Life cycle energy-carbon-water footprints of sugar, ethanol and electricity from sugarcane

Resources time footprint indicator extension for evaluating human interventions in provisioning ecosystem services supply

The growing emphasis on ecosystem services (ES) has enhanced evaluation of their capacity. However, intensive human intervention in the provisioning ecosystem service (P-ES) supply driven by widening spatial gaps between supply sources and demand locations, compromises the long-term ES supply potential. The Resources Time Footprint (RTF) indicator provides numerical insights into these impacts in the form of occupancy rates by comparing resource utilization to allocated capacities over a person's lifespan. Nonetheless, its applicability to major P-ES is currently restricted due to the lack of water and water pollutant occupancy rates concepts. This study attempts to broaden the scope and robustness of RTF by introducing these missing aspects for enhanced P-ES management. Furthermore, by evaluating changes in RTF value around technological and social dynamics, resources requiring management interventions are identified. The extended RTF's potential is finally demonstrated through case studies involving consumable rice, water flow utilized for generating electricity via hydropower (HP), and sugarcane yielding consumable sugar and molasses with bagasse used to generate electricity. Based on prevailing resource conditions, all cases exhibited resource utilization within the allocated capacity. However, potential strain on specific resources such as land and water use in rice (24.63 and 18.69 years), copper in HP (8.46 years), and land and phosphate-potash minerals use in bagasse (22.66 and 23.56 years) highlights the need for interventions to ensure sustained benefits. The precise influence of water and water pollutants is inherently case and location specific; however, this study emphasized the necessity of integrating water use and availability factors into rice and HP supply-flow assessments. Overall, the enhanced RTF proved to be replicable across P-ESs, quantifying pressures, and guiding management strategies to maintain nature's regenerative capacity while meeting human needs.

Life cycle assessment for evaluation of novel solvents and technologies: A case study of flavonoids extraction from Ginkgo biloba leaves

Innovative solvents such as deep eutectic solvents (DESs) and process intensification technologies assisted by ultrasound have been demonstrated to be promising pathways for enhancing solid-liquid extraction. Nevertheless, quantitative and systematic knowledge of their environmental impact is still limited. In this work, a case study of flavonoids extraction from Ginkgo biloba leaves was evaluated by using life cycle assessment (LCA) for comparison of three extraction scenarios. The first used DES as extractant (DESE), and the other two adopted ethanol, including heat reflux extraction (HRE), and ultrasound-assisted extraction (UAE). Among eight key midpoints investigated, all these from UAE were 10.0 %-80.0 % lower than from DESE and HRE except water consumption. The UAE was the eco-friendliest option due to its higher extraction yield, shorter duration and lower solvent consumption. The DESE exhibited the lowest water consumption, the highest freshwater ecotoxicity and human carcinogenic toxicity, while HRE had the highest impacts for the other 6 midpoints. Moreover, solvent production was the key contributor for all the categories. The standardized sensitivity analysis showed that the overall environmental footprint can be further decreased by 15.4 % for DESE pathways via substituting choline chloride/glycerine with choline chloride/ethylene glycol. Furthermore, all pathways using DESs had higher standardized impacts than those employing ethanol from sugarcane or wood. Replacing ethanol from maize with other feedstocks can significantly lessen the overall impacts, among which the UAE using ethanol from sugarcane demonstrated the least environmental impacts. The promotion of DESs as "green and sustainable" alternative to traditional solvents requires careful consideration.

