• Energy Research

Abstract Bio-based plastics are produced from bio-based raw materials such as sugar cane, potatoes, corn, and agricultural and slaughterhouse waste. The evolution of the bio-based plastics market is affected by the stakeholders involved owing to their role in production processes, environmental guidelines and purchasing decisions. It is therefore imperative to understand the perceptions of stakeholders in order to inform the development of the bio-based plastics sector. This novel exploratory study investigates the perceptions and opinions of three stakeholder groups: environmental professionals and plastic processors; university students; and consumers in Belfast, Northern Ireland. During the focus groups (25 participants in total), samples of bio-based plastics, including starch-based monolayer and multilayer, and polyethylene terephthalate (PET), were presented. A qualitative analysis using the framework method revealed that environmental professionals and plastic processors were aware of both the benefits of bio-based plastics, such as a reduction in use of fossil fuels; and the challenges, which include the utilisation of agricultural land for biomass substrates and possible contamination of current conventional plastic recycling streams. Although there was a general lack of knowledge among students and consumers about bio-based plastics, they conveyed their beliefs that the use of agricultural waste will lead to closed-loop systems, resulting in a balanced approach to production and waste management. Some students and consumers, raised concerns about contamination of food by bio-based packaging prepared from slaughterhouse waste. However, these participants supported the use of slaughterhouse waste in the production of bio-based plastics for non-food contact items. The students and consumers and some of the environmental professionals and plastic processors were reluctant to pay more for bio-based plastics. The results indicate that manufacturers of bio-based plastics could benefit from informing consumers about the environmental impacts of beginning-of-life parameters, such as production processes and feedstocks, by using life cycle assessment parameters. This should be incorporated into information provided on labelling using standards from neutral organisations. This research could inform future communication strategies around bio-based plastics with both the public and industry.

AbstractClimate change issues are calling for advanced methods to produce materials and fuels in a carbon–neutral and circular way. For instance, biomass pyrolysis has been intensely investigated during the last years. Here we review the pyrolysis of algal and lignocellulosic biomass with focus on pyrolysis products and mechanisms, oil upgrading, combining pyrolysis and anaerobic digestion, economy, and life cycle assessment. Products include oil, gas, and biochar. Upgrading techniques comprise hot vapor filtration, solvent addition, emulsification, esterification and transesterification, hydrotreatment, steam reforming, and the use of supercritical fluids. We examined the economic viability in terms of profitability, internal rate of return, return on investment, carbon removal service, product pricing, and net present value. We also reviewed 20 recent studies of life cycle assessment. We found that the pyrolysis method highly influenced product yield, ranging from 9.07 to 40.59% for oil, from 10.1 to 41.25% for biochar, and from 11.93 to 28.16% for syngas. Feedstock type, pyrolytic temperature, heating rate, and reaction retention time were the main factors controlling the distribution of pyrolysis products. Pyrolysis mechanisms include bond breaking, cracking, polymerization and re-polymerization, and fragmentation. Biochar from residual forestry could sequester 2.74 tons of carbon dioxide equivalent per ton biochar when applied to the soil and has thus the potential to remove 0.2–2.75 gigatons of atmospheric carbon dioxide annually. The generation of biochar and bio-oil from the pyrolysis process is estimated to be economically feasible.

Abstract The use of renewable resources is becoming increasingly important if we are to address the negative impacts of petroleum-based polymers. Utilising renewable resources, such as agri-food wastes (AFWs), for biopolymer production offers the advantages of lower dependence on fossil fuels, resource recovery (generating added value), and waste management. AFWs are generated as by-products or residues at every stage of the food supply chain: harvest, processing, and post-consumption. AFWs are a significant societal challenge but their full potential as renewable resources remain unexploited. Hence, this study aimed to identify feedstocks that can provide a continuous supply of raw materials for the manufacture of biopolymers. Harvest and process wastes from major crops were assessed using information from published reports and government departments over the period 2013‐2017. The analysis was based on criteria focusing on the availability, characteristics, and market value of the identified AFWs. The analysis was conducted for the crops: wheat, barley, oats, rapeseed, sugar beet, carrots, and onions. Total AFW production in the UK over the reference period was estimated at 15 Mt dry matter/yr, to which wheat is the major contributor (≈7 Mt). The results show that harvest residues, e.g., straw, have medium to high theoretical availability and competing uses, whereas processing residues, e.g., onion peels, have low theoretical availability and cost but are well suited for biopolymer production. These findings provide valuable information about resources that will enable potential investors to conduct studies to accurately assess the practicality of valorising AFWs into biopolymers.

