At COP28 in Dubai, the overarching goal was to drive the global spotlight away from fossil fuels and make clean energy and its technologies the new standard. However, merely developing technology wasn’t the heart of the matter.
The focus was on ushering in the new standard in a fair and inclusive way by ensuring that developed and developing countries both have a stake in this change.
As COP29 approaches, the dialogue will focus on accelerating the phase-out of fossil fuels and boost commitments to renewable energy.
In the pursuit of cleaner and renewable energy sources, biofuels are conspicuous as a powerful alternative to fossil fuels. According to a report by India’s Ministry of Petroleum and Natural Gas, the country’s ethanol blending rate has seen a remarkable increase, from an average of 1.53% in the ethanol supply year (ESY) 2013-14 to 10.02% in ESY 2021-22, and 15% in 2024.
This jump highlights India’s commitment to biofuels boosting energy security and reducing carbon emissions.
Scientists have been exploring various biomass sources for bioethanol and biodiesel production, with lignocellulosic materials emerging as a key contender. And why not? Lignocellulose, which includes agricultural residues, wood and plant waste, is produced globally in quantities of about 181.5 billion tonnes each year.
Besides being an abundant and sustainable resource, it doesn’t compete with food crops, preventing the frequent food-versus-fuel conflict in other biofuel sources such as corn or sugarcane.
Second-generation biofuels, made from lignocellulosic materials, do more than just support the shift to sustainable energy – they also tackle waste management and circularity head-on. It’s a win-win situation for both energy and the environment.
Challenges in the biofuel production pathway
The downstream processing of lignocellulosic biomass – from pre-treatment to detoxification – presents several challenges. The breakdown of cellulose and lignin in the pre-treatment process to make sugars available for fermentation also produces toxic inhibitors.While these hurdles have been overcome significantly in aspects such as improving pre-treatment techniques and enhancing microbial tolerance, many aspects of the process are still being refined to improve efficiency and cost-effectiveness.
Technological advancements in certain physical, chemical and biological aspects to improve the production of biofuels from lignocellulosic biomass are briefly discussed here.
The ongoing research aims to render these steps more scalable and commercially viable, pushing the potential of lignocellulosic biofuels further.
Are there solutions on the horizon?
Picking the right raw material from the start can make fermentation easier, even before pre-treatment. The idea is to pick something that ’s “easy to unlock’, negating the need for harsh treatments to release the sugars for fermentation. Think of it like choosing softer recipe ingredients that cook faster.
Detoxification follows pre-treatment to eliminate harmful inhibitors. Some gentler methods for this include vacuum evaporation, which removes volatile toxins, or special filtration membranes to filter out toxins.
Alternatively, more chemically-intense methods tackle the problem by altering the molecular structure of inhibitors, rendering them less capable of disrupting fermentation.
Although effective, these methods can be a bit harsh and not always eco-friendly.
A smarter, more sustainable approach is to lean on nature. For example, we can use evolutionary adaptation, in which fermentative microbes are trained to thrive even in the presence of these inhibitors.
Yeast naturally breaks down sugars into ethanol during fermentation, but when inhibitors are present in the fermentation medium, it can slow this process.
Interestingly, if we expose yeast to these inhibitors in advance and allow them to “train” in tough conditions, they become better at handling those same inhibitors later on. It’s like preparing for a difficult situation by building resilience.
Tapping into microbes
Another approach is to tap into the natural abilities of certain microbes that can break down the inhibitory compounds present in the fermentation medium.
Some promising candidates include fungi and thermophilic bacteria, which can detoxify the environment using these inhibitors as sources of carbon and energy. However, in some cases, these helpful microbes also consume glucose, which reduces the ethanol yield and lowers the overall productivity.
As a workaround, enzymes such as laccases and peroxidases can be introduced. These enzymes specifically target and break down the inhibitors without glucose consumption, ensuring the fermentation process runs smoothly and ethanol yield remains high.
These nature-assisted techniques offer a greener, more practical way to solve the problem while generating minimum waste and allowing easy recycling of processed water.
Although several effective strategies adopt detoxifying fermentation, scaling them up for industrial biofuel production requires strong economic policies and support. These measures are essential to drive large-scale adoption, ensuring biofuels play a central role in achieving just energy transitions and meeting net zero carbon emission targets.
Monash is pioneering a path to a greener, smarter, more equitable and sustainable future, where emissions are lower, and the natural environment and humans thrive. We look forward to participating at COP29, where we aim to accelerate global action on sustainability, empowering diverse voices from across the Indo-Pacific and influencing superior policy outcomes across a broad range of issues.
AUTHOR
Harpreet Kaur, PhD student, Chemical and Biological Engineering, Faculty of Engineering, Monash University