Publications
677 results found
Giarola S, Shah N, 2013, Techno-economic and environmental assessment of ionic liquid-based biorefineries, Pages: 127-128
Giarola S, Shah N, 2013, Techno-economic and environmental assessment of ionic liquid-based biorefineries, Pages: 338-339
Shah N, 2013, Modelling urban energy systems, Urban Energy Systems: An Integrated Approach, Pages: 139-156, ISBN: 9780415529013
The importance of computer modelling in urban energy systems can be seen as twofold. First, it allows one to analyse and understand the current state of these systems. But also, and perhaps more importantly with regards to sustainability, it allows one to ‘predict, prescribe and invent’ the urban systems of the future (Batty 1976). Clearly however, ‘exact’ modelling of urban systems, on the scale of building-to-building or finer detail, is not feasible, as an enormous amount of information would be required to construct a complete urban model. It would also likely not be desirable, as it would limit the applicability of the derived model (e.g. to a specific city), with little scope for generalization. Therefore any urban energy systems model developed will be an idealization or simplification of reality; the extent depends on model complexity and the approaches used. Models can range from the highly aggregated to disaggregated, partial to general, static to dynamic, and so on, depending on their intended use.
Keirstead J, Shah N, 2013, Conclusion, Urban Energy Systems: An Integrated Approach, Pages: 272-277, ISBN: 9780415529013
In the preface, we noted that this book represents something of a milestone. When we first began working on urban energy systems in 2006, a good part of the first year was spent scouring the literature for inspiration and advice. Although we eventually did uncover many valuable studies, it was difficult at first to find much of this material. There’s no Journal of Urban Energy Systems and review articles tended to focus on specific issues, like district energy systems or ‘energy ladder’ development transitions, without an overarching framework. Although this makes sense when one thinks about the number of disciplines that have contributions to make in this field, the lack of a ‘one-stop-shop’ does make it difficult for new researchers to begin exploring the topic.
Mac Dowell N, Samsatli NJ, Shah N, 2013, Dynamic modelling and analysis of an amine-based post-combustion CO₂ capture absorption column, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 12, Pages: 247-258, ISSN: 1750-5836
Pantaleo AM, Shah N, Keirstead J, 2013, Bioenergy and other renewables in urban energy systems: Potentials, conversion routes and future trends, Urban Energy Systems: An Integrated Approach, Pages: 96-117, ISBN: 9780415529013
As described in Chapter 2, cities primarily import high-quality raw fuels and export their wastes. This allows them to maintain high degrees of order within constrained spaces, a necessity for urban living. However, that is not to say that cities only import energy resources such as natural gas or electricity. Urban renewable energy sources that is, renewable energy sources that lie predominantly within the urban boundary or the near hinterland are an option for all cities, particularly those at early stages of development where lower energy demands and a lack of distribution infrastructure may make local resources an attractive option.a.
Shah N, Keirstead J, 2013, The growing importance of urban energy systems, Urban Energy Systems: An Integrated Approach, Pages: 3-13, ISBN: 9780415529013
Urban energy systems are a somewhat neglected and unrecognized part of our cities. Yet without reliable and abundant supplies of electricity, heating, transport fuel, and other services, all functioning smoothly behind the scenes, the more visible elements of a city would not be possible. The bright lights of central shopping districts would grow dim, the flow of urban traffic would grind to a halt, and our homes would not be as comfortable. This book is an exploration of these systems and the links they have with our lives, economies and the environment. In this first chapter, we introduce the subject by defining urban energy systems and highlighting major global trends in urbanization and resource consumption, as these basic statistics and working hypotheses have been the motivation for the research presented here.
