So far, a lot of efforts have been put in life cycle assessments (LCA) of bioethanol production. There are many works that have assessed bioethanol production in different points of view to illustrate the environmental impacts. This study reviewed former LCA studies on bioethanol produced from various biomass resources by considering the effect of methodological components, technical pathways and feedstock provision on the result of LCA studies. The review evaluated 48 papers published 2002–2021 with a focus on studies that included a complete set of environmental impact categories. However, due to lack of harmony among studies, comparing the LCA results was challenging but the review indicated that the final results of studies are influenced by LCA methodological components, such as system boundary, functional unit, etc. Around 80% of the reviewed papers show the reduction in global warming potential, while contrary results have been found about increasing acidification, eutrophication and photochemical oxidant formation impact categories because of the feedstock provision. Regarding technical aspects, results from the review revealed that most of the studies considered the pre-treatment as a crucial step in bioconversion processes. Despite several LCA studies of bioethanol production, there is still low attention given to uncertainty analysis in the publications.

Among the different alternatives for the production of biofuels, food waste could be a favorable bioenergy source. Using food waste as a feedstock has the potential to meet the expectations of the second generation of biofuels, in terms of environmental savings and revenue-generation, and which, along with other valuable co-products, can contribute to biorefinery profits. This study aimed to investigate the early stages of life-cycle assessment (LCA) for restaurant food waste processed into bioethanol, biomethane, and oil, split over different scenarios. Based on a life cycle inventory analysis, the environmental impacts were assessed using an IMPACT 2002+ methodology. The characterized impacts were then normalized against the average impacts, and the normalized results were weighted and aggregated to provide single score LCA results. The overall findings showed that electricity consumption and condensates included VFAs, as well as enzymes, yeast, and n-hexane, were the main contributors to the environmental burdens in all impact categories. Considering the sensitivity analysis, the results demonstrated that the enzyme dosage loading in the hydrolysis process and n-hexane utilization in the fat extraction process can change the environmental performance, along with the process efficiency. This study can provide an approach to foresee environmental hotspots in the very early developmental stages of food waste valorization into biofuels, and for highlighting drawbacks connected to the implementation of conversion processes at pilot and industrial scales.

Biowaste valorization is a means for tackling resource depletion and climate change, which gives rise to environmental benefits and economic growth. One of the most known technological routes to convert biowaste into bioproducts is pyrolysis, which may conduct with and without catalyst application. The purpose of this study was to investigate an early-stage life-cycle assessment (LCA) for catalytic intermediate pyrolysis to valorize rapeseed meal, split over the scenarios using ZSM-5 and zeolite Y catalysts. Four selected environmental impact categories were assessed by IMPACT 2002+ methodology. The results revealed that the ZSM-5 catalytic pyrolysis led to bigger environmental impacts than the pyrolysis utilizing zeolite Y in all compared impact categories except global warming. The scenario that involved zeolite Y had around 20% GHG intensity greater than ZSM-5 pyrolysis. The bulk of GHG emissions mostly involved CO₂ and methane generated from electricity consumption, which was provided by fossil resources. Applying ZSM-5 in the pyrolysis increased environmental burdens in non-renewable energy, respiratory inorganics, and terrestrial ecotoxicity by 140.88 MJ primary, 8.83 × 10⁻³ kg PM_2.5 eq. and 125.63 kg TEG soil, respectively. The major driving factor of high value in mentioned categories was the manufacturing process of the ZSM-5 catalyst by utilizing natural gas and chemicals, such as phosphorus trichloride, sodium hydroxide and sodium silicate. Given that catalysts can play a substantial role in the emissions resulting from bio-based products, hence LCAs of pyrolysis should consider the potential influence of catalysts in the valorization processes. This study can predict environmental hotspots in the early stages of bio-waste valorization and show the potential defects of implanted biorefinery at pilot/industrial scales.

Despite the European Green Deal’s pursuit for a resource-efficient economy, industry remains largely dependent on linear material use. This paper presents an analysis of rapeseed meal valorisation through pyrolysis to unlock its circular economy potential, set against the backdrop of the European Green Deal’s ambition for a resourceeffective economy. The study investigates the transformative role of converting agro-industrial waste into valuable products. Through strengths, weaknesses, opportunities, threats and techno-economic analysis, the feasibility and opportunities of rapeseed meal pyrolysis are examined. An overview of the economic performance of a pyrolysis plant with a capacity of 32,000 Mg per year is presented. Based on the results, the plant is economically viable, as it presents a positive net present value and an appropriate internal rate of return for the condition considered. The annual cash flow amounts to EUR5.05 mln and the initial investment is EUR25.24 mln, which demonstrates the plant’s ability to not only cover operational costs but also generate considerable profits. Additionally, despite the existing challenges in scaling up from laboratory-scale to industrial application, strategic approaches are proposed to overcome obstacles. Overall, this study underscores the significance of rapeseed meal valorisation as a pathway toward a more resilient, resource-efficient and sustainable future.