisms and a threat to soils and water when released in excess as it is by modern society. If it could be captured before it gets in the environment—in the biomass combustion process, in this case—and reused, this would not only serve to avoid eutrophication, but also help remedy a global situation of phosphorus becoming in short supply as fertilizer. Experts have warned that the world is going toward such a situation of shortage and thus of hampered food production.
Seeing it from his perspective as a scientific researcher interested in thermal combustion processes, Skoglund said: "Phosphorus has proven to be an important marker for the way in which the inorganic content, the ash, of biomass behaves.
"By understanding the behavior of the ash we can increase the use of tough biomass. Our long-term goal is to understand the reactions of the inorganic contents during fuel combustion, so that dangerous substances from the part of the ash rich in phosphorus may be removed already during the combustion".
But where does that leave 'co-combustion'?
"By knowing which compounds we would like for there to be forming when biomass is burned we can choose what types of biomass to mix together. This gives us great possibilities to increase the use of renewable energy in society while, at the same time, [extracting and] reusing nutrients via the ash", according to Skoglund.
"The difficult part is to convince industry to try new types of biomass and fuel blends. But we have had the advantage of running our projects in full scale", he added, with reference to technology trials his group performed at the premises of industrial partners 100 Megawatt facilities for combined heat and power production (CHP).
"This has taught us that co-combustion is the future. We have seen that... we can burn several types of biomass residue together and with a nice outcome, instead of burning them one at a time and produce a bad result".
Notes for editors:
A press release in Swedish signalling Nils Skoglund's thesis defence 5 June was issued by Umeå University in cooperation with Bio4Energy.