• Energy Research

A mathematical model to predict the influence of system parameters such as substrate concentrations and operation cycle time on MES performance.

This work presents new data on the life cycle impact assessment of various lignocellulosic biomass types in Mexico. A comparative life cycle assessment model of biomass densification systems was conducted. An integrated approach that incorporated various process variables, such as technology and variations in feed properties, within the analysis was employed to evaluate the environmental impact of producing 1 MJ of energy-containing densified fuel. The results show that the densification unit and curing (fuel drying) have the highest impact on the life cycle’s operational energy and the total life cycle energy, respectively. Of all the 33 biomass types from the 17 species sources considered in this study, sweet sorghum and sandbur grass have the highest global warming potential, 0.26 and 0.24 (kg CO2-eq), and human toxicity 0.58 and 0.53 (kg 1,4-dichlorobenzene-eq), respectively, while coffee pulp and cooperi pine wood have the least impact in both categories, with values of 0.08 and 0.09 (kg CO2-eq), and 0.17 and 0.16 (kg 1,4-dichlorobenzene-eq), respectively. Chichicaxtla sawmill slabs also have a low environmental impact, and cooperi pine and Ceiba wood have the lowest ozone depletion and ecotoxicity potential. A sensitivity analysis indicated the effects of the transportation system and energy source on the life cycle’s environmental impact. Adequate feed preparation, the blending of multiple feeds in the optimum ratio, and the careful selection of densification technology could improve the environmental performance of densifying some of the low-bulk-density feed biomass types.