Alhajaj A, Mac Dowell N, Shah N, 2013, Multiscale Design and Analysis of CO₂ Capture, Transport and Storage Networks, Energy Procedia, Vol: 37, Pages: 2552-2561, ISSN: 1876-6102
Hayes-Labruto L, Schillebeeckx SJD, Workman M, et al., 2013, Contrasting Perspectives on China's Rare Earth Policies: Reframing the Debate through a Stakeholder Lens, Energy Policy
This article critically compares China’s rare earth policy with perspectives upheld in the rest of the world (ROW). We introduce rare earth elements and their importance for energy and present how China and the ROW are framing the policy debate. We find strongly dissonant views with regards to motives for foreign direct investment, China’s two-tiered pricing structure and its questionable innovation potential. Using the metaphor of “China Inc.”, we compare the Chinese government to a socially responsible corporation that aims to balance the needs of its internal stakeholders with the demands from a resource-dependent world. We find that China’s internal stakeholders have more power and legitimacy in the REE debate than the ROW and reconceptualise various possible mitigation strategies that could change current international policy and market dynamics. As such, we aim to reframe the perspectives that seem to govern the West and argue in favour of policy formation that explicitly acknowledges China’s triple bottom line ambitions and encourages the ROW to engage with China in a more nuanced manner.
Shah N, Vallejo L, Cockerill T, et al., 2013, Halving Global CO2 Emissions: Technologies and Costs, Publisher: Imperial College London
Acha Izquierdo S, Shah N, 2012, Optimal Lighting Control Strategies in Supermarkets for Energy Efficiency Applications via Digital Dimmable Technology, ECOS 2012, Publisher: Firenze University Press
Electricity consumption in the UK commercial sector accounts for 19% of total annual electricity demand.This implies any step taken towards energy efficiency applications for commercial buildings can generateimportant reductions in both energy use and carbon emissions. Sainsbury’s supermarkets, one of the UKslargest grocers, recognises the challenges climate change brings to businesses and hence is conductingefforts to reduce the operational carbon footprint of their stores. Lighting in stores is an essential service andis an important component of a stores power demand; ranging from 15 to 35% based on design features.This paper details the innovative lighting control application Sainsbury’s is currently employing in its newstores with the objective to maximise the benefits digital dimmable technology possesses. Basic lightingconcepts are described which explain the priorities supermarkets have when using this service, while thetradeoffs of using digital signal interface (DSI) controls are also discussed. The non-linear relationshipbetween DSI settings, lux drawn from ballasts, and power consumed by the system are showcased as aproper understanding of this concept is paramount in achieving energy savings. In addition, using aSainsbury’s 3,300 m2 eco-store, a thorough case study is presented in which various lighting strategysettings are applied; having very attractive results in monetary, energy, and environmental metrics withoutbeing detrimental to the shopping experience. Hence, it is proven digital dimmable technology controls caneffectively provide 20 to 25% savings in lighting services if sensors and settings are established properly.Furthermore, due to the robust and fast response capability digital dimming offers, the authors argue thistechnology is suitable for demand side management applications that can greatly benefit the operability ofthe grid and as a consequence provide an additional revenue stream for businesses in a smart-gridenviro
Akgul O, Dowell NM, Shah N, et al., 2012, Optimisation of bioelectricity supply chains, AIChE 2012 - 2012 AIChE Annual Meeting, Conference Proceedings
There has been a growing interest in the development and use of renewable energy technologies in the recent years to tackle major problems such as global climate change, depleting fossil fuel resources and increasing oil prices. Among the renewable energy technologies, bioenergy is considered to be a promising near-term solution. Bioenergy is obtained from the conversion of a variety of biomass feedstock including wood, dedicated energy crops, food crops and biomass waste. This diversity of types of biomass offers a significant advantage in terms of contributing to energy security through a diversified energy mix. Bioenergy can be used for different purposes such as dispatchable electricity generation, high grade heat and production of liquid biofuels. Mandates and targets have been set around the globe to promote the use of renewable energy. The UK is committed to supplying 15% of its energy demand from renewable resources and reduce its greenhouse gas emissions by at least 34% by 2020. Moreover, when combined with CO2 capture and storage, the co-firing of biomass with fossil fuels leads to CO2 negative energy. This is important in the context of mitigating anthropogenic CO2 emissions, and eventually reducing atmospheric CO2 concentration. Therefore, bioenergy is expected to play an important role as a part of the renewable energy mix to meet these long term renewables and emissions reductions targets. A bioenergy supply chain is a multi-echelon network consisting of biomass cultivation sites, bioenergy production facilities and demand centres. Application of supply chain optimisation to such systems means consideration of all these nodes in the chain as well as transport of biomass and bioenergy between these nodes. This work presents a spatially-explicit optimisation framework for a bioenergy supply chain network based on a "neighbourhood flow" approach. Linear models of co-fired coal-based power plants with amine-based CO2 capture have been derived fro
