115 research outputs found
Influence of temperature and other system parameters on microbial fuel cell performance: numerical and experimental investigation
No full textThis study presents a steady state, two dimensional mathematical model of microbial fuel cells (MFCs) developed by coupling mass, charge and energy balance with the bioelectrochemical reactions. The model parameters are estimated and validated using experimental results obtained from five air-cathode MFCs operated at different temperatures. Model analysis correctly predicts the nonlinear performance trend of MFCs with temperatures ranging between 20 °C and 40 °C. The two dimensional distribution allows the computation of local current density and reaction rates in the biofilm, helping to correctly capture the interdependence of system variables and predict the drop in power density at higher temperatures. Model applicability for parametric analysis and process optimization is further highlighted by studying the effect of electrode spacing and ionic strength on MFC performance.</p
Dynamic feed scheduling for optimised anaerobic digestion: an optimisation approach for better decision-making to enhance revenue and environmental benefits
No full textAnaerobic digestion (AD) offers a sustainable solution for clean energy production, with the potential for significant revenue enhancement through enhanced decision-making. However, the complexity and limited flexibility of AD systems pose challenges in developing reliable optimisation methods. Changing feeding strategies provides opportunities for efficient feedstock utilisation and optimal gas production, especially in volatile gas markets.To provide better decision-making tools in AD for energy production, we propose an integrated site model for the dynamic behaviour of the AD process in a biomethane-to-grid system and optimise production based on predicted gas prices. The model includes methods for optimal feed co-digestion strategies and integrates these results into a scheduling model to identify the optimal feedstock acquisition, feeding pattern, and potential gas storage operation considering feedstock availability, properties, sustainability, and fluctuating gas demand under different pricing variations.The methodology was tested on a 150 tonnes per day farm-scale AD plant in the UK, processing energy crops and manure considering both environmental (global warming potential) and economic objectives. The results showed strong adaptability of the proposed feeding schedule to the general trend of gas prices over time. To address the challenge of immediate price peaks, typically unattainable due to the system's sluggish behaviour and high retention times, the impacts of on-site storage were explored, leading to annual revenue increases ranging from 2 % to 7.4 %, depending on the pricing scheme, which translates to a significant boost in terms of revenue
A multilevel sustainability analysis of zinc recovery from wastes
No full textAs waste generation increases with increasing population, regulations become stricter to control and mitigate environmental emissions of substances, e.g. heavy metals: zinc and copper. Recovering these resources from wastes is the key interest of industries. The objective of this paper is the sustainability and feasibility evaluations of zinc recovery from waste streams. Sustainability and feasibility of a resource recovery strategy from wastes in a circular economy are governed by avoided environmental impacts and cost-effective transformation of an environmental contaminant into a valuable resource, e.g. as a coproduct by making use of an existing infrastructure as much as possible. This study, for the first time, gives a comprehensive overview of secondary sources and processes of recovering zinc, its stock analysis by country, regional and global divisions by a Sankey diagram, policies to regulate zinc emissions and avoided environmental impacts by zinc recovery. Two representative cases are further investigated for economic feasibility analysis of zinc recovery from 1) steelmaking dust and (2) municipal solid waste (MSW). The amount and value of zinc that can be generated from dust emitted from various steelmaking technologies are estimated. Additional revenues for the steelmaking industrial sector (with electric arc furnace), at the plant, national (UK), regional (EU) and global levels are 11, 12, 169 and 1670 million tonne/y, or 19-143, 20-157, 287-2203 and 2834-21740 million €/y, respectively. The second case study entails an integrated mechanical biological treatment (MBT) system of MSW consisting of metal recovery technologies, anaerobic digestion, refuse derived fuel (RDF) incineration and combined heat and power (CHP) generation. An effective economic value analysis methodology has been adopted to analyse the techno-economic feasibility of the integrated MBT system. The value analysis shows that an additional economic margin of 500 € can be generated from the recovery of 1 tonne of zinc in the integrated MBT system enhancing its overall economic margin by 9%.Zinc, a very abundant heavy metal in waste streams, represents a hazardous heavy metal and a possible resource. The paper gives an overview of the secondary sources and presents an assessment of the feasibility of recovery of zinc from them.The authors would like to thank the UK Natural Environment Research Council (NERC) for supporting this project (NE/L014246/1 Resource Recovery from Wastewater with Bioelectrochemical Systems: http://gtr.rcuk.ac.uk/project/B45DB07A-A707-4005-A8ED-D1F564C28853)