Uncovering the energy-carbon-water footprint of waste rubber recycling: Integrated environmental and economic perspectives

The commitment to waste management has gained increasing momentum as global waste generation continues to skyrocket and threaten the environment. However, detailed assessments and clear insights remain absent to address the global waste utilization conundrum. This study evaluated the impact-oriented energy, carbon, and water (ECW) footprints of three typical scenarios for a waste recycling activity (i.e., waste rubber recycling) from environmental and economic dimensions, and explored key factors, nexus characteristics, and optimization measures. Results indicated that the rubber powder as an asphalt modifier scenario had a 93% greater environmental impact and 87% higher economic cost compared with the pyrolysis and reclaimed rubber production scenarios. Key processes, such as direct processes, electricity generation, and transportation, were identified as the major contributors to the ECW footprints, with the internal costs of raw materials, equipment, and taxes coupled with the external costs of human health dominating the economic impact. The nexus analysis results highlighted the urgent need to optimize the energy system for waste rubber recycling. Greening the production process revealed the benefits, with natural additives mitigating 85% of the environmental burden and 97% of the external costs compared with conventional additives. Industrial green microgrids, clean energy generation, proximity waste management, and electrified transportation were explored to foster sustainable optimization of waste rubber recycling systems. Moreover, a joint tax-subsidy mechanism for rubber production-recycling systems can stimulate recycling-oriented product design and increase the motivation to recycle waste rubber.

Dissecting the features of TGA gene family in Saccharum and the functions of ScTGA1 under biotic stresses

Sugarcane is an important sugar and energy crop and smut disease caused by Sporisorium scitamineum is a major fungal disease which can seriously reduce the yield and quality of sugarcane. In plants, TGACG motif binding (TGA) transcription factors are involved in the regulation of salicylic acid (SA) and methyl jasmonate (MeJA) signaling pathways, as well as in response to various biotic and abiotic stresses. However, no TGA-related transcription factor has been reported in Saccharum. In the present study, 44 SsTGA genes were identified from Saccharum spontaneum, and were assorted into three clades (I, II, III). Cis-regulatory elements (CREs) analysis revealed that SsTGA genes may be involved in hormone and stress response. RNA-seq data and RT-qPCR analysis indicated that SsTGAs were constitutively expressed in different tissues and induced by S. scitamineum stress. In addition, a ScTGA1 gene (GenBank accession number ON416997) was cloned from the sugarcane cultivar ROC22, which was homologous to SsTGA1e in S. spontaneum and encoded a nucleus protein. It was constitutively expressed in sugarcane tissues and up-regulated by SA, MeJA and S. scitamineum stresses. Furthermore, transient overexpression of ScTGA1 in Nicotiana benthamiana could enhance its resistance to the infection of Ralstonia solanacearum and Fusarium solani var. coeruleum, by regulating the expression of immune genes related to hypersensitive response (HR), ethylene (ET), SA and jasmonic acid (JA) pathways. This study should contribute to our understanding on the evolution and function of the SsTGA gene family in Saccharum, and provide a basis for the functional identification of ScTGA1 under biotic stresses.

Energy, economic, and environmental assessment of coriander seed production using material flow cost accounting and life cycle assessment

The agricultural sector in the world is facing social expectations to improve energy efficiency and reduce environmental impacts, and at the same producing enough food and fiber for the growing world population. The purpose of the present research is to determine the economic, energy consumption, and environmental impacts in coriander seed production using material flow cost accounting approach along with life cycle assessment. The positive output and negative energy were 25,485 and 6742 MJ ha-1, respectively. Energy efficiency, net energy gain, specific energy, and energy productivity indicators were calculated as 0.6, - 11,944 MJ ha-1, 17.4 MJ kg-1, and 0.06 kg MJ-1, respectively. The average production cost was calculated as 588 $ ha-1 whereas gross income was 1267 $ ha-1. The value of negative products in coriander production was estimated as 239 $ ha-1. Seed shedding at harvest and water loss due to inefficient irrigation system were found to be the major negative products (economic and energy) in the system that can enhance the system productivity upon improvement. The values of benefit costs ratio and economic productivity were 1.74 and 3 kg $-1, respectively. The acidification potential (102.5 kg SO2 eq ha-1), global warming potential (897.3 kg CO2 eq ha-1), photochemical oxidation potential (0.13 kg C2H4 eq ha-1), and eutrophication potential (40.3 kg PO4-3 eq ha-1) indicators were evaluated. The hotspots in point of economic (labor and seed shedding), energy use (nitrogen fertilizer and machinery) and energy loss (seed shedding), and environment (diesel fuel consumption) were determined which can be used to optimize coriander production through decreasing the material and energy consumption in the field. The results showed that MFCA combined with LCA is a powerful tool in identifying hotspots in crop production systems and can be used in developing more sustainable systems as well as in developing sustainability models.

