Optimization of bacterial biorefineries for sustainable biodiesel production and flue gas reduction: a holistic approach to climate change mitigation and circular economy†

The primary obstacles to addressing the current climate change problem include a rise in worldwide energy consumption, a restricted availability of fossil fuels, and the escalating carbon emissions associated with fossil fuels. Consequently, there is a pressing need to investigate sustainable alternatives to fossil fuels. Biorefineries present a potentially viable avenue for the sustainable production of fuel, as they employ a range of technologies to convert biomass into biofuels. This research aims to examine the cultivation of bacterial biomass and biodiesel production using a biorefinery approach. This process achieves a removal efficiency of 96, 93, and 98% for CO₂, SO_2, and NO, respectively, and a bacterial biomass of 274 g cultivated in a 20 L integrated bioreactor. The biomass entails extracting lipids (58% w/w) to generate biodiesel (91% w/w). The metabolic pathway followed by bacteria to reduce flue gas and produce lipids was analyzed to improve the production of lipids and biodiesel. A life cycle assessment was performed to assess the environmental impacts during the process. Implementing alternative and safe chemicals can potentially mitigate the adverse effects of processes and GWP100. The techno-economic analysis aimed to systematically examine the capital investment required to set up a bacterial biorefinery as compared to conventional fuel refineries. The findings indicated that the bacterial biorefinery had a net present value of $193 per litre of biodiesel produced. A bacterial biorefinery holds promise in fostering a circular economy characterized by sustainable practices and systems that aim to minimize waste, optimize resource utilization, and encourage the reuse and recycling of materials.