Iowa State researchers have developed thermochemical technologies that efficiently produce sugars from biomass.
Naomi Friend/Bioeconomy Institute photo

Engineers have developed a way to make low-cost sugars from biomass - a discovery that has the potential to reduce the cost of producing biofuels.

“It looks like something you could pour on your pancakes,” says Robert Brown, an engineering professor at Iowa State University, Ames, Iowa, about a vial of dark, sweet-smelling liquid. “In many respects, it is similar to molasses.”

Brown, in fact, calls it “pyrolytic molasses” because it was produced by the fast pyrolysis of biomass such as corn stalks or wood chips. Fast pyrolysis involves quickly heating biomass without oxygen to produce liquid or gas products.

“We think this is a new way to make inexpensive sugars from biomass,” says Brown.

Those sugars then can be further processed into biofuels. Brown and other Iowa State researchers believe pyrolysis of lignocelluslosic biomass has the potential to be the cheapest way to produce biofuels or biorenewable chemicals.

Brown and Iowa State researchers presented their ideas and findings during tcbiomass2011, the International Conference on Thermochemical Conversion Science in Chicago Sept. 28-30. Brown addressed the conference with a plenary talk describing how large amounts of sugars can be produced from biomass by a simple pretreatment before pyrolysis. He also explained how these sugars can be economically recovered from the products of pyrolysis.

Brown highlighted thermochemical technologies developed by 19 Iowa State research teams, including processes that:
  • Increase the yield of sugar from fast pyrolysis of biomass with a pretreatment that neutralizes naturally occurring alkali that otherwise interferes with the release of sugars.
  • Prevent burning of sugar released during pyrolysis by rapidly transporting it out of the hot reaction zone.
  • Recover sugar from the heavy end of bio-oil that has been separated into various fractions.
  • Separate sugars from the heavy fractions of bio-oil using a simple water-washing process.
The work has been supported by the ConocoPhillips Biofuels Program at Iowa State.

“The Department of Energy has been working for 35 years to get sugar out of biomass,” Brown says. “Most of the focus has been on use of enzymes, which remains extremely expensive. What we’ve developed is a simpler method based on the heating of biomass.”