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  • Book chapter
    van de Berg D, Jimbo RXJ, Shah N, del Rio-Chanona EAet al., 2023,

    Tractable Data-driven Solutions to Hierarchical Planning-scheduling-control

    , Computer Aided Chemical Engineering, Pages: 649-654

    Using numerical optimization for the hierarchical integration of decision-making units is crucial to provide feasibility and optimality of all levels. However, realistically modelling hierarchical decision-making calls for multilevel formulations, which are numerically intractable and mathematically difficult. In this work, we show how to leverage two data-driven techniques – derivative-free optimization and optimality surrogates – to decrease the computational burden of multilevel problems. We reformulate a tri-level planning-scheduling-control problem into a single-level black-box problem wherein each evaluation calls a scheduling instance with embedded optimal control surrogates. We show that solving this integrated problem instead of the single-level instance leads to changes in the optimal production planning and scheduling sequence, and discuss trade-offs associated with both techniques.
  • Journal article
    Delle Piane C, Ansari H, Li Z, Mata J, Rickard W, Pini R, Dewhurst DN, Sherwood Net al., 2023,

    Influence of Organic Matter Type on Porosity Development in Organic-Rich Shales: Combining Microscopy, Neutron Scattering and Physisorption Approaches

    , Neutron News, Vol: 34, Pages: 8-9, ISSN: 1044-8632
  • Conference paper
    Bird M, Acha S, Escriva EJS, Shah Net al., 2023,

    Data-driven Modelling of Supermarket Refrigeration Systems for Model Predictive Control Applications

    , Pages: 761-768

    With uncertainty in energy markets, and the effects of climate change looming, reducing energy use and operational cost of existing building systems is more important than ever. To this end, this paper presents a grey-box modelling approach to characterise the behaviour of chilled and frozen and coldrooms using basic system specifications and measured data. An overall energy balance is used to devise a discrete state space model for each cabinet, characterised by unknown empirical parameters relating to heat capacity and heat transfer properties. Historical system data from a UK supermarket are used in combination with a genetic algorithm optimisation to determine the optimal empirical parameters for 10 display cases and 10 coldrooms. The resulting cabinet temperature predictions have a good level of accuracy, achieving a root-mean squared error (RMSE) of 0.37°C to 0.98°C. Overall this data-driven approach is effective and efficient in modelling refrigeration systems, and can be easily generalised to any system where historical data is available. Finally, the use of the proposed approach in cost minimisation or demand response application is presented.
  • Book chapter
    Triantafyllou N, Papaiakovou S, Bernardi A, Lakelin M, Shah N, Kokossis A, Papathanasiou MMet al., 2023,

    Machine learning-based decomposition for complex supply chains

    , Computer Aided Chemical Engineering, Pages: 1655-1660

    Personalised medicine products represent a novel category of therapeutics often characterised by bespoke manufacturing lines and dedicated distribution nodes. An example of such products is Chimeric Antigen Receptor (CAR) T-cells, whose manufacturing poses challenges to volumetric scale-up, leading to increased production and supply chain costs. From a modelling perspective, such networks lead to complex large-scale supply chain models that grow exponentially as the demand increases and more therapies are tracked simultaneously throughout the supply chain. In this work, we present a hybrid model that utilizes the potential of machine learning for strategic planning by forecasting optimal supply chain structures and Mixed Integer Linear Programming (MILP) for detailed scheduling. The proposed model is robust to uncertain demand patterns and can reduce the number of linear constraints and binary variables in the original MILP by more than 64.7%.
  • Book chapter
    Soh QY, O'Dwyer E, Acha S, Shah Net al., 2023,