Supply of resources, a growing population, and environmental pollution are some of the main challenges facing the contemporary world. The rapid development of mining activities has produced huge amounts of waste. This waste, found in abandoned mine sites, provides the potential opportunity of extracting raw material. The current study, therefore, focuses on testing the validation of a shared methodology to recover extractive waste from abandoned mines, and applies this methodology to a case study in Gorno, northwest Italy. The methods focused on: (1) analyzing the impact of tailings and fine fraction of waste rock (<2 mm) on plants (Cress - Lepidium Sativum) to assess usability of both as soil additive, and (2) recovering raw materials from tailings and coarse fraction (>2 mm) of waste rock, by means of dressing methods like wet shaking table and froth flotation. The results indicated that the fine fraction of waste rock and tailings did not have detrimental effects on seed germination; however, there was marked decrease in plant growth. As for the recovery of raw materials, the coarse waste rock samples, crushed to <0.5 mm, produced a recovery of Cd, Ga, and Zn—as much as 66%, 56%, and 64%, respectively—using the wet shaking table. The same samples when crushed to 0.063–0.16 mm and used for froth flotation produced a recovery of Cd, Ga, and Zn of up to 61%, 72%, and 47%, respectively. The flotation experiment on tailings showed a recovery of Cd, Ga and Zn at pH 7 of 33%, 6% and 29% respectively. The present investigation highlights the methodologies used for extracting raw materials from extractive waste.

AbstractThe global energy demand is projected to rise by almost 28% by 2040 compared to current levels. Biomass is a promising energy source for producing either solid or liquid fuels. Biofuels are alternatives to fossil fuels to reduce anthropogenic greenhouse gas emissions. Nonetheless, policy decisions for biofuels should be based on evidence that biofuels are produced in a sustainable manner. To this end, life cycle assessment (LCA) provides information on environmental impacts associated with biofuel production chains. Here, we review advances in biomass conversion to biofuels and their environmental impact by life cycle assessment. Processes are gasification, combustion, pyrolysis, enzymatic hydrolysis routes and fermentation. Thermochemical processes are classified into low temperature, below 300 °C, and high temperature, higher than 300 °C, i.e. gasification, combustion and pyrolysis. Pyrolysis is promising because it operates at a relatively lower temperature of up to 500 °C, compared to gasification, which operates at 800–1300 °C. We focus on 1) the drawbacks and advantages of the thermochemical and biochemical conversion routes of biomass into various fuels and the possibility of integrating these routes for better process efficiency; 2) methodological approaches and key findings from 40 LCA studies on biomass to biofuel conversion pathways published from 2019 to 2021; and 3) bibliometric trends and knowledge gaps in biomass conversion into biofuels using thermochemical and biochemical routes. The integration of hydrothermal and biochemical routes is promising for the circular economy.

