Researchers develop new method to produce ethanol from grasses
Researchers from the Indian Institute of Technology Kharagpur (IITK) have found that zero-cost materials such as grass and water hyacinths can be converted into large quantities of the biofuel, cellulosic ethanol. Using a method named pore-scale phenomena, the plants can be used to increase the amount of fermentable sugars and bioethanol from hemicellulose, a naturally occurring polymer found on plants’ cell walls. Hemicellulose has not been used widely in biofuel production, as until now the chemical reactions were only able to release a quarter of the soluble sugars needed for ethanol production.

Zero-cost materials such as water hyacinth and grass have the potential can yield a high percentage of biofuel, Indian researchers have discovered.

Research conducted by a team from the Indian Institute of Technology Kharagpur (IITK) indicates that pore-scale phenomena can be used to increase the yield of fermentable sugars and bioethanol from hemicellulose.

Water hyacinth, a free-floating and highly invasive perennial, contains up to 50% hemicellulose, present as natural polymers along with cellulose on plant cell walls.

The IITK research assumes that to produce a commercially viable biofuel, the traditional cellulosic ethanol must be supplemented with hemicellulosic alcohols.

Hemicellulose has so far been mostly ignored in biofuel production as surface reactions are capable of releasing only a quarter of the soluble sugars for ethanol production.

But the team at IITK has found out that to quickly produce soluble sugars from hemicellulose for the bioethanol industry, one has to look at its pores.

The average cellulose-hemicellulose ratio in plant cell walls is around 2:1, which – according to the study – suggests that biofuel productivity and cost-effectiveness could be boosted by more than 50% if the hemicellulose could be reasonably utilised.

Simultaneous production of cellulosic and hemicellulosic fuels from the same biomass source would considerably improve the combined net energy value (energy content of ethanol minus energy output) for cellulosic ethanol (about 21.5 MJ/lit).

"Increasing the polymer's porosity and swelling will eventually lead to increase in bioethanol," said Saikat Chakraborty, department and lead researcher of the Bioenergy Research group at IITK.