    Modular stochastic optimization for optimal rainwater harvesting system design

    , Computer Aided Chemical Engineering, Pages: 697-702

    Rainwater Harvesting (RWH) systems can serve a dual functionality as a flood mitigation structure as well as providing local water availability. Optimisation-based design strategies must be transferrable enough to incorporate the influence of the local climate and case-specific catchment area characteristics into the design process, which can be a significant endeavour when required for every individual implementation. To increase the accessibility of optimisation methods in the appropriate sizing of RWH systems, this paper presents a modularised optimisation model, where tank components and dynamics are contained as individual blocks. These blocks can then be pieced together to produce a full system model, allowing optimisation models to be easily built for any combination and design of RWH system. This is implemented with a multi-tank RWH system, where an evaluation of the optimised system configuration showed a good balance between the dual objectives of providing improved flood mitigation and local water reuse, in comparison to an existing system derived through alternative sizing strategies.
  • Journal article
    Bian H, Ai L, Heng JYY, Maitland GC, Hellgardt Ket al., 2023,

    Effects of chemical potential differences on methane hydrate formation kinetics

    , Chemical Engineering Journal, Vol: 452, Pages: 1-11, ISSN: 1385-8947

    To underpin the increasing interest in practical applications of gas hydrates, for gas storage and separation for instance, the formation and growth of hydrates at liquid-gas interfaces are of fundamental importance. Although the thermodynamics of hydrate formation has been widely studied and is well understood, the kinetics of these processes is not well characterised. In this work, a high-pressure, low-temperature stirred reactor was used to conduct hydrate formation kinetic studies in a temperature range from 276.5 to 283.5 K and a pressure range from 5 to 10.5 MPa, with a special focus on 1) the impact of agitation conditions on the available water-gas interfacial surface area for mass transfer and growth rate during hydrate formation, and 2) the effect of the chemical potential driving force on the formation rate. Five hydrate growth regimes were identified, with varying degrees of gas mass transfer control across the gas-water interface depending on the extent to which hydrate layers built up at this interface, gas needed to move through solid hydrate layers, and the extent to which the gas was entrained within the water phase. The formation rate in the initial linear growth regime, before the onset of solid hydrate gas mass transfer effects, was found to depend in an essentially exponential manner on the chemical potential difference from the equilibrium state. Semi-empirical models related to Arrhenius-type kinetic models were used to correlate the data, the best of which reproduced the formation rates from the chemical potential differences to within ± 5 %. The approach has general applicability to help determine the balance between kinetic and thermodynamic factors in identifying the optimum pressure-temperature conditions for processes for gas storage, gas separation and other hydrate applications.
  • Journal article
    Low M-YA, Barton LV, Pini R, Petit Cet al., 2023,

    Analytical review of the current state of knowledge of adsorption materials and processes for direct air capture

    , Chemical Engineering Research and Design, Vol: 189, Pages: 745-767, ISSN: 0263-8762

    Significant research interest has been directed towards the deployment of direct air capture (DAC) as a net-negative CO2 emissions technology to help limit global temperature rise to below 2 °C. The scope of this review is to outline the advancement of adsorption-based DAC technologies, as well as to highlight the still-existing data gaps, for both materials’ development and process design in the period 2016 – 2021. On the material side, we highlight the available and missing data on adsorbent properties in relation to what is needed for process modelling and design. We cover material densities, textural properties, thermal properties, adsorption isotherms (i.e. CO2, N2, O2, H2O), adsorption kinetics, and adsorbent stability towards humidity, oxidation, and cycling. On the process side, we provide a detailed look at key process studies conducted in the same time frame by considering the trade-offs to be expected in the design of the adsorption-based DAC process. We focus on process configuration and contactor design, desorption processes, and the need for systematic reporting of key performance indicators to allow for accurate comparisons and benchmarking. Throughout the review, we identify the lack of synergy between material and process development which must be addressed to advance the field of DAC by adsorption.
  • Journal article
    Hoseinpoori P, Woods J, Shah N, 2023,

    An integrated framework for optimal infrastructure planning for decarbonising heating