Le pain est la deuxième denrée alimentaire la plus gaspillée au Royaume-Uni avec un gaspillage annuel de 292 000 tonnes. Dans le présent travail, les déchets de pain (BW) ont été utilisés pour la production fermentative d'éthanol par Saccharomyces cerevisiae KL17. La saccharification acide et enzymatique du BW a été réalisée, entraînant la libération de glucose la plus élevée de 75 et 97,9 g/L, soit 73,5 et 95,9% du rendement théorique, respectivement. Les sucres obtenus ont d'abord été fermentés en éthanol dans un ballon à secousses, puis mis à l'échelle dans un bioréacteur en mode batch et fed-batch. Dans le mode de culture fed-batch, les titres maximums en éthanol de 111,3, 106,9 et 114,9 g/L avec un rendement de conversion et une productivité de 0,48, 0,47 et 0,49 g/g et 3,1, 3,0 et 3,2 g/L.h ont été atteints à partir de glucose pur, d'hydrolysats acides riches en glucose et d'hydrolysats enzymatiques, respectivement. Pour améliorer davantage l'économie du processus, les résidus solides après hydrolyse acide (ABW) et enzymatique (EBW) de BW ainsi que les résidus de fermentation respectifs (FR) obtenus après la production d'éthanol ont été regroupés et soumis à une digestion anaérobie. Le résidu solide de ABW + FR et EBW + FR a donné un potentiel de méthanation biochimique (BMP) de 345 et 379 mL CH4/g VS, respectivement. L'évaluation du cycle de vie du processus a montré que les émissions totales pour la production d'éthanol à partir de BW étaient comparables aux émissions provenant de matières premières plus établies telles que la canne à sucre et les céréales de maïs et beaucoup plus faibles par rapport au blé et à la patate douce. Les travaux actuels démontrent que BW est une matière première prometteuse pour la production durable de biocarburants à l'aide d'une stratégie de bioraffinage circulaire. À la connaissance des auteurs, c'est la première fois qu'un tel système séquentiel a été étudié avec BW pour la production d'éthanol et de biométhane. D'autres travaux viseront la production d'éthanol à l'échelle pilote et le BMP sera accessible dans un digesteur anaérobie commercial. El pan es el segundo alimento más desperdiciado en el Reino Unido con un desperdicio anual de 292.000 toneladas. En el presente trabajo, Saccharomyces cerevisiae KL17 utilizó residuos de pan (BW) para la producción fermentativa de etanol. La sacarificación ácida y enzimática de BW se llevó a cabo dando como resultado la mayor liberación de glucosa de 75 y 97.9 g/L, que es 73.5 y 95.9% del rendimiento teórico, respectivamente. Los azúcares obtenidos se fermentaron en etanol inicialmente en un matraz de agitación, seguido de un aumento de escala en el biorreactor en modo por lotes y por lotes alimentados. En el modo de cultivo por lotes alimentados, las titulaciones máximas de etanol de 111.3, 106.9 y 114.9 g/L con rendimiento de conversión y productividad de 0.48, 0.47 y 0.49 g/g, y 3.1, 3.0 y 3.2 g/L.h se lograron a partir de glucosa pura, hidrolizados ácidos y enzimáticos ricos en glucosa, respectivamente. Además, para mejorar la economía del proceso, los residuos sólidos después de la hidrólisis ácida (ABW) y enzimática (EBW) de BW junto con los respectivos residuos de fermentación (FR) obtenidos después de la producción de etanol se agruparon y se sometieron a digestión anaeróbica. El residuo sólido de ABW + FR y EBW + FR produjo un potencial de metanización bioquímica (BMP) de 345 y 379 mL CH4/g VS, respectivamente. La evaluación del ciclo de vida del proceso mostró que las emisiones totales para la producción de etanol de BW eran comparables a las emisiones de materias primas más establecidas como la caña de azúcar y el grano de maíz y mucho menores en comparación con el trigo y la batata. El trabajo actual demuestra que el BW es una materia prima prometedora para la producción sostenible de biocombustibles con la ayuda de una estrategia circular de biorrefinado. Hasta donde saben los autores, esta es la primera vez que se ha investigado un sistema secuencial de este tipo con BW para la producción de etanol y biometano. Se trabajará más en la producción de etanol a escala piloto y se accederá a BMP en un digestor anaeróbico comercial. Bread is the second most wasted food in the UK with annual wastage of 292,000 tons. In the present work, bread waste (BW) was utilized for fermentative production of ethanol by Saccharomyces cerevisiae KL17. Acidic and enzymatic saccharification of BW was carried out resulting in the highest glucose release of 75 and 97.9 g/L which is 73.5 and 95.9% of theoretical yield, respectively. The obtained sugars were fermented into ethanol initially in shake flask followed by scale up in bioreactor in batch and fed-batch mode. In the fed-batch mode of cultivation, the maximum ethanol titers of 111.3, 106.9, and 114.9 g/L with conversion yield and productivity of 0.48, 0.47, and 0.49 g/g, and 3.1, 3.0, and 3.2 g/L.h was achieved from pure glucose, glucose-rich acidic and enzymatic hydrolysates, respectively. Further to improve the process economics, the solid residues after acidic (ABW) and enzymatic (EBW) hydrolysis of BW along with respective fermentation residues (FR) obtained after the ethanol production were pooled and subjected to anaerobic digestion. The solid residue from ABW + FR, and EBW + FR yielded a biochemical methanation potential (BMP) of 345 and 379 mL CH4/g VS, respectively. Life cycle assessment of the process showed that the total emissions for ethanol production from BW were comparable to the emissions from more established feedstocks such as sugarcane and maize grain and much lower when compared to wheat and sweet potato. The current work demonstrates BW as promising feedstock for sustainable biofuel production with the aid of circular biorefining strategy. To the authors knowledge, this is the first time, such a sequential system has been investigated with BW for ethanol and biomethane production. Further work will be aimed at ethanol production at pilot scale and BMP will be accessed in a commercial anaerobic digester. الخبز هو ثاني أكثر المواد الغذائية المهدرة في المملكة المتحدة مع هدر سنوي يبلغ 292000 طن. في العمل الحالي، تم استخدام نفايات الخبز (BW) للإنتاج التخميري للإيثانول بواسطة Sacaromyces cerevisiae KL17. تم إجراء التسكير الحمضي والإنزيمي للأسلحة البيولوجية مما أدى إلى أعلى إطلاق للجلوكوز يبلغ 75 و 97.9 جم/لتر وهو 73.5 و 95.9 ٪ من العائد النظري، على التوالي. تم تخمير السكريات التي تم الحصول عليها في الإيثانول في البداية في قارورة مخفوقة تليها زيادة في المفاعل الحيوي في وضع الدفعة والدفعة المغذية. في وضع الدفعات الغذائية للزراعة، تم تحقيق الحد الأقصى من تيترات الإيثانول 111.3 و 106.9 و 114.9 جم/لتر مع عائد تحويل وإنتاجية 0.48 و 0.47 و 0.49 جم/جم و 3.1 و 3.0 و 3.2 جم/لتر من الجلوكوز النقي والحمض الغني بالجلوكوز والحموض الأنزيمية، على التوالي. ولتحسين اقتصاديات العملية، تم تجميع المخلفات الصلبة بعد التحلل المائي الحمضي والإنزيمي للأسلحة البيولوجية جنبًا إلى جنب مع مخلفات التخمير ذات الصلة التي تم الحصول عليها بعد إنتاج الإيثانول وإخضاعها للهضم اللاهوائي. أسفرت المخلفات الصلبة من القنابل المضادة للدبابات + القنابل المقاومة للحريق، والقنابل المضادة للدبابات + القنابل المقاومة للحريق عن جهد ميثان كيميائي حيوي (BMP) قدره 345 و 379 مل من الميثان/جم مقابل، على التوالي. أظهر تقييم دورة حياة العملية أن إجمالي الانبعاثات لإنتاج الإيثانول من الأسلحة البيولوجية كانت قابلة للمقارنة مع الانبعاثات من المواد الأولية الأكثر رسوخًا مثل قصب السكر وحبوب الذرة وأقل بكثير بالمقارنة مع القمح والبطاطا الحلوة. يوضح العمل الحالي أن الأسلحة البيولوجية هي مادة وسيطة واعدة لإنتاج الوقود الحيوي المستدام بمساعدة استراتيجية التكرير الحيوي الدائرية. على حد علم المؤلفين، هذه هي المرة الأولى، وقد تم التحقيق في مثل هذا النظام المتسلسل مع الأسلحة البيولوجية لإنتاج الإيثانول والميثان الحيوي. سيهدف المزيد من العمل إلى إنتاج الإيثانول على نطاق تجريبي وسيتم الوصول إلى BMP في جهاز هضم لاهوائي تجاري.

