ARS and OSU researchers develop process for biobutanol from sweet sorghum bagasse

February 14, 2022 |

In Ohio, a team of Agricultural Research Service (ARS) and Ohio State University (OSU) scientists has devised a procedure for making bio-butanol from sweet sorghum bagasse.

Bio-butanol derived from cellulosic sugars in agricultural wastes is appealing because of its potential to lessen the reliance on gasoline and other nonrenewable fuels. Bio-butanol, along with ethanol, is also considered a cleaner burning alternative gasoline. However, bio-butanol can be transported in existing pipelines and is less corrosive to internal combustion engines than ethanol. Bio-butanol also packs 33 percent more energy per gallon and is easier to blend with gasoline. It also can be catalytically upgraded to bio-jet fuel (sustainable aviation fuel).

In particular, the researchers set their sights on harvest or processing wastes like corn stover, barley and wheat straw, lesquerella presscake and most recently, sweet sorghum bagasse. To help them, the researchers recruited hardy new strains of bacteria such as Clostridium beijerinckii P260 to ferment the wastes’ cellulosic sugars inside specialized vats, called bioreactors.

A key advance the team made was combining what had previously been a series of separate steps into a single streamlined process—namely, the release of the wastes’ cellulosic sugars, their fermentation into bio-butanol and the removal of this four-carbon alcohol (along with acetone and ethanol) from the bioreactor. This also helps protect the hardworking bacteria inside.

In laboratory-scale experiments, the microbes produced 23 grams of bio-butanol from 160 grams of bagasse. This corresponds to production of 46 gallons of butanol from 1 ton of sweet sorghum bagasse. Additionally, it also produces 31 gallons of acetone and ethanol per ton of this feedstock that can be used as valuable chemicals. The researchers used a solid concentrated form of bagasse (16-22 percent) that required a smaller-sized bioreactor and used about 50 percent less energy than producing bio-butanol from wheat straw, another waste they experimented with.

Category: Research

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