Les déchets de plastique et de biomasse posent un risque grave pour l'environnement ; ainsi, ici, nous avons mélangé des déchets de biomasse avec des déchets de bouteilles en plastique (PET) pour produire des matériaux composites de charbon pour produire un composite de charbon magnétique pour une meilleure séparation lorsqu'il est utilisé dans des applications de traitement de l'eau. Cette étude a également calculé les impacts environnementaux du cycle de vie de la préparation du matériau adsorbant pour 11 catégories d'indicateurs différentes. Pour 1 unité fonctionnelle (1 kg de feuilles de marc comme matière première), l'épuisement abiotique des combustibles fossiles et le potentiel de réchauffement climatique ont été quantifiés à 7,17 MJ et 0,63 kg d'équivalent CO2 pour la production de matériaux composites à base de charbon magnétique. Le matériau composite de carbonisation magnétique (MPBC) a ensuite été utilisé pour éliminer le colorant violet cristallin de sa solution aqueuse selon divers paramètres opérationnels. Les théories statistiques de la cinétique et de l'isotherme ont montré que la sorption du colorant CV sur le MPBC était régie par des modèles de pseudo-seconde-ordre et de Langmuir, respectivement. L'évaluation quantitative de la capacité de sorption clarifie que le MPBC produit présentait une capacité admirable de 256,41 mg g-1. Pendant ce temps, la recyclabilité de 92,4 % de MPBC a été démontrée après 5 cycles d'adsorption/désorption. Les résultats de cette étude inspireront une production plus durable et plus rentable de sorbants magnétiques, y compris ceux dérivés de flux de déchets de plastique et de biomasse combinés. Los residuos plásticos y de biomasa representan un grave riesgo ambiental; por lo tanto, en este documento, mezclamos residuos de biomasa con residuos de botellas de plástico (PET) para producir materiales compuestos de carbón para producir un compuesto de carbón magnético para una mejor separación cuando se usa en aplicaciones de tratamiento de agua. Este estudio también calculó los impactos ambientales del ciclo de vida de la preparación de material adsorbente para 11 categorías de indicadores diferentes. Para 1 unidad funcional (1 kg de hojas de orujo como materia prima), el agotamiento abiótico de los combustibles fósiles y el potencial de calentamiento global se cuantificaron como 7,17 MJ y 0,63 kg de CO2 equivalente para la producción de materiales compuestos de carbón magnético. El material compuesto de carbón magnético (MPBC) se utilizó luego para eliminar el colorante violeta cristal de su solución acuosa bajo varios parámetros operativos. Las teorías estadísticas de cinética e isoterma mostraron que la sorción del colorante CV en MPBC estaba gobernada por modelos de pseudo-segundo orden y Langmuir, respectivamente. La evaluación cuantitativa de la capacidad de sorción aclara que el MPBC producido exhibió una capacidad admirable de 256.41 mg g-1. Mientras tanto, la reciclabilidad del 92.4% de MPBC se demostró después de 5 ciclos de adsorción/desorción. Los resultados de este estudio inspirarán una producción más sostenible y rentable de sorbentes magnéticos, incluidos los derivados de flujos combinados de residuos plásticos y de biomasa. Plastic and biomass waste pose a serious environmental risk; thus, herein, we mixed biomass waste with plastic bottle waste (PET) to produce char composite materials for producing a magnetic char composite for better separation when used in water treatment applications. This study also calculated the life cycle environmental impacts of the preparation of adsorbent material for 11 different indicator categories. For 1 functional unit (1 kg of pomace leaves as feedstock), abiotic depletion of fossil fuels and global warming potential were quantified as 7.17 MJ and 0.63 kg CO2 equiv for production of magnetic char composite materials. The magnetic char composite material (MPBC) was then used to remove crystal violet dye from its aqueous solution under various operational parameters. The kinetics and isotherm statistical theories showed that the sorption of CV dye onto MPBC was governed by pseudo-second-order, and Langmuir models, respectively. The quantitative assessment of sorption capacity clarifies that the produced MPBC exhibited an admirable ability of 256.41 mg g-1. Meanwhile, the recyclability of 92.4% of MPBC was demonstrated after 5 adsorption/desorption cycles. Findings from this study will inspire more sustainable and cost-effective production of magnetic sorbents, including those derived from combined plastic and biomass waste streams. تشكل نفايات البلاستيك والكتلة الحيوية خطرًا بيئيًا خطيرًا ؛ وبالتالي، هنا، قمنا بخلط نفايات الكتلة الحيوية مع نفايات الزجاجات البلاستيكية (PET) لإنتاج مواد مركبة من الفحم لإنتاج مركب فحم مغناطيسي لفصل أفضل عند استخدامه في تطبيقات معالجة المياه. كما حسبت هذه الدراسة التأثيرات البيئية لدورة الحياة لإعداد المواد الممتزة لـ 11 فئة مختلفة من المؤشرات. بالنسبة لوحدة وظيفية واحدة (1 كجم من أوراق الثفل كمادة وسيطة)، تم تحديد النضوب اللاأحيائي للوقود الأحفوري وإمكانات الاحترار العالمي على أنها 7.17 ميجا جول و 0.63 كجم من مكافئ ثاني أكسيد الكربون لإنتاج المواد المركبة للفحم المغناطيسي. ثم تم استخدام المادة المركبة للفحم المغناطيسي (MPBC) لإزالة الصبغة البنفسجية البلورية من محلولها المائي تحت معايير تشغيلية مختلفة. أظهرت النظريات الإحصائية للحركية والحرارة المتساوية أن امتصاص صبغة CV على MPBC كان محكومًا بنماذج زائفة من الدرجة الثانية، ونماذج Langmuir، على التوالي. يوضح التقييم الكمي لقدرة الامتصاص أن خلايا الدم البيضاء المنتجة أظهرت قدرة مثيرة للإعجاب تبلغ 256.41 ملغ غرام -1. وفي الوقت نفسه، تم إثبات قابلية إعادة تدوير 92.4 ٪ من حاوية الحاويات متعددة الأغراض بعد 5 دورات من الامتزاز/الامتزاز. ستلهم نتائج هذه الدراسة إنتاجًا أكثر استدامة وفعالية من حيث التكلفة للمواد الماصة المغناطيسية، بما في ذلك تلك المستمدة من تدفقات نفايات البلاستيك والكتلة الحيوية مجتمعة.

The need to mitigate climate change and improve energy security has led to an increasing interest in the utilisation of renewable gas to decarbonise natural gas use. Northern Ireland serves as an interesting case study to evaluate how biomethane from manure and silage material can displace natural gas. This is because of high agricultural intensity, the low penetration of gas relative to the wider UK and the modern pipeline infrastructure. This study included spatial mapping of biomethane yield and life cycle assessment for processing scenarios. The results demonstrated that current manure management i.e., storage and application of manure to grassland, results in 344 kg CO2 equivalent/person of greenhouse gases and 9.7 kg/person of ammonia being emitted. In a second scenario where collected manure and underutilised grass silage is routed to anaerobic digestion, the estimated net energy produced is 6124 GWh, with −464 kg CO2 equivalent/person. A third scenario, combining anaerobic digestion and pyrolysis, also produces 6124 GWh and 200 kilo tonnes of biochar (retaining 64% of manure phosphorus), −563 kg CO2 equivalent/person. This research evaluates the opportunity for biomethane while acknowledging that a comprehensive approach which balances energy potentials and nutrient management is required for sustainable biomethane based decarbonisation.