Elias Martinez-Hernandez
University of Oxford
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Elias Martinez-Hernandez.
Bioresource Technology | 2016
Jhuma Sadhukhan; Kok Siew Ng; Elias Martinez-Hernandez
This paper, for the first time, reports integrated conceptual MBCT/biorefinery systems for unlocking the value of organics in municipal solid waste (MSW) through the production of levulinic acid (LA by 5wt%) that increases the economic margin by 110-150%. After mechanical separation recovering recyclables, metals (iron, aluminium, copper) and refuse derived fuel (RDF), lignocelluloses from remaining MSW are extracted by supercritical-water for chemical valorisation, comprising hydrolysis in 2wt% dilute H2SO4 catalyst producing LA, furfural, formic acid (FA), via C5/C6 sugar extraction, in plug flow (210-230°C, 25bar, 12s) and continuous stirred tank (195-215°C, 14bar, 20min) reactors; char separation and LA extraction/purification by methyl isobutyl ketone solvent; acid/solvent and by-product recovery. The by-product and pulping effluents are anaerobically digested into biogas and fertiliser. Produced biogas (6.4MWh/t), RDF (5.4MWh/t), char (4.5MWh/t) are combusted, heat recovered into steam generation in boiler (efficiency: 80%); on-site heat/steam demand is met; balance of steam is expanded into electricity in steam turbines (efficiency: 35%).
Journal of Industrial Ecology | 2017
Elias Martinez-Hernandez; Melissa Yuling Leung Pah Hang; Matthew Leach; Aidong Yang
At the local scale, interconnected production, consumption, waste management, and other man-made technological components interact with local ecosystem components to form a local production system. The purpose of this work is to develop a framework for the conceptual characterization and mathematical modeling of a local production system to support the assessment of process and component options that potentially create symbiosis between industry and ecosystem. This framework has been applied to a case study to assess options for the establishment of a local energy production system that involves a heathland ecosystem, bioenergy production, and wastewater treatment. We found that the framework is useful to analyze the two-way interactions between these components in order to obtain insight into the behavior and performance of the bioenergy production system. In particular, the framework enables exploring the levels of the ecosystem states that allow continuous provisioning of resources in order to establish a sustainable techno-ecological system.
Environmental Science & Technology | 2015
Elias Martinez-Hernandez; Matthew Leach; Aidong Yang
For sustainabilitys sake, the establishment of bioenergy production can no longer overlook the interactions between ecosystem and technological processes, to ensure the preservation of ecosystem functions that provide energy and other goods and services to the human being. In this paper, a bioenergy production system based on heathland biomass is investigated with the aim to explore how a system dynamics approach can help to analyze the impact of bioenergy production on ecosystem dynamics and services and vice versa. The effect of biomass harvesting on the heathland dynamics, ecosystem services such as biomass production and carbon capture, and its capacity to balance nitrogen inputs from atmospheric deposition and nitrogen recycling were analyzed. Harvesting was found to be beneficial for the maintenance of the heathland ecosystem if the biomass cut fraction is higher than 0.2 but lower than 0.6, but this will depend on the specific conditions of nitrogen deposition and nitrogen recycling. With 95% recycling of nitrogen, biomass production was increased by up to 25% for a cut fraction of 0.4, but at the expense of higher nitrogen accumulation and the system being less capable to withstand high atmospheric nitrogen deposition.
Environmental Science & Technology | 2017
Melissa Yuling Leung Pah Hang; Elias Martinez-Hernandez; Matthew Leach; Aidong Yang
Society currently relies heavily on centralized production and large scale distribution infrastructures to meet growing demands for goods and services, which causes socioeconomic and environmental issues, particularly unsustainable resource supply. Considering local production systems as a more sustainable alternative, this paper presents an insight-based approach to the integrated design of local systems providing food, energy, and water to meet local demands. The approach offers a new hierarchical and iterative decision and analysis procedure incorporating design principles and ability to examine design decisions, in both synthesis of individual yet interconnected subsystems and integrated design of resource reuse across the entire system. The approach was applied to a case study on design of food-energy-water system for a locale in the U.K.; resulting in a design which significantly reduced resource consumption compared to importing goods from centralized production. The design process produced insights into the impact of one decision on other parts of the problem, either within or across different subsystems. The result was also compared to the mathematical programming approach for whole system optimization from previous work. It was demonstrated that the new approach could produce a comparable design while offering more valuable insights for decision makers.