Zhang D, Samsatli NJ, Hawkes AD, et al., 2012, Fair electricity transfer price and unit capacity selection for microgrids, Energy Economics, Vol: In Press, ISSN: 0140-9883
Microgrids are defined as an area of electricity distribution network that can operate autonomously from the rest of the network. In order to achieve the best economic outcomes, the participants in a microgrid can benefit from cooperation in microgrid design and operation. In this paper, a mathematical programming formulation is presented for fair, optimised cost distribution amongst participants in a general microgrid. The proposed formulation is based on the Game-theory Nash bargaining solution approach for finding optimal multi-partner cost levels subject to given upper bounds on the equivalent annual costs. The microgrid planning problem concerning the fair electricity transfer price and unit capacity selection is first formulated as a mixed integer non-linear programming model. Then, a separable programming approach is applied to reform the resulting mixed integer non-linear programming model to a mixed integer linear programming form. The model is applied to a case study with a microgrid involving five participants.
Arce A, Mac Dowell N, Shah N, et al., 2012, Flexible operation of solvent regeneration systems for CO₂ capture processes using advanced control techniques: Towards operational cost minimisation, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 11, Pages: 236-250, ISSN: 1750-5836
Liu S, Shah N, Papageorgiou LG, 2012, Multiechelon supply chain planning with sequence-dependent changeovers and price elasticity of demand under uncertainty, AICHE JOURNAL, Vol: 58, Pages: 3390-3403, ISSN: 0001-1541
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- Citations: 16
Acha S, van Dam KH, Shah N, 2012, Modelling spatial and temporal agent travel patterns for optimal charging of electric vehicles in low carbon networks, 2012 IEEE Power and Energy Society General Meeting, Publisher: IEEE, Pages: 1-8
The ability to determine optimal charging profiles of electric vehicles (EVs) is paramount in developing an efficient and reliable smart-grid. However, so far the level of analysis proposed to address this issue lacks combined spatial and temporal elements, thus making mobility a key challenge to address for a proper representation of this problem. This paper details the principles applied to represent optimal charging of EVs by employing an agent-based model that simulates the travelling patterns of vehicles on a road network. The output data is used as a reliable forecast so an optimal power flow model can devise optimal charging scenarios of EVs in a local electrical network. The effectiveness of the model is illustrated by presenting a multi-day case study in an urban area. Results show a high level of detail and variability in EV charging when a present-day carbon fuel mix is compared to one with lower carbon intensity.
Akgul O, Shah N, Papageorgiou LG, 2012, An optimisation framework for a hybrid first/second generation bioethanol supply chain, 21st European Symposium on Computer-Aided Process Engineering (ESCAPE), Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 101-114, ISSN: 0098-1354
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- Citations: 104
Akgul O, Shah N, Papageorgiou LG, 2012, Economic optimisation of a UK advanced biofuel supply chain, BIOMASS & BIOENERGY, Vol: 41, Pages: 57-72, ISSN: 0961-9534
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- Citations: 85
Keirstead JE, Samsatli N, Shah N, et al., 2012, The impact of CHP (combined heat and power) planning restrictions on the efficiency of urban energy systems, Energy, Vol: 41, Pages: 93-103
Cities account for approximately two-thirds of global primary energy consumption and have large heat and power demands. CHP (combined heat and power) systems offer significant primary energy-efficiency gains and emissions reductions, but they can have high upfront investment costs and create nuisance pollution within the urban environment. Urban planners therefore need to understand the tradeoffs between limitations on CHP plant size and the performance of the overall energy system. This paper uses a mixed-integer linear programming model to evaluate urban energy system designs for a range of city sizes and technology scenarios. The results suggest that the most cost-effective and energy-efficient scenarios require a mix of technology scales including CHP plants of appropriate size for the total urban demand. For the cities studied here (less than 200,000 people), planning restrictions that prevent the use of CHP technologies could lead to total system cost penalties of 2% (but with significantly different cost structures) and energy-efficiency penalties of up to 24% when measured against a boiler-only business-as-usual case.
