Currently the production of biofuels mainly relies on sugar crops such as sugarcane and sugar beet, which raises concerns about the competition between growing crops for food or fuel.
However, plant dry matter such as rice straw is seen as a better alternative to current crops because it doesn’t affect food security. Rice straw is often treated as an agricultural waste by-product and is removed by being burnt in the field.
The research is being led by Dr Alfred Fernandez-Castane, Senior Lecturer in Biochemical Engineering and Principal Investigator at the Energy and Bioproducts Research Institute (EBRI) at Aston University, alongside a Marie Curie fellow, Dr Longinus Igbojionu.
Their two-year project, ‘An integrated approach to ethanol production from rice straw via microwave-assisted deep eutectic solvent pretreatment and sequential cultivation using Candida tropicalis and Saccharomyces cerevisiae’, will explore cleaner and cost-effective methods to extract rice straw’s energy-containing molecules.
Dr Alfred Fernandez-Castane said: “The problems envisaged with the conversion of rice straw to ethanol can be categorised into four main challenges and resolving each challenge will lead to a major advance on the current state of the art.
“The first is to develop pre-treatment conditions which will break down complex polymers thereby allowing the removal of lignin.
“The next is to investigate novel biomass pre-treatment technologies combining green solvents and microwaves and how different methods affect morphology, structure and crystallinity of biomass.
“The third challenge is to develop novel biotrasnformations using the yeasts Candida tropicalis and Saccharomyces cerevisiae to convert sugars into ethanol efficiently.
“These three challenges will lead to the fourth scientific challenge, which is to make the process sustainable and scalable, such as recycling the wastewater created and even the possibility of using the by-product of yeast for animal feeds.”
The team believes that the research, which will come to an end in November 2025, will help contribute to combatting global warming and decreasing avoidable deaths by protecting global food security, minimising CO2 emissions by reducing the burning of straw and decreasing the farmland needed for growing energy crops.