    , MethodsX, Vol: 10, Pages: 1-18, ISSN: 2215-0161

    This paper presents the HEGIT (Heat, Electricity and Gas Infrastructure and Technology) model for optimal infrastructure planning for decarbonising heating in buildings. HEGIT is an optimisation model based on Mixed Integer Linear Programming. The model co-optimises the integrated operation and capacity expansion planning of electricity and gas grids as well as heating technologies on the consumer side while maintaining the security of supply and subject to different environmental, operational and system-wide constraints. The three main features of the HEGIT model are:• It incorporates an integrated unit commitment and capacity expansion problem for coordinated operation and long-term investment planning of the electricity and gas grids.• It incorporates the flexible operation of heating technologies in buildings and demand response in operation and long-term investment planning of gas and electricity grids.• It incorporates a multi-scale techno-economic representation of heating technologies design features into the whole energy system modelling and capacity planning.These features enable the model to quantify the impacts of different policies regarding decarbonising heating in buildings on the operation and long-term planning of electricity and gas grids, identify the cost-optimal use of available resources and technologies and identify strategies for maximising synergies between system planning goals and minimising trade-offs. Moreover, the multi-scale feature of the model allows for multi-scale system engineering analysis of decarbonising heating, including system-informed heating technology design, identifying optimal operational setups at the consumer end, and assessing trade-offs between consumer investment in heating technologies and infrastructure requirements in different heat decarbonisation pathways.
  • Journal article
    Hofer M, Criscuolo P, Shah N, ter Wal A, Barlow Jet al., 2022,

    Regulatory policy and pharmaceutical innovation in the United Kingdom after Brexit: initial insights

    , Frontiers in Medicine, Vol: 9, ISSN: 2296-858X

    Brexit was presented as an opportunity to promote innovation by breaking free from the European Union regulatory framework. Since the beginning of 2021 the Medicines and Healthcare products Regulatory Agency (MHRA) has operated as the independent regulatory agency for the United Kingdom. The MHRA's regulatory activity in 2021 was analyzed and compared to that of other international regulatory bodies. The MHRA remained reliant on EU regulatory decision-making for novel medicines and there were significant regulatory delays for a small number of novel medicines in the UK, the reasons being so far unclear. In addition, the MHRA introduced innovation initiatives, which show early promise for quicker authorization of innovative medicines for cancer and other areas of unmet need. Longer-term observation and analysis is needed to show the full impact of post-Brexit pharmaceutical regulatory policy.
  • Journal article
    Pan Z, Trusler JPM, 2022,

    Measurement and modelling of the interfacial tensions of CO2 + decane-iododecane mixtures at high pressures and temperatures

    , Fluid Phase Equilibria, Vol: 566, Pages: 1-12, ISSN: 0378-3812

    Experimentally determined interfacial tensions (IFTs) of CO2 and decane-iododecane mixtures are reported, with iododecane mass fractions of 0%, 50%, 70%, 90% and 100% over the temperature range of 298 K to 353 K and at pressures from 1 MPa up to the mixture critical point pressure. Measurements were carried out in a thermostatic high-pressure view cell by means of the pendant drop method. It was observed that the volume of a fresh drop of hydrocarbon initially increased, while the IFT decreased, before reaching equilibrium values. These observations correspond to two key mechanisms of CO2 flooding: oil swelling and IFT reduction. The equilibrium IFTs decrease with increasing pressure isothermally until the mixture critical point pressure is reached. The IFTs also increase with increasing mass fraction of iododecane. An empirical model was developed that is able to represent the experimental results with an overall average absolute deviation of 0.2 mN∙m−1.The IFT data were modeled with the square gradient theory coupled with the volume-translated Peng-Robinson equation of state. The temperature-independent influence parameters of decane and iododecane were regressed from their surface tensions, while the influence parameter of CO2 was taken from literature. The theoretical predictions are in good agreement with the experimental results with an average absolute deviation of 0.4 mN∙m−1. Finally, we extend a group-contribution approach for the binary interaction parameters in the Peng-Robinson equation of state to encompass the CH2I functional group, thereby facilitating application of the modelling approach to other systems comprising CO2 or N2 with iodoalkanes.
  • Report
    Baker W, Acha S, Jennings N, Markides C, Shah Net al., 2022,

    Decarbonisation of buildings: Insights from across Europe

    , Decarbonisation of buildings: Insights from across Europe, Publisher: The Grantham Institute