Carbon footprint analysis of straw collection, transportation, and storage system for power generation in China based on emergy evaluation

Carbon footprint analysis method was employed to evaluate the ecological benefits of the straw collection, transportation, and storage system based on the case of Laifa Straw Recycling Company, and the emergy-based carbon emission indicator system was also set up to assess the relationship between input resource and carbon emission. In the condition of collecting 2 × 10⁸ kg of straw production, the carbon emission of the artificial model (7.26 × 10³ t CO_2eq) and mechanical model (6.11 × 10³ t CO_2eq) was greatly lower than that of the straw burned in the field (2.78 × 10⁵ t CO_2eq). According to the emergy-based carbon emission indicator system, the carbon emission of straw recycling system was mainly triggered from labor input, which could be reduced by adjusting the resource structure. The ratio of carbon emission to environmental loading rate (ELR_CO2) and ratio of carbon emission to emergy sustainability index (ESI_CO2) of the artificial model were 90.75E+6 kgCO_2eq and 1.52E+6 kgCO_2eq, respectively, which were higher than that of the mechanical model, 55.55E+6 kgCO_2eq and 1.22E+6 kgCO_2eq. It was obviously that the mechanical model had weaker influence on environmental loading than that of the artificial model and presented promising sustainable development ability in the case of mitigating carbon emissions.

The Environmental Profile of Ethanol Derived from Sugarcane in Ecuador: A Life Cycle Assessment Including the Effect of Cogeneration of Electricity in a Sugar Industrial Complex

The present study compiles a life cycle inventory for Ecuadorian sugarcane-derived ethanol production to quantify its environmental performance and identify the life cycle stages that cause major impacts. The scope of this study encompasses a cradle-to-gate analysis that includes the agriculture, the milling, the distillation, and the co-generation of electricity. This assessment is modeled using the OpenLCA v1.10.3 software. Two functional units (FU) were established in this study: “1 ton of sugarcane at-the-farm-gate” for the agricultural stage and “1 L of ethanol at-the-plant-gate”. A hybrid attributional and consequential life cycle analysis (LCA) approach has been followed. Economic allocation (EA) and system expansion (SE) were used to take co-products into account in the milling and co-generation of electricity stages, respectively. The co-generation stage is analyzed in three different scenarios: (i) average mix displacement scenario where the surplus electricity produced in the co-generation stage is displaced; (ii) marginal technology displacement scenario where the marginal surplus electricity is displaced from the mix and (iii) no displacement scenario. The global warming potential (GWP) impact at the farm gate level was reported as 53.6 kg of carbon dioxide equivalent (kg CO2eq.) per ton of sugarcane produced. The two main contributors of the agricultural stage correspond to N2O lixiviation and volatilization with 34% followed by the diesel used in agricultural machinery with 24%. The GWP for 1 L of ethanol produced was reported as 0.60 kg CO2eq. based on the average mix displacement scenario. No displacement scenario has a GWP impact of 0.84 kg CO2/liter of ethanol The distillation stage has the highest contribution to GWP impact with approximately 61% followed by the agricultural stage with 47%. The co-generation stage reports a contribution of −8.4% due to the surplus electricity displacement. The scenarios where the system expansion method is applied have a lower GWP impact compared to the scenario where no surplus electricity is displaced. Regarding terrestrial acidification potential impact, 0.01528 kg of SO2eq. was reported at the ethanol production level especially due to the nitrogen and phosphorous content in the vinasse produced from the distillation process. The marine eutrophication impact for 1 L of ethanol produced was 0.00381 kg of Neq. due to the content of nitrogen contained in the vinasse and the use of nitrogenous fertilizers in the agricultural stage. Finally, to create more eco-friendly Ecuadorian sugarcane and ethanol industries, sustainable and less polluting processes should be sought to reduce the environmental burdens. Companies should apply industrial symbiosis and circular economy strategies to produce lesser environmental loads within the ethanol production chain. The sugarcane industrial sector should also promote the surplus electricity production in order to gain credits.