A Critical Review of Integration Analysis of Microbial Electrosynthesis (MES) Systems with Waste Biorefineries for the Production of Biofuel and Chemical from Reuse of CO2
No full textDespite some success with microbial fuel cells and microbial electrolysis cells in recovering resources from wastes, challenges with their scale and yield need to be resolved. Waste streams from biorefineries e.g. bioethanol and biodiesel plants and wastewaters are plausible substrates for microbial electrosynthesis (MES). MES integration can help biorefineries achieving the full polygeneration potentials, i.e. recovery of metals turning apparently pollutants from biorefineries into resources, production of biofuels and chemicals from reuse of CO2 and clean water. Symbiotic integration between the two systems can attain an economic and environmental upside of the overall system. We envision that electrochemical technologies and waste biorefineries can be integrated for increased efficiency and competitiveness with stillage released from the latter process used in the former as feedstock and energy resource recovered from the former used in the latter. Such symbiotic integration can avoid loss of material and energy from waste streams, thereby increasing the overall efficiency, economics and environmental performance that would serve towards delivering the common goals from both the systems. We present an insightful overview of the sources of organic wastes from biorefineries for integration with MES, anodic and cathodic substrates and biocatalysts. In addition, a generic and effective reaction and thermodynamic modelling framework for the MES has been given for the first time. The model is able to predict multi-component physico-chemical behaviour, technical feasibility and best configuration and conditions of the MES for resource recovery from waste streams.</p
Life cycle, techno-economic and dynamic simulation assessment of bioelectrochemical systems: A case of formic acid synthesis
No full textA 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
What Is Environmental Biotechnology? Although Widely Applied, a Clear Definition of the Term Is Still Needed
No full textThe term Environmental Biotechnology is widely used, but lacks a universally accepted definition, with varying interpretations across disciplines and sectors leading to challenges in funding, policy formulation, and interdisciplinary collaboration. Through a literature review and engagement activities, this study examines existing definitions, identifies key areas of divergence, and explores pathways toward a more cohesive understanding. Findings reveal a spectrum of valid interpretations, often shaped by specific contexts, with researchers generally recognising a shared conceptual framework within their own subfields but encountering ambiguities across subject boundaries. Common points of difference include whether Environmental Biotechnology is restricted to microorganisms or encompasses other biological systems. Some understandings reflect sector-specific needs, contributing to fragmentation, though a broader approach could strengthen the field’s identity by providing a unifying framework, mapping overlaps with related fields such as Industrial Biotechnology. A working definition is proposed for Environmental Biotechnology as the use of biologically mediated systems for environmental protection and bioremediation, incorporating resource recovery and bioenergy production where these enhance system sustainability. Importantly, it was recognised that any definition must remain adaptable, reflecting the evolving nature of both the science and its applications
Enhanced air emission inventory for LCA of Kuwait Crude Oils
No full textLife cycle Assessments (LCAs) of crude oil derived products such as fuels, petrochemicals and polymers benefit from robust inventories of emissions and consumptions of the specific ways in which the crude oil can be extracted and processed. It is known that there is variation of up to 30% or more in the Greenhouse gas (GHG) ‘footprint’ of different crude oils depending upon the different crude types, production systems, geographic location etc. It is also known that in a number of comparative LCA analyses between petrochemical products and bio-based alternatives there can be rather small differences (e.g. 10 – 20%) in the GHG emissions or other environmental impacts. The large potential range in emissions profile per unit of crude oil and the sometimes-small margin of difference between crude-oil based products and alternatives suggests that the specific route of crude production (and processing) will be an important factor in decision-making and policy centred on environmental criteria. The research in this thesis was conducted to examine the site-specific air emission data, with emphasis on VOCs, for crude oil production and how this could affect the results of LCAs of petrochemical products in comparison with the use of generic LCA database data to characterize the environmental profiles of such products.
