Finding the Value In Lignin

Sweden’s University of Borås researchers are finding values and ways to obtain them from the problematic plant residue lignin. Lignin, a substance considered as a waste product in biomass and ethanol production, would then reach its proper value as bio-oil in new products.

Lignin is a natural substance in biomass, but it is unwanted in processes like production of paper or ethanol. In those processes lignin is considered as waste, and is used as fuel in heat and power plants. At the University of Borås, Sweden, a team of researchers investigate methods to extract and refine lignin for better purposes than burning it.

While the commercial lignocellulose to ethanol plants use the lignin after pretreatment as biomass feedstock to heat and power the plants, in the Horizon 2020 project AGROinLOG, lignin will instead be transformed into bio-oil based products.

The researcher Swarnima Agnihotri has spent a year at the University of Borås refining the methods to extract the lignin from the lignin rich wheat straw.

She explains, “If biofuels are to become a reality, we need to realize the industrial potential of lignin and get more value from it,” she said. “Seeing the complexity and richness of its functional groups, there are various potential applications of lignin by converting it in a variety of value added products like high performance carbon fiber, bio-oil and vanillin, to name a few.”

The project aims at utilizing an agricultural residue, wheat straw, which is available in surplus in Sweden, and also in other European countries.

When asked for the press release what is there to gain for the society or industry from her part of the project, Agnihotri said, “Wheat straw lignin valorization will add value to the whole process, and in turn provide benefit to industry, as well as further insight in creating value from lignin, which has been considered a waste until now.”

Integration of lignocellulose based feedstock in ethanol plants is not new. There are a number of techniques already producing ethanol from lignocelluloses at commercial scale.

“It is the high investment costs and the low profitability of the process which needs to be addressed. The goal with this AGROinLOG project will be to see the possibilities of adding a high valuable byproduct, eg. bio-oil, to the whole production chain, and therefore increase the profitability of the process,” she said.

She addressed the project challenges by saying, “Finding a cost effective biomass fractionation process was a challenge. There is a lot of ongoing research on pretreatment for a better lignin extraction from lignocelluloses, but still the main challenge is to bring the cost down. The results are interesting and motivating.”

Next up: “Now, when we have optimized an efficient pretreatment process for effective lignin extraction from wheat straw, we will scale up the process, and the pure lignin obtained will be transformed into bio-oil through a hydrothermal liquefaction process done, that is, extracting liquid and get a concentrated oil. The bio-oil product obtained will be a high valuable byproduct since it can be further upgraded in refineries to obtain green chemicals and biofuels,” she said.

While this may seem out at the edge of research for new fuels to Americans, remember, the Europeans labor under astonishingly high taxes on fuels. They have a much larger costs basis to work with over there. Still there is a lot of lignin getting burned worldwide and if the Swedes can cut those costs and come up with the value added products the products will surely be welcomed.