Keirstead JE, Samsatli NJ, Pantaleo AM, et al., 2012, Evaluating biomass energy strategies for a UK eco-town with an MILP optimization model, Pages: 306-316
Recent years have shown a marked interest in the construction of eco-towns, showcase developments intended to demonstrate the best in ecologically-sensitive and energy-efficient construction. This paper examines one such development in the UK and considers the role of biomass energy systems. We present an integrated resource modelling framework that identifies an optimized low-cost energy supply system including the choice of conversion technologies, fuel sources, and distribution networks. Our analysis shows that strategies based on imported wood chips, rather than locally converted forestry residues, burned in a mix of ICE and ORC combined heat and power facilities offer the most promise. While there are uncertainties surrounding the precise environmental impacts of these solutions, it is clear that such biomass systems can help eco-towns to meet their target of an 80% reduction in greenhouse gas emissions.
Mokhtar M, Ali MT, Khalilpour R, et al., 2012, Solar-assisted Post-combustion Carbon Capture feasibility study, APPLIED ENERGY, Vol: 92, Pages: 668-676, ISSN: 0306-2619
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- Citations: 91
Khor CS, Chachuat B, Shah N, 2012, A superstructure optimization approach for water network synthesis with membrane separation-based regenerators, European Symposium of Computer Aided Process Engineering - 21, Publisher: Elsevier, Pages: 48-63, ISSN: 0098-1354
This work addresses the problem of water network synthesis. We propose a superstructure with fixed topology for a water network that consists of three layers, similar to a pooling problem: sources for reuse/recycle; regenerators for contaminants removal; and sinks for acceptance of water for reuse/recycle. The superstructure encompasses multiple freshwater sources, membrane separation-based partitioning regenerators of the industrially favored ultrafiltration and reverse osmosis, and sinks for incineration and deep ocean discharge. A mixed-integer nonlinear program is formulated based on this superstructure to determine the optimal interconnections in terms of total flowrates and contaminant concentrations. The main decisions include determining the split fractions of the source flowrates, extents of regeneration, and mixing ratios of the sources and regenerated streams subject to compliance with the maximum allowable inlet contaminant concentration limits of the sinks and discharge regulations. We also develop linear models for the membrane regenerators that admit a more general expression for the retentate stream concentration based on liquid-phase recovery factors and removal ratios. Computational studies are performed using GAMS/BARON on an industrially significant case study of a petroleum refinery water system. We incorporate linear logical constraints using 0–1 variables that enforce certain design and structural specifications to tighten the model formulation and enhance solution convergence. A globally optimal water network topology is attained that promotes a 27% savings equivalent to about $218,000/year reduction in freshwater use.
