Major breakthrough can turn plant waste into cheap biofuels

14 Jan 2020

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A new discovery could help lessen our reliance on fossil fuels by turning plant waste into biofuels, such as ethanol, in a much cheaper way than before.

Among the many ways suggested to reduce humanity’s reliance on polluting fossil fuels is replacing them with biofuels. Now, researchers from Rutgers University have published a study to Green Chemistry showing they can produce these fuels from plant waste for a fraction of the cost of other methods.

Their approach uses an ammonia-salt based solvent that can rapidly turn plant fibres into the sugars needed to produce ethanol. Importantly, it works well at close to room temperature, unlike traditional processes.

Future Human

“Our pre-treatment system can slash – by up to 50-fold – the use of enzymes to [plant fibre] into glucose used to make bioproducts like ethanol,” said lead author Shishir P S Chundawat.

“Similar processes could greatly reduce the cost of producing biofuels from waste biomass like corn stalks and leaves.”

The solvent can also extract more than 80pc of the lignin in plant waste, which can be used to help upgrade valuable aromatic chemicals in the future, according to Chundawat.

This ability to break down plant fibres was key to the breakthrough. Corn stalks, leaves and other residue – called corn stover – have tightly packed cellulose microfibrils, which are tiny strands thinner than fibres.

These microfibrils are difficult to break down using enzymes or microbes, making it hard to turn many plant-based materials in biomass into biofuels or biochemicals. Over the past 150 years, researchers have tried several solvents to break down cellulose fibres, but most remain costly or require extreme pressures or temperatures to be effective.

It’s estimated that the ammonia-salt based solvent can convert cellulose into sugars at between 15pc and 20pc of the cost of making ethanol from biomass. The researchers said the next step will be to optimise the pre-treatment process for biomass like corn stover, solid waste and bioenergy crops such as switchgrass and poplar, which could be turned into fuels.

Colm Gorey was a senior journalist with Silicon Republic