Bioresource Technology | 2017
Jhuma Sadhukhan; Elias Martinez-Hernandez
This paper presents material flow and sustainability analyses of novel mechanical biological chemical treatment system for complete valorization of municipal solid waste (MSW). It integrates material recovery facility (MRF); pulping, chemical conversion; effluent treatment plant (ETP), anaerobic digestion (AD); and combined heat and power (CHP) systems producing end products: recyclables (24.9% by mass of MSW), metals (2.7%), fibre (1.5%); levulinic acid (7.4%); recyclable water (14.7%), fertiliser (8.3%); and electricity (0.126MWh/t MSW), respectively. Refuse derived fuel (RDF) and non-recyclable other waste, char and biogas from MRF, chemical conversion and AD systems, respectively, are energy recovered in the CHP system. Levulinic acid gives profitability independent of subsidies; MSW priced at 50Euro/t gives a margin of 204Euro/t. Global warming potential savings are 2.4 and 1.3kg CO2 equivalent per kg of levulinic acid and fertiliser, and 0.17kg CO2 equivalent per MJ of grid electricity offset, respectively.
Computer-aided chemical engineering | 2012
Elias Martinez-Hernandez; Grant M. Campbell; Jhuma Sadhukhan
The selections of product portfolios, processing routes and the combination of technologies to obtain a sustainable biorefinery design according to economic and environmental criteria represent a challenge to process engineering. The aim of this research is to generate a simple but yet robust methodology that assists the process engineers to understand the environmental and economic behaviour of biorefinery systems. The novel Economic Value and Environmental Impact analysis (EVEI) methodology is presented in this paper. EVEI analysis is a tool that emerges from the combination of the value analysis method for the evaluation of economic potential and environmental footprinting for impact analysis. A quick illustration of the methodology in providing insights into the performances of a process network is given by taking a bioethanol plant as case study. The applicability to analyse biorefinery systems for selection of process pathway alternatives is demonstrated by using a Jatropha-based biorefinery case study. The systematisation of the methodology allowed its implementation and integration into a Computer Aided Process Engineering (CAPE) tool in the well known Excel® environment using the built-in VBA facility. This will accelerate the design process allowing focus on the analysis of results and devising alternatives from highly complex integrated process schemes.
Computer-aided chemical engineering | 2015
Melissa Yuling Leung Pah Hang; Elias Martinez-Hernandez; Matthew Leach; Aidong Yang
Centralised production of essential products and services based on fossil fuels and large scale distribution infrastructures have contributed to a plethora of issues such as deterioration of ecosystems, social-economic injustice and depletion of resources. The establishment of localised production systems can potentially reduce unsustainable resource consumption and bring socioeconomic and environmental benefits. The main objective of this work is to develop engineering tools for the rational design of such systems. Production of products and services is characterised as inter-linked subsystems (e.g. food, energy, water and waste). A sequential design approach is developed to design subsystems in turn, with necessary iterations. The process is illustrated through the co-design of energy, water and food production for a case study locale based on a developing eco-town in the UK. This design approach suggested an integrated system based primarily on locally available resources and allowed greater insight into the drivers and constraints on local resource use.
Archive | 2018
Elias Martinez-Hernandez; Kok Siew Ng; Myriam Adela Amezcua Allieri; Jorge Arturo Aburto Anell; Jhuma Sadhukhan
This chapter provides an overview of value-added production using extremophiles as well as the advantages and challenges for process development in a biorefinery concept. The chapter then shows a modeling framework that includes metabolic flux modeling, growth kinetics, and bioreactor models as well as process simulation. The model results are the basis for optimization, economic analysis, and life cycle assessment. The tools are applied to the production of poly-3-hydroxybutyrate (PHB) by using the halophilic bacteria Halomonas sp. The results highlighted the importance of relating models at the various scales and to look at the whole process picture to optimize the economic and environmental performances of the resulting biorefinery process. In the optimized process, the minimum PHB selling price was
Archive | 2018
Elias Martinez-Hernandez; Jhuma Sadhukhan
7.05 per kg and the reduction in greenhouse gas emissions was 90%, with 0.708 kg CO-eq per kg of PHB. These results showed the potential for using halophilic bacteria to make PHB production competitive in terms of economics and environmental impacts. This also shows how extremophile processing will play a key role in making biorefineries more profitable and sustainable.
Applied Energy | 2013
Elias Martinez-Hernandez; Jhuma Sadhukhan; Grant M. Campbell
Abstract This chapter shows how to engineer a competitive waste-biorefinery concept by systematic application of process simulation and integration and technoeconomic and environmental analyses. Reaction-separation process synthesis, heat integration, and effluent treatment and utility system design are shown alongside life-cycle assessment and economic value and environmental impact analysis tools. These are illustrated for levulinic acid production from municipal solid waste (MSW) in the United Kingdom, sugarcane and blue agave bagasse from Mexico, and sago bark from Malaysia. Results demonstrate that targeting at least one high-value chemical product can result in a competitive biorefinery, which can be made sustainable by integrating multiple processes that meet energy and raw material needs internally and environmental regulations, and export any energy excess. Therefore, a biorefinery system must integrate preprocessing and fractionation reactors, product purification, solvent and catalyst recovery, effluent treatment plant, and combined heat and power generation, for sustainability and competitiveness.