    This report considers four key challenges facing the UK in reducing carbon emissions from its building stock, and shares insights from across Europe that have the potential to help the UK to decarbonise and increase the energy efficiency of its buildings.
  • Journal article
    Driver JG, Hills T, Hodgson P, Sceats M, Fennell PSet al., 2022,

    Simulation of direct separation technology for carbon capture and storage in the cement industry

    , CHEMICAL ENGINEERING JOURNAL, Vol: 449, ISSN: 1385-8947
    • Cite
    • Citations: 15
  • Journal article
    Weihs GAF, Jones JS, Ho M, Malik RH, Abbas A, Meka W, Fennell P, Wiley DEet al., 2022,

    Life cycle assessment of co-firing coal and wood waste for bio-energy with carbon capture and storage - New South Wales study

    , ENERGY CONVERSION AND MANAGEMENT, Vol: 273, ISSN: 0196-8904
    • Cite
    • Citations: 24
  • Journal article
    O'Dwyer E, Kerrigan EC, Falugi P, Zagorowska MA, Shah Net al., 2022,

    Data-driven predictive control with reduced computational effort and improved performance using segmented trajectories

    , IEEE Transactions on Control Systems Technology, Vol: 31, Pages: 1355-1365, ISSN: 1063-6536

    A class of data-driven control methods has recently emerged based on Willems’ fundamental lemma. Such methods can ease the modeling burden in control design but can be sensitive to disturbances acting on the system under control. In this article, we propose a restructuring of the problem to incorporate segmented prediction trajectories. The proposed segmentation leads to reduced tracking error for longer prediction horizons in the presence of unmeasured disturbance and noise when compared with an unsegmented formulation. The performance characteristics are illustrated in a set-point tracking case study in which the segmented formulation enables more consistent performance over a wide range of prediction horizons. The method is then applied to a building energy management problem using a detailed simulation environment. The case studies show that good tracking performance is achieved for a range of horizon choices, whereas performance degrades with longer horizons without segmentation.
  • Journal article
    Al-Mufachi NA, Shah N, 2022,

    The role of hydrogen and fuel cell technology in providing security for the UK energy system

    , Energy Policy, Vol: 171, Pages: 1-13, ISSN: 0301-4215

    It is not yet well understood how hydrogen and fuel cell technology could perform in the UK energy system (ES) and what influence it may have in contributing towards its security. This article aims to discuss the potential of a hydrogen economy examining its ability to reduce dependency on fossil fuels sourced both domestically and internationally. A snapshot of the hydrogen economy is presented introducing the latest development in hydrogen production technologies and distribution infrastructure. It has been postulated that with the introduction of a CO2 tax, integrating carbon capture and sequestration (CCS) systems with commercial hydrogen production technologies such as steam methane reforming (SMR), coal gasification (CG) and biomass gasification could significantly reduce the levelised cost of hydrogen (LCOH) production. The role of hydrogen and fuel cell technology in coupling the building, transport and industrial sectors has been demonstrated. Decarbonisation of heat in the UK is expected to incur a large cost for transitioning the incumbent network and it is expected that government assistance will be necessary to lessen the burden on consumers. Deployment of fuel cell combined heat and power (CHP) systems and integration into the UK ES could make great strides towards improving its security.
  • Journal article
    Leonzio G, Fennell PS, Shah N, 2022,

    Air-source heat pumps for water heating at a high temperature: State of the art

    , Sustainable Energy Technologies and Assessments, Vol: 54, Pages: 1-22, ISSN: 2213-1388

    Concerns about climate changes are urging the decarbonisation of the energy sector and heat pumps are evaluated for this purpose here. About half of total energy consumption is caused by heating, and the use of heat pumps for this aim is gaining the attention of the research community.This work shows a comprehensive overview of air-source heat pumps used for water heating at a high temperature, with a particular aim to add the supplied heat into the air capture cycle. Air-source heat pumps use different cycles. The literature analysis shows that high temperatures (up to 90 °C) can be easily achieved by trans-critical cycles, while innovative schemes based on heat recuperative solutions might provide hot water up to 99 °C. Very few studies have been conducted about absorption cycles, although these can potentially ensure higher temperatures for the supplied water (up to 115 °C).Although real industrial air source heat pumps achieve a water temperatures lower than those reported above, their utilization is encouraged because, even at high temperatures (up to 100 °C), there are primary energy consumption, cost and carbon dioxide emission savings compared to a traditional boiler, especially when the renewable electricity is used.
  • Working paper
    Küng L, Strunge T, Sunny N, Nie Z, Tariq N, Korre A, Shah N, Van der Spek Met al., 2022,