A novel framework, integrating dynamic simulation (DS), life cycle assessment (LCA) and techno-economic assessment (TEA) of a bioelectrochemical system (BES), has been developed to study for the first time wastewater treatment by removal of chemical oxygen demand (COD) by oxidation in anode and thereby harvesting electron and proton for carbon dioxide reduction reaction or reuse to produce products in cathode. Increases in initial COD and applied potential increase COD removal and production (in this case formic acid) rates. DS correlations are used in LCA and TEA for holistic performance analyses. The cost of production of HCOOH is €0.015-0.005 g-1 for its production rate of 0.094-0.26 kg yr-1 and a COD removal rate of 0.038-0.106 kg yr-1. The life cycle (LC) benefits by avoiding fossil-based formic acid production (93%) and electricity for wastewater treatment (12%) outweigh LC costs of operation and assemblage of BES (-5%), giving a net 61MJkg-1 HCOOH saving.

A novel and fast-converging cost minimization model using non-linear constrained mathematical programming (NLP) has been developed to optimize renewable and bioenergy generation and storage systems’ capacities for transitioning to an electricity system with net-zero greenhouse gas emissions. Running this temporal and spatial multi-scale model gives an in-depth understanding of realistic electricity mixes in sustainable transitioning. The model comprises three interactive modules 1) analytics and visualization of data inputs, climatic and demand time-series, and design configurations, and output results, optimal electricity mix, and storage characteristics, 2) mathematical models of renewable generation systems using non-linear climate-dependent capacity factor time-series and energy system components, and 3) NLP to minimize the total cost. Hourly and total energy balances are the crucial constraints influencing the speed and efficacy of the solution. Fast-converged solutions of the NLP model are updated considering battery energy storage with a few hours dispatch time for attainable optimum net-zero electricity (NZE) mix. The NLP optimization model is tested on the energy-intensive UK South. The feasible optimum regional solutions characterized as high renewable supply-medium-to-high-demand (South West), low-supply-medium-demand (Greater London), and high-supply-high-demand (South East) scenarios are projected to the UK national level. The inputs to the NLP model are wind speed and solar radiation with annual hourly resolutions curated from the Centre for Environmental Data Analysis, process economic parameters (investment, fixed, operating, and resource costs, weighted average cost of capital, and life in years of processes) from the LUT energy system model, and global warming potential impacts from our archived literature. 2020-2050 electricity mixes are analyzed with varying costs and demands. The NLP optimization followed by energy storage feasibility analysis gives the following attainable optimal energy mixes: wind: 55%, solar: 29%, hydro: 0.5%, geothermal: 0.4%, and bioenergy: 1% (high-supply-medium-to-high-demand); wind: 52%, solar: 32%, hydro: 0.5%, geothermal: 0.5%, and bioenergy: 1% (low-supply-medium-demand); and wind: 45%, solar: 23%, hydro: 0.7%, geothermal: 0.7%, and bioenergy: 10% (high-supply-high-demand). Energy storage (13.5 TWh in the UK South) with 13-22% contributions of load demand (80 TWh in the UK South) costs 14% of the levelized cost of electricity production, 120-190 EURO/MWh. The high-supply-medium-to-high-demand scenario, providing the UK NZE projection of wind: 40GW, solar: 21GW, bioenergy and other renewables: 5GW, nuclear: 6GW, and gas with carbon capture, utilization, storage, and sequestration (CCUS): 5GW by 2050, mirrors the government's NZE plan. The additional wind (currently at 8.65GW), solar (currently at 1.5GW), and CCUS (currently there is none) capacities require £23 billion, £4 billion, and £1 billion investment costs.

According to the US Department of Energy, succinic acid (SA) is a top platform chemical that can be produced from biomass. Bread waste, which has high starch content, is the second most wasted food in the UK and can serve as a potential low cost feedstock for the production of SA. This work evaluates the environmental performance of a proposed biorefinery concept for SA production by fermentation of waste bread using a cradle-to-factory gate life cycle assessment approach. The performance was assessed in terms of greenhouse gas (GHG) emissions and non-renewable energy use (NREU). Waste bread fermentation demonstrated a better environmental profile compared to the fossil-based system, however, GHG emissions were about 50% higher as compared to processes using other biomass feedstocks such as corn wet mill or sorghum grains. NREU for fermentative SA production using waste bread was significantly lower (~ 46%) than fossil-based system and about the same as that of established biomass-based processes, thus proving the great potential of waste bread as a valuable feedstock for bioproduction of useful chemicals. The results show that steam and heating oil used in the process were the biggest contributors to the NREU and GHG emissions. Sensitivity analyses highlighted the importance of the solid biomass waste generated in the process which can potentially be used as fish feed. The LCA analysis can be used for targeted optimization of SA production from bread waste, thereby enabling the utilization of an otherwise waste stream and leading to the establishment of a circular economy.

Incorporating nanomaterials into Microbial Fuel Cells (MFCs) is gaining interest as a promising approach for sustainable energy production via microbial metabolism.