Company specific air emission data was collected from an upstream crude oil & gas company in Kuwait. The data collected was company available modelled data and new field measurements collected via the use of a mobile laboratory. This emission data was converted to specific substance emission values via Gaussian plume modelling and relating it to crude oil flows in the upstream facilities. Thereby new, specific LCI datasets for the air emissions of Kuwaiti crude oil were developed and deployed in LCAs to assess their effects on the environmental profiles of such crude oil and its end products. These LCAs demonstrated considerable heterogeneity in aspects of the environmental profile of the crude oils and example downstream end products driven by the specific LCI datasets for the various production systems examined
Sustainable Generation Expansion Planning with renewables: A case study of Bahrain
No full textBahrain was the first Gulf Cooperation Country (GCC) to discover oil. Since then, oil has become the keystone of the country's economic development, reflecting on all sectors, particularly power generation. This underlines the difficulty of shifting from well-established oil-based power production to renewable energy. Nevertheless, a significant milestone was achieved in January 2017, when the Sustainable Energy Unit (SEU) launched the National Renewable Energy Action Plan (NREAP). The plan sets the roadmap for identifying the most appropriate renewable resources for Bahrain and its best technologies. Special attention should be paid to Sustainable Generation Expansion Planning (GEP) for Bahrain's electrical system with renewables. This is because Bahrain's government is committed to the Sustainable Development Goals (SDG) and has incorporated them into its action plan since 2015.The sustainability theme in the energy system interacts with different research areas, and it requires a multidimensional approach to cover its impact on the national grid, environment, economy and other sectors. This study aims to assist Bahrain's policymakers in evaluating the renewable energy technologies for sustainable growth of the generation sector by suggesting an Intelligent Decision Support System (IDSS) based on a combination of the Analytical Hierarchy Process (AHP) and Artificial Neural Networks (ANN). After evaluating the derived indicators from seventy-three studies by experts and applying the selection principles, fifteen indicators are selected for constructing the AHP model. The AHP model outcomes revealed that wind turbines are the most appropriate technology for Bahrain. Then, the ANN model is structured based on the generated cases from the AHP model. The Levenberg–Marquardt algorithm is used for processing the data with a hyper tangent sigmoid and a linear function for the hidden layer and output layer of the ANN model. The scenario analysis demonstrates that the IDSS can be used with confidence to explore the effect of each criterion and sub-criterion on the sustainable growth of the electrical grid in Bahrain.</p
Novel life cycle GHG formulations of anaerobic digestion systems aligned with policy
No full textAmidst rising interest in biogas as a sustainable alternative to traditional energy vectors like natural gas, this study focuses on its role in achieving net-zero targets. Biogas, derived from carbon-neutral organic waste, offers significant greenhouse gas (GHG) emission reductions. Life cycle assessments (LCA) are crucial for evaluating the global warming potential (GWP) of biogas, ensuring its effectiveness in offsetting fossil fuel equivalents. Our study introduces two complementary sets of equations, grounded in published literature and LCA databases. Despite their differing structures due to distinctive specific activities across life cycles, both sets yield closely aligned estimations, reinforcing confidence in these models
Multiscale simulation for high efficiency biodiesel process intensification
No full textDesign of highly efficient multifunctional reaction processes for energy production is one of the main focus areas of Chemical Engineering. This article presents multiscale simulation frameworks for heterogeneously catalyzed reactors wherein numerous synthesis steps are integrated for high efficiency biodiesel production. The goal is the modeling of transport-adsorption-reaction-desorption phenomena through catalytic porous networks for efficient diffusion, reactions of desired pathways and elimination of side reactions and waste formation. Building upon exciting ongoing EPSRC funded research activities on 'Designer catalyst for high efficiency biodiesel production', this work proposes a simulation method to refine micro-meso porous kinetic and diffusive parameters to converge with the experimental results and for biodiesel synthesis in continuous oscillatory baffle reactor (OBR) from non-edible oils. © 2012 Elsevier B.V
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