Driven by a range of sustainability challenges, e.g. climate change, resource depletion and expanding populations, a circular bioeconomy is emerging and expected to evolve progressively in the coming decades. South Africa along with other BRICS countries (Brazil, Russia, India and China) represents the emerging bioeconomy and contributes significantly to global sugar market. In our research, South Africa is used as a case study to demonstrate the sustainable design for the future biorefineries annexed to existing sugar industry. Detailed techno-economic evaluation and Life Cycle Assessment (LCA) were applied to model alternative routes for converting sugarcane residues (bagasse and trash) to selected biofuel and/or biochemicals (ethanol, ethanol and lactic acid, ethanol and furfural, butanol, methanol and Fischer–Tropsch synthesis, with co-production of surplus electricity) in an energy self-sufficient biorefinery system. Economic assessment indicated that methanol synthesis with an internal rate of return (IRR) of 16.7% and ethanol–lactic acid co-production (20.5%) met the minimum investment criteria of 15%, while the latter had the lowest sensitivity to market price amongst all the scenarios. LCA results demonstrated that sugarcane cultivation was the most significant contributor to environmental impacts in all of the scenarios, other than the furfural production scenario in which a key step, a biphasic process with tetrahydrofuran solvent, had the most significant contribution. Overall, the thermochemical routes presented environmental advantages over biochemical pathways on most of the impact categories, except for acidification and eutrophication. Of the investigated scenarios, furfural production delivered the inferior environmental performance, while methanol production performed best due to its low reagent consumption. The combined techno-economic and environmental assessments identified the performance-limiting steps in the 2G biorefinery design for sugarcane industry and highlighted the technology development opportunities under circular bioeconomy context.

The overwhelming concerns due to over exploitation of fossil resources necessitate the utilization of alternative energy resources. Biodiesel has been considered as one of the most adaptable alternative to fossil-derived diesel with similar properties and numerous environmental benefits. Although there are various approaches for biodiesel production, development of cost-effective and robust catalyst with efficient production methods and utilization of a variety of feedstock could be the optimum solution to bring down the production cost. Considering the complexity of biodiesel production processes, process design, quantitative evaluation and optimization of the biodiesel from whole systems perspectives is essential for unlocking the complexity and enhancing the system performances. Process systems engineering offers an efficient approach to design and optimize biodiesel manufacturing systems by using a variety of tools. This review reflects state-of-the-art biodiesel research in the field of process systems engineering with a particular focus on biodiesel production including process design and simulation, sustainability evaluation, optimization and supply chain management. This review also highlights the challenges and opportunities for the development of potentially sustainable and eco-friendly enzymatic biodiesel technology.

Globally, one in nine people suffer from undernourishment with evidence that this number is increasing. Additionally, due to the projected 50% increase in global population, the demand in worldwide animal-sourced protein is expected to double by 2050. Furthermore, not only are global animal protein supply chains susceptible to the effects of climate change, but they are also a significant contributor to greenhouse gas emissions and require large areas of arable land. Single cell proteins (SCPs) are an alternative protein source that offer a potential route to reduce the environmental impact of global protein consumption. One such SCP is Fusarium venenatum, which is a strain of mycoprotein widely sold under the brand name Quorn and is produced through the fermentation of the microorganism on glucose. However, this glucose still has a significant arable land-use burden associated with it. In order to mitigate this burden, sugars derived from agricultural lignocellulosic residues could be used, however, additional processing steps are required. In this work, exploratory research on fermentation of F. venenatum on sugars derived from lignocellulosic residues is presented. The food-grade ionic liquid [Ch][HSO₄] was employed in combination with food-grade Celluclast 1.5L to extract glucose from rice straw residues, which resulted in an overall glucose yield of 42.4% compared to using non-food certified ionic liquid [TEA][HSO₄], which yielded 92.8%. Based on these results, a Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA) were conducted after synthesising a biorefinery process model. TEA modelling outcomes highlighted that the crude mycoprotein paste product could be produced for $5.04 kg⁻¹ ($40.04 per kg-protein). By conducting a retro-techno-economic analysis, it was shown that there is reasonable scope for reducing this price further by improving saccharification yields and utilising feedstocks with high cellulose contents. Furthermore, LCA results demonstrated significant sustainability benefits of lignocellulosic-derived mycoprotein, with greenhouse gas emissions less than 14% that of protein from beef. However, the most significant advantage of this technology is the minimal dependence on arable land compared to animal-sourced and plant-sourced proteins such as beef and tofu.