Brewing a better biofuel

Biomass is a diverse complex polymer comprising three key components; cellulose, hemicellulose and lignin. Cellulose and hemicellulose consist of long chains of sugars nestled within lignin, a complex polymer of alcohols, acting as a binder to provide structure and rigidity to the biomass. What makes this woody biomass strong, also makes it difficult to breakdown. So the first step in any second-generation biofuel production is to deconstruct the polymeric mess of lignin and loosen its structure. Traditionally, and in today´s up and coming commercial ventures, this pre-treatment takes place either using mechanical comminution, steam or acids and alkalis to break down the material, aiding enzyme access to cellulose and hemi-cellulose. While these processes are effective, they consume vast amounts of energy and are expensive. Research is currently underway to improve the genetics of the feedstock so it´s more readily digestible, but a promising pre-treatment process is to use ionic liquids. These powerful solvents are more effective at breaking down biomass at lower temperatures and can be recovered. But cost is a massive issue, so research is underway worldwide to develop cheaper, more recoverable versions. Once the cellulose and hemi-cellulose is accessible, enzymes are used to hydrolyse these long polymer sugar chains to monomers, ready for industry-standard fermentation to ethanol. Again enzymes are expensive but rapid development means costs are plummeting.