The Fraunhofer Center for Chemical-Biotechnological Processes (CBP) has a very different take on using wood. Refine it into the main component parts similar to what is done with crude oil.
Fraunhofer working jointly with 12 partners from industry and research institutions recently developed a process that enables them to use 80 to 90 percent of the wood substance - moreover, the lignin is sulfur-free.
The basics have been used in the paper industry for decades in the production of cellulose or pulp, for wood-based paper production. Only 50% of the wood is a viable substance, the rest has been converted into energy, burned and used as bio energy process heat. The problem in the paper production process is the lignin portion is contaminated with sulfur compounds typically used as a tool to break up the wood. That means for many products, lignin is out of the question. Lignin mixed with sulfur cannot be post-processed in systems that involve catalysts.
Fraunhofer realized to make raw materials like wood accessible to certain sectors in the chemicals industry – use the same approach as an oil refinery. Similar to a petroleum-based refinery, they fractionate the raw materials into their basic components, and then send each component to its optimal application.
Waste wood, divided into the lignin and cellulose, would serve as a raw material source. The cellulose-based carbohydrates could replace petroleum used to make plastics, fuels and other chemicals.
Dr. Moritz Leschinsky, group manager at CBP explains, “We break down the wood into its primary components, lignin and cellulose, by boiling it in water and alcohol at high temperatures and under high pressure – sort of like a pressure cooker.” The lignin dissolves in the fluid, while the cellulose remains solid. In another step, the scientists extract the lignin from the fluid.
The extracted cellulose serves as a raw material for biosynthetics: Once broken down into basic components, i.e. sugars, the researchers then produce the necessary monomers to build the chemicals for making products. The lignin is used as a biomaterial for example as a binding agent for the wood industry.
Leschinsky takes up the explanation, “The main challenge we’re facing is how to design the process affordably while sparing resources. For example, we need to close the cycle for the ethanol and water and recover these substance.”
The pilot plant opened together with the new CBP building on October 2, 2012 in Leuna, Germany where the researchers intend next to apply their laboratory findings to large quantities of wood. The new pilot facility is truly one-of-a-kind through all of Europe, each week it can break down up to a ton of wood into its individual constituent parts, using organic solvents in the refinery.
In the laboratory, the Fraunhofer scientists have largely completed their developments for various types of wood. Now they want to upscale the process and make it more energy-efficient. They expect that within the next five years, the process will be ready for use in industrial production facilities.
The Fraunhofer perspective is very interesting and has exceptional potential economics. Assuming the ethanol and water are fully recycled and the recovery leads to 80 to 90 percent useful carbohydrates form the wood, the team will have a leading process contender.
Just what to do with the clean lignin is the opportunity – problem- challenge. Its very tough stuff and the prospects, in a clean near pure form, the ideas will come fast and furious when the volume builds up. One notion would be to charcoal the lignin to extract the heat energy and return the bulk of the nutrients back to the soil.
The Fraunhofer idea is certainly an insightful and innovative view of the seemingly perplexing cellulosic fuel problem that looks like a good solution.