    An Open-Source Toolkit to Design and Evaluate Net-Zero Pathways for Industrial Clusters
  • Journal article
    Sendi M, Bui M, Mac Dowell N, Fennell Pet al., 2022,

    Geospatial analysis of regional climate impacts to accelerate cost-efficient direct air capture deployment

    , One Earth, Vol: 5, Pages: 1153-1164, ISSN: 2590-3322

    Carbon dioxide (CO2) removal from the atmospheric will be essential if we are to achieve net-zero emissions targets. Direct air capture (DAC) is a CO2 removal method with the potential for large-scale deployment. However, DAC operational costs, and thus deployment potential, is dependent on performance, which can vary under different climate conditions. Here, to further develop our understanding of the impact of regional climate variation on DAC performance, we use high-resolution hourly based global weather profiles between 2016 and 2020 and weighted average capital costs to obtain DAC regional performance and levelized cost of DAC (LCOD). We found that relatively cold and drier regions have favorable DAC performance. Moreover, approximately 25% of the world’s land is potentially unsuitable due to very cold ambient temperatures for a substantial part of the year. For the remaining regions, the estimated LCOD is $320–$540 per tCO2 at an electricity cost of $50 MWh−1. Our results improve the understanding of regional DAC performance, which can provide valuable insights for sustainable DAC deployment and effective climate action.
  • Journal article
    Triantafyllou N, Bernardi A, Lakelin M, Shah N, Papathanasiou Met al., 2022,

    A digital platform for the design of patient-centric supply chains

    , Scientific Reports, Vol: 12, ISSN: 2045-2322

    Chimeric Antigen Receptor (CAR) T cell therapies have received increasing attention, showing promising results in the treatment of acute lymphoblastic leukaemia and aggressive B cell lymphoma. Unlike typical cancer treatments, autologous CAR T cell therapies are patient-specific; this makes them a unique therapeutic to manufacture and distribute. In this work, we focus on the development of a computer modelling tool to assist the design and assessment of supply chain structures that can reliably and cost-efficiently deliver autologous CAR T cell therapies. We focus on four demand scales (200, 500, 1000 and 2000 patients annually) and we assess the tool’s capabilities with respect to the design of responsive supply chain candidate solutions while minimising cost.
  • Journal article
    Ordonez DF, Halfdanarson T, Ganzer C, Shah N, Mac Dowell N, Guillen-Gosalbez Get al., 2022,

    Evaluation of the potential use of e-fuels in the European aviation sector: a comprehensive economic and environmental assessment including externalities

    , SUSTAINABLE ENERGY & FUELS, Vol: 6, Pages: 4749-4764, ISSN: 2398-4902
    • Cite
    • Citations: 15
  • Journal article
    Ganzer C, Pratama YW, Mac Dowell N, 2022,

    The role and value of inter-seasonal grid-scale energy storage in net zero electricity systems

    , International Journal of Greenhouse Gas Control, Vol: 120, Pages: 1-13, ISSN: 1750-5836

    Grid-scale inter-seasonal energy storage and its ability to balance power demand and the supply of renewable energy may prove vital to decarbonise the broader energy system. Whilst there is a focus on techno-economic analysis and battery storage, there is a relative paucity of work on grid-scale energy storage on the system level with the required temporal resolution. Here, we evaluate the potential of power-to-gas-to-power as inter-seasonal energy storage technology. Our results suggest that inter-seasonal energy storage can reduce curtailment of renewable energy, and overcapacity of intermittent renewable power. Importantly, grid scale energy storage assumes a critical role especially when the technology options for dispatchable power are limited. It appears that neither high CAPEX nor low round-trip efficiency preclude the value of the technology per se, however the rate of charge and discharge of the technology emerges as key technical characteristic. This study emphasises the rising importance of balancing seasonality in energy systems characterised by a high penetration of renewable energy, and prompts questions regarding sector integration and resilient decision-making toward a zero-carbon economy.
  • Journal article
    Daniel S, Kis Z, Kontoravdi K, Shah Net al., 2022,