Energetic and Economic Analysis of Spineless Cactus Biomass Production in the Brazilian Semi-arid Region

The Brazilian semi-arid region is marked by a variable spatial-temporal rainfall distribution, concentrated over a 3 to 4 month season. Limited water availability is the main obstacle to the production of forage plants of C3 metabolism (such as corn and soybeans) and C4 metabolism (such as sugarcane), as well as livestock. To mitigate this forage supply, the spineless cactus (SC) has been cultivated in the region, producing high biomass amounts in this harsh environment. Recently, this remarkable capacity to produce biomass has drawn the attention of the renewable energy sector, supported by recent studies demonstrating the feasibility of its biomass as a raw material for bioenergy production. However, before moving to commercial scale, it is necessary to demonstrate that large-scale production has energy and economic viability for clean energy investors. Thus, the objective of this article was to analyze the energetic and economic viability of forage cactus cultivation systems in the Brazilian semi-arid region. The data used were extracted from the literature, based on forage production. For the energy evaluation, the energy balance was performed and the energy efficiency, energy productivity, specific energy, and net energy metrics were applied. The financial feasibility analysis used the Net Present Value (NPV) and Internal Rate of Return (IRR). The energy balance revealed that the SC cultivation is viable for biomass commercial-scale production, with an energy efficiency of 3.36, an energy productivity of 0.25 kg MJ−1, a specific energy of 13.5 MJ kg−1, and an energy balance of 127,348 MJ ha−1. For the economic aspect, considering an attractive minimum rate of return of 8%, production also proved to be viable, in a time horizon of three years. The Net Present Value and IRR metrics were USD 2196 and the IRR was 46%, respectively. The results found are important to encourage new investments in rural properties in the semi-arid region, and cultivation in new areas proved to be an efficient alternative from an energy and economic point of view, in addition to collaborating for the energy transition to sustainable sources and in the mitigation of regional environmental impacts.

Pilot-scale co-processing of lignocellulosic biomass, algae, shellfish waste via thermochemical approach: Recent progress and future directions

Thermal co-processing of lignocellulosic and aquatic biomass, such as algae and shellfish waste, has shown synergistic effects in producing value-added energy products with higher process efficiency than the traditional method, highlighting the importance of scaling up to pilot-scale operations. This article discusses the design and operation of pilot-scale reactors for torrefaction, pyrolysis, and gasification, as well as the key parameters of co-processing biomass into targeted and improved quality products for use as fuel, agricultural application, and environmental remediation. Techno-economic analysis reveals that end product selling price, market dynamics, government policies, and biomass cost are crucial factors influencing the sustainability of thermal co-processing as a feasible approach to utilize the biomass. Because of its simplicity, pyrolysis allows greater energy recovery, while gasification has the highest net present value (profitability). Integration of liquefaction, hydrothermal, and fermentation pre-treatment technology has the potential to increase energy efficiency while reducing process residues.

Life cycle water footprint assessment of syngas production from biomass chemical looping gasification

Water is crucial for biofuel production. It is important to study the influence of biofuel technology on water resource for the development of biofuel. Life cycle water footprint for the syngas production via chemical looping gasification of corn straw and wheat straw is developed in this paper. The results show that the total water consumption of syngas production via corn straw and wheat straw chemical looping gasification are 1139.84 and 2170.41 L H₂O/m³ syngas, respectively. The total water consumption of the aforementioned approaches is both dominated by crop growth stage. Additionally, different allocation methods have significant impact on the total water consumption. Sensitivity analysis demonstrates that water consumption of crop yield and crop growth can have an almost same but opposite impact on water consumption efficiency. Based on the results, guidance can be provided for crop straw to syngas via chemical looping gasification to lower water use.