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This novel study presents an effective comprehensive life cycle assessment (LCA) of a novel sustainable carbon dioxide capture and utilization (CCU) system to co-produce alcohol ethoxylate (AE7), a valuable surfactant (a high-value chemical component of liquid detergents), and low-medium distillate range liquid fuel. Conventionally, AE7 is produced by reacting fatty alcohols with ethylene oxide from mostly fossil and marginally bio-based resources. This research develops novel AE7 production using carbon sources from flue gas of paper and steel industries, addressing a critical gap in the literature. The core process is Fischer-Tropsch (FT) synthesis using syngas formed by the reverse-water-gas-shift reaction, where recycled CO2reacts with H2. FT produces C11-C13 alkanes and a light-to-medium fuel co-product. The alkanes are converted into C12-C14 fatty alcohols through dehydrogenation, hydroformylation, and hydrogenation. Fatty alcohols react with ethylene oxide to form AE7. The yields (w/w) of AE7 and the fuel co-products are 3.7 % and 3.4 % for paper industry flue gas, and 8.0 % and 9.5 % for steel industry flue gas, respectively. Renewable (wind) electricity meets the hydrogen demand and electricity needs for the reactions, a total of 13.4 and 33.3 kWh/kg flue gas, respectively. The life cycle impact assessment includes global warming potential (GWP) and other impacts using ReCiPe, Impact+ , and Product Environmental Footprint methods. Baseline scenarios show GWP ranging from 2.2 to 3.6 kg CO2e/kg surfactant for conventional cradle-to-gate AE production systems. The new systems have GWP ranging 0.4–1.3 kg CO2e/kg flue gas (cradle-to-gate) using mass allocation. Meanwhile, the paper industry’s flue gas system has biogenic CO2, while the steel industry’s CO2is fossil-based. Considering the GWP reductions due to biogenic CO2contents, their overall GWP is 2.56 kg CO2e and 10.33 kg CO2e per kg of product (AE7 +fuel) (cradle-to-grave) using economic allocation. Thus, biogenic CCU is critical for the sustainable co-production of high-value surfactants and fuel.

Bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs) present numerous benefits for the removal and recovery of heavy metals from industrial and municipal wastewater. This study evaluated the life cycle environmental impact of simultaneous hexavalent chromium (Cr(vi)) removal and bioelectricity generation in a dual chamber MFC. Results indicate a global warming potential (GWP) of −0.44 kg carbon dioxide (CO2)-eq. per kg of chromium recovered, representing a total saving of up to 97% in comparison with existing technologies for the treatment of Cr(vi) laden wastewater. The observed savings in GWP (kg CO2-eq.) reduced to 61.8% with the removal of the allocated credits from the MFC system's life cycle. Of all the various sub-systems considered within the chromium waste treatment plant, the MFC unit and the chromium metal recovery unit had the largest impact in terms of GWP (kg CO2-eq.), non-renewable energy use (NREU) (MJ primary), and mineral extraction (MJ surplus). A statistical analysis of the results showed that an increase in chemical oxygen demand (COD) was associated with a reduction in GWP (kg CO2-eq.), NREU (MJ primary), and terrestrial ecotoxicity (kg triethylene glycol equivalents into soil (TEG soil)-eq.). The life cycle assessment (LCA) output showed a high sensitivity to changes in the materials and construction processes of MFC reactors, indicating the need for further research into sustainable materials for MFC reactor construction. The observed interaction effects of process variables also suggest the need for combined optimization of these variables. Analysis with other types of metals is also important to further demonstrate the practical viability of metal removal through MFCs.

Assessing how bioenergy projects translate into socioeconomic benefits is needed to demonstrate its value in industrial decarbonisation and sustainability strategies. This work presents a framework for bioenergy sustainability assessment wherein a set of indicators are selected, co-developed and weighted using a participatory approach. The framework integrates stakeholder identification, literature review and overlap analysis to derive an initial set of indicators used for participatory selection. The framework applied to bioenergy in community-based forestry in Mexico with participation of community and local stakeholders revealed sustainability indicator priorities and relevance in regards to occupational injury, illness and fatalities, training and/or education, use of renewable energy and household income (economic pillar); access to household electricity service, to municipal water supply, to sewerage service and to fuel, and female participation (social pillar); the loss of natural resources and grazing land, waste reduction for energy and sewage water treatment (environmental pillar). Indicators related to streetlighting were downplayed by the participants while forest fires, soil erosion, reduction of waste burning, and reduction of water use were indicators derived from the concerns expressed by the participants. The framework was useful for capturing stakeholders' relevance and priorities to make indicator selection more realistic in measuring the bioenergy impacts and co-benefits for local community. The framework using a participatory approach allows for validation with stakeholders across the scales (local, regional, and national) which can be applied to other bioenergy case studies. The framework is also a step towards an approach integrating bottom-up and top-down perspectives.

Driven by the need to develop a wide variety of products with low environmental impact, biorefineries need to emerge as highly integrated facilities. This becomes effective when overall mass and energy integration through a centralised utility system design is undertaken. An approach combining process integration, energy and greenhouse gas (GHG) emission analyses is shown in this paper for Jatrophabiorefinery design, primarily producing biodiesel using oil-based heterogeneously catalysed transesterification or green diesel using hydrotreatment. These processes are coupled with gasification of husk to produce syngas. Syngas is converted into end products, heat, power and methanol in the biodiesel case or hydrogen in the green diesel case. Anaerobic digestion of Jatrophaby-products such as fruit shell, cake and/or glycerol has been considered to produce biogas for power generation. Combustion of fruit shell and cake is considered to provide heat. Heat recovery within biodiesel or green diesel production and the design of the utility (heat and power) system are also shown. The biorefinery systems wherein cake supplies heat for oil extraction and seed drying while fruit shells and glycerol provide power generation via anaerobic digestion into biogas achieve energy efficiency of 53 % in the biodiesel system and 57 % in the green diesel system. These values are based on high heating values (HHV) of Jatrophafeedstocks, HHV of the corresponding products and excess power generated. Results showed that both systems exhibit an energy yield per unit of land of 83 GJ ha−1. The global warming potential from GHG emissions of the net energy produced (i.e. after covering energy requirements by the biorefinery systems) was 29 g CO2-eq MJ−1, before accounting credits from displacement of fossil-based energy by bioenergy exported from the biorefineries. Using a systematic integration approach for utilisation of whole Jatrophafruit, it is shown that global warming potential and fossil primary energy use can be reduced significantly if the integrated process schemes combined with optimised cultivation and process parameters are adopted in Jatropha-based biorefineries.