    Quality by design for enabling RNA platform production processes

    , Trends in Biotechnology, Vol: 40, Pages: 1213-1228, ISSN: 0167-7799

    RNA-based products have emerged as one of the most promising and strategic technologies for global vaccination, infectious disease control and future therapy development. The assessment of critical quality attributes, product-process interactions, relevant process analytical technologies, and process modeling capabilities can feed into a robust Quality by Design (QbD) framework for future development, design and control of manufacturing processes. Its implementation will help the RNA technology to reach its full potential and will be central in the development, pre-qualification and regulatory approval of rapid response, disease-agnostic RNA platform production processes.
  • Journal article
    Leonzio G, Fennell PS, Shah N, 2022,

    Modelling and analysis of direct air capture systems in different locations

    , Chemical Engineering Transactions, Vol: 96, Pages: 1-6, ISSN: 1974-9791

    Direct air capture is an important negative emission technology with the aim to reduce carbon dioxide emissions in the atmosphere and to face the current environmental problems such as global warming and climate change. This emerging technology can be based on an adsorption system affected by the used sorbent (physisorbents or chemisorbents). Efficiencies can be measured through the use of key performance indicators that allow a comparison among different processes. An independent analysis was conducted in our previous research to evaluate key performance indicators (total cost, energy consumption, environmental impact and capture capacity) for a direct air capture system based on adsorption using different sorbents (three metal organic frameworks and two amine functionalized sorbents). In this research, the same analysis was extended to several Countries around the world, changing the ambient air temperature according to the yearly average value of the location. Results show that by increasing the air temperature, the adsorption capacity decreases, in a more significant way for metal organic frameworks compared to amine functionalized sorbents. An opposite effect is for energy consumption. Moreover, by increasing the ambient air temperature, a higher environmental impact (in terms of climate change) is present. A trend with the air temperature was not found for total costs. Overall, locations with lower ambient air temperatures are preferred due to a lower environmental impact and energy consumption.
  • Journal article
    High M, Patzschke C, Zheng L, Zeng D, Xiao R, Fennell P, Song Qet al., 2022,

    Hydrotalcite-derived copper-based oxygen carrier materials for efficient chemical-looping combustion of solid fuels with CO2 capture

    , Energy and Fuels, Vol: 36, Pages: 11062-11076, ISSN: 0887-0624

    Chemical-looping combustion (CLC) is a promising technology that utilizes metal oxides as oxygen carriers for the combustion of fossil fuels to CO2 and H2O, with CO2 readily sequestrated after the condensation of steam. Thermally stable and reactive metal oxides are desirable as oxygen carrier materials for the CLC processes. Here, we report the performance of Cu-based mixed oxides derived from hydrotalcite (also known as layered double hydroxides) precursors as oxygen carriers for the combustion of solid fuels. Two types of CLC processes were demonstrated, including chemical looping oxygen uncoupling (CLOU) and in situ gasification (iG-CLC) in the presence of steam. The Cu-based oxygen carriers showed high performance for the combustion of two solid fuels (a lignite and a bituminous coal), maintaining high thermal stability, fast reaction kinetics, and reversible oxygen release and storage over multiple redox cycles. Slight deactivation and sintering of the oxygen carrier occurred after redox cycles at an very high operation temperature of 985 °C. We expect that our material design strategy will inspire the development of better oxygen carrier materials for a variety of chemical looping processes for the clean conversion of fossil fuels with efficient CO2 capture.
  • Journal article
    Acha Izquierdo S, vieira G, Bird M, Shah Net al., 2022,

