Rice straw-to-ethanol research project gets underway

Making biofuel from rice straw would turn what is usually burned into a cash crop (Photo: Aston University)

A team at Aston University in Birmingham, UK, is set to tackle the problem of converting rice straw into biofuel.

The research will be led by Dr Alfred Fernandez-Castane, senior lecturer in biochemical engineering and principal investigator at the Energy and Bioproducts Research Institute at Aston University. Marie Curie fellow Dr Longinus Igbojionu will also take part.

Current biofuel production largely relies on crops such as sugarcane and sugar beet, with related concerns as to the balance between food and fuel crops.

Dry matter such as rice straw is seen as a better alternative as it is usually treated as an agricultural waste by-product that is largely burned in the field.

The two-year project, which goes by the catchy title of ‘An integrated approach to ethanol production from rice straw via microwave-assisted deep eutectic pretreatment and sequential cultivation using Candida tropicalis and Saccharomyces cerevisiae’ will explore cleaner and cost-effective methods to extract energy-containing molecules from rice straw.

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 next is to develop novel biotransformations 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 will help contribute to combating 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.

According to statistics from the World Bank, rice serves as the staple food crop for more than 3.5 billion people around the world. It is put forward that for every additional one billion addition to the global population, a further 100 million metric tonnes of rice will need to be produced each year.

The International Energy Agency states that demand for biofuels through 2027 is set to increase by about 20%. The use of rice straw would help to reduce dependence on imported oil, while reducing greenhouse gas emissions in countries which could benefit from a solution.

The research at Aston University is set to be completed in November 2025.