Giarola S, Shah N, Bezzo F, 2012, A comprehensive approach to the design of ethanol supply chains including carbon trading effects, BIORESOURCE TECHNOLOGY, Vol: 107, Pages: 175-185, ISSN: 0960-8524
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- Citations: 105
Almansoori A, Shah N, 2012, Design and operation of a stochastic hydrogen supply chain network under demand uncertainty, INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, Vol: 37, Pages: 3965-3977, ISSN: 0360-3199
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- Citations: 96
Khor CS, Shah N, Mahadzir S, et al., 2012, Optimisation of petroleum refinery water network systems retrofit incorporating reuse, regeneration and recycle strategies, CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Vol: 90, Pages: 137-143, ISSN: 0008-4034
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- Citations: 15
Jennings M, Shah N, Fisk D, 2012, Optimising the arrangement of finance towards large scale refurbishment of housing stock using mathematical programming and optimisation, Proceedings of the 25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012, Vol: 7, Pages: 213-228
The U.K. will require significant refurbishment interventions to the existing building stock if her 2050 greenhouse gas emissions targets are to be met. In parallel, the current economic recession is forcing some investors and creditors to look to new strategies of achieving healthy returns on property assets. The research presented in this paper seeks to analyse these problems using optimisation. A mixed integer linear programming model is presented for arranging the finance for large scale refurbishment schemes. The objective function minimises the costs of arranging finance. This model feeds into a technology urban resource network model, which allows for optimised statements of the refurbishment actions to be performed, their timing, and their quantity. An example of an urban area seeking to reduce its housing heating emissions is presented. Results suggest that division of finance, technology capacity, and organisational capacity by tenure is more appropriate than simpler representations. Overall, the optimisation models presented are thought to offer a robust method going forward for the arrangement of finance towards energy efficient refurbishment of housing stock at the large scale.
Seong Khor C, Chachuat B, Shah N, 2012, Optimal water network synthesis with membrane separation-based regenerators, Vol: 30, Pages: 36-40, ISSN: 1570-7946
This article is concerned with the water network synthesis problem. We propose a superstructure that consists of three layers similar to a pooling problem: sources for reuse/recycle; regenerators for contaminants removal; and sinks for acceptance of water for direct or regeneration-reuse/recycle. The superstructure accounts for membrane separation-based regenerators such as ultrafiltration and reverse osmosis. Linear models are developed for the membrane regenerators. A MINLP is then formulated based on the superstructure to determine the optimal interconnections in terms of total flowrates and contaminant concentrations. Computational experiments are performed using GAMS/BARON on an industrial case study of a petroleum refinery water system. We include model-tightening linear logical constraints to enhance solution convergence, resulting in a globally optimal water network that promotes 27% savings in freshwater use. © 2012 Elsevier B.V.
Alhajaj A, Shah N, 2012, Design and analysis of CO2 capture, transport, and storage networks, Society of Petroleum Engineers - Carbon Management Technology Conference 2012, Vol: 2, Pages: 813-817
The large-scale deployment of carbon capture, transport and storage (CCTS) systems will be capital intensive and complex. Therefore, it is necessary to design a network infrastructure that can meet a specific CO2 reduction target and is at the same time optimized to minimize cost and operation problems. The objective of this work is to develop a multiscale modeling approach that uses flue gas characterization data as an input to simulate and size a post-combustion capture plant model. The profile of the bare capturing cost of CO2 against degree of capture is used in designing and analyzing the cost optimal CO2 infrastructure layout that matches CO2 sources and sinks in capacity and time. This will help generate insights of whole-system integration issues and its performance as function of design variables: Thus the whole system is optimized rather than optimizing individual components, which leads to sup-optimal CCTS design. Typically, researchers assume a cost associated with a pre-specified 90% degree of capture, which is claimed to be the cost optimal capture plant. The results of designing and analyzing cost optimal CCTS networks for a UAE case study show that the cost optimal degree of capture is a site specific factor that depends on the flue gas characteristics and proximity to transportation networks and geological storage that can accommodate certain amount of CO2 per year. Copyright 2012, Carbon Management Technology Conference.
Khor CS, Chachuat B, Shah N, 2012, Optimal water network synthesis with detailed membrane-based regenerator models, 11th International Symposium on Process Systems Engineering (PSE), Publisher: ELSEVIER SCIENCE BV, Pages: 1457-1461, ISSN: 1570-7946
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- Citations: 1
Mehdizadeh A, Shah N, Raikar N, et al., 2012, Food supply chain planning and quality optimization approach, 22nd European Symposium on Computer Aided Process Engineering (ESCAPE), Publisher: ELSEVIER SCIENCE BV, Pages: 1172-1176, ISSN: 1570-7946
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