From Waste to Biofuels: Microbial Revalorization of Agro-industrial Left-Overs

Climate change and energy crisis are the biggest defining threats of our time. Energy demand is going up constantly while our fossil fuel reserve is steadily depleting, leading to an unprecedented rise in fuel prices. Our increasing dependence on fossil fuels has taken greenhouse gas (GHG) emissions and pollution to a record high, in turn, fuelling ecological degradation, global warming, weather extremes, natural catastrophe, and socio-economic disruption. Climate change has further been augmented by poor, inefficient, unsanitary waste management. Agricultural and industrial productions are going up concomitantly, arising from the need to nourish and support the ever-increasing global population. Such agro-industrial activities are generating huge amounts of garbage and residues that represent serious health hazards, environmental risks and economic burdens. The microbial revalorization of these agro-industrial wastes to generate biofuels can simultaneously address both the pressing issues of climate and energy emergencies. Organic lignocellulosic wastes such as left-over straw, bagasse, fruit and vegetable peels, tea and coffee residue, textile remains, woodchips, paper, kitchen garbage, and even livestock manure can all be used economically to produce sustainable, affordable, clean, and green alternative fuels like bioethanol, biobutanol, biodiesel, biogas, biomethane and so on. They can effectively reduce GHG emissions and help in waste management and climate mitigation. The microbial population plays a major role in this waste valorization process that involves various critical steps. However, such a biofuel industry is still in its budding stage and needs more extensive research and funding to improve waste conversion rate, net yield, and cost-effectiveness.