    Modelling UK electricity regional costs for commercial buildings

    , Energy and Buildings, Vol: 271, Pages: 1-15, ISSN: 0378-7788

    Motivated by rising electricity prices UK non-domestic consumers are being required to develop smart energy management practices. However, most of these consumers lack awareness of the spatial-temporal dynamics of electricity prices and their tariff components. To help overcome these barriers and contribute to energy prices digitalisation, this paper presents a Modelling UK Electricity Regional Costs (MUKERC) framework. A bottom-up methodology that defines all the tariff components and then aggregates them to quantify the cost of a kWh across each half-hour of the day. The framework not only facilitates understanding which tariffs components have a higher impact during different time periods but also depicts how they vary spatially across regions. This model was used to estimate and analyse the evolution of electricity costs from 2017 to 2024. Case studies from buildings in the education sector are showcased depicting their energy costs derived from their load profiles. Results show that the London area has the lowest average prices, while the Northern Wales & Merseyside is the most expensive. From the case studies conducted, peak period charges account for 17% of annual electricity costs (occurring between 4 to 7 p.m.). Winter period charges represented about 53% of the charges. The MUKERC framework showcases the valuable insights data-driven costing models offer as it allows to understand the dynamics of electricity charges and identifies “when” and “where” the cost of electricity is more expensive; thus, supporting the development of bespoke cost-effective energy measures that improve resource efficiency and smart energy management initiatives.
  • Journal article
    Ward A, Pini R, 2022,

    Efficient Bayesian optimisation of industrial-scale pressure-vacuum swing adsorption processes for CO2 capture

    , Industrial and Engineering Chemistry Research, Vol: 61, Pages: 13650-13668, ISSN: 0888-5885

    The design of adsorption systems for separation of CO2/N2 in carbon capture applications is notoriously challenging because it requires constrained multiobjective optimization to determine appropriate combinations of a moderately large number of system operating parameters. The status quo in the literature is to use the nondominated sorting genetic algorithm II (NSGA-II) to solve the design problem. This approach requires 1000s of time-consuming process simulations to find the Pareto front of the problem, meaning it can take days of computational time to obtain a solution. As an alternative approach, we have employed a Bayesian optimization algorithm, the Thompson sampling efficient multiobjective optimization (TSEMO). For constrained productivity/energy usage optimization, we find that the TSEMO algorithm is able to find an essentially identical solution to the design problem as that found using NSGA-II, while requiring 14 times less computational time. We have used the TSEMO algorithm to design a postcombustion carbon capture system for a 1000 MW coal fired power plant using two adsorbent materials, zeolite 13X and ZIF-36-FRL. Although ZIF-36-FRL showed promising process-scale performance in previous studies, we find that the industrial-scale performance is inferior to the benchmark zeolite 13X, requiring a 21% greater cost per tonne of CO2 captured. Finally, we have also tested the performance of the Bayesian design framework when coupled with a data-driven machine learning process modeling framework. In this instance, we find that the incumbent NSGA-II offers better computational performance than the Bayesian approach by a factor of 3.
  • Journal article
    Broukos P, Fragkogios A, Shah N, 2022,

    A Linearized Mathematical Formulation for Combined Centralized and Distributed Waste Water Treatment Network Design

    , Operations Research Forum, Vol: 3

    Waste water treatment (WWT) is a very important issue affecting both the environment and public health in the twenty-first century. The increasing earth’s population together with the growing urbanism leads to the need of redesigning effective WWT. In this paper, the problem of optimal Waste Water Treatment Network Design (WWTND) is addressed. To this end, various parameters affecting the problem have been taken into consideration, such as the distance between the residential areas and the treatment plants, estimations for future population of towns and costs of expanding existing network or building a new one. The last parameter of cost has a lot of components (pipeline cost, treatment plant cost, etc.), all of which are non-linear functions depending on the amount of waste water produced and treated within the network. The authors have developed a mathematical model for the solution of WWTND problem and have applied piecewise linearization in order to deal with the non-linear terms. The developed model has been implemented on an area in Luxemburg, for which data were collected. The results prove the model’s validity and usefulness, while its solution is computationally affordable.
  • Journal article
    Bird M, Daveau C, O'Dwyer E, Acha S, Shah Net al., 2022,

    Real-world implementation and cost of a cloud-based MPC retrofit for HVAC control systems in commercial buildings

    , Energy and Buildings, Vol: 270, Pages: 1-13, ISSN: 0378-7788

    Many businesses are looking for ways to improve the energy and carbon usage of their buildings, particularly through enhanced data collection and control schemes. In this context, this paper presents a case study of a food-retail building in the UK, detailing the design, installation and cost of a generalisable model predictive control (MPC) framework for its Heating, Ventilation and Air Conditioning (HVAC) system. The hardware/software solution to collect relevant data, as well as the formulation of the MPC scheme, is presented. By utilising cloud-based microservices, this approach can be applied to all modern building management systems with little upfront capital, and an ongoing monthly cost as low as $6.39/month. The MPC scheme calculates the optimal temperature setpoint required for each Air-Handling Unit (AHU) to minimise its overall cost or carbon usage, while ensuring thermal comfort of occupants. Its performance is then compared to the existing legacy controller using a simulation the building’s thermal behaviour. When simulated across two months the MPC approach performed better, able to achieve the same thermal comfort for a lower overall cost. The economic optimisation resulted in an energy saving of 650 kWh, with an associated cost savings of $240 (1.7% compared to the baseline), while the carbon optimisation gave negligible CO2 savings due to the inability of the building to shift heating to low-carbon periods. Findings from this study indicate the potential for improving building performance via MPC strategies but impact will depend on specific building attributes.
  • Journal article
    Li K, Acha Izquierdo S, Sunny N, Shah Net al., 2022,

    Strategic transport fleet analysis of heavy goods vehicle technology for net-zero targets

    , Energy Policy, Vol: 168, ISSN: 0301-4215

    This paper addresses the decarbonisation of the heavy-duty transport sector and develops a strategy towards net-zero greenhouse gas (GHG) emissions in heavy-goods vehicles (HGVs) by 2040. By conducting a literature review and a case study on the vehicle fleet of a large UK food and consumer goods retailer, the feasibilities of four alternative vehicle technologies are evaluated from environmental, economic, and technical perspectives. Socio-political factors and commercial readiness are also examined to capture non-technical criteria that influences decision-makers. Strategic analysis frameworks such as PEST-SWOT models were developed for liquefied natural gas, biomethane, electricity and hydrogen to allow a holistic comparison and identify their long-term deployment potential. Fossil and renewable natural gas are found to be effective transitional solutions. Technology innovation is needed to address range and payload limitations of electric trucks, whereas government and industry support are essential for a material deployment of hydrogen in the 2030s. Given the UK government’s plan to phase out new diesel HGVs by 2040, fleet operators should commence new vehicle trials by 2025 and replace a considerable amount of their lighter diesel trucks with zero-emission vehicles by 2030, and the remaining heavier truck fleet by 2035.
  • Journal article
    Hoseinpoori P, Olympios AV, Markides CN, Woods J, Shah Net al., 2022,

    A whole-system approach for quantifying the value of smart electrification for decarbonising heating in buildings

    , Energy Conversion and Management, Vol: 268, Pages: 1-24, ISSN: 0196-8904

    This paper uses a whole system approach to examine system design and planning strategies that enhance the system value of electrifying heating and identify trade-offs between consumers’ investment and infrastructure requirements for decarbonising heating in buildings. We present a novel integrated model of heat, electricity and gas systems, HEGIT, to investigate different heat electrification strategies using the UK as the case study from two perspectives: (i) a system planning perspective regarding the scope and timing of electrification; and (ii) a demand-side perspective regarding the operational and investment schemes on the consumer side. Our results indicate that complete electrification of heating increases peak electricity demand by 170%, resulting in a 160% increase in the required installed capacity in the electricity grid. However, this effect can be moderated by implementing smart demand-side schemes. Grid integration of heat pumps combined with thermal storage at the consumer-end was shown to unlock significant potential for diurnal load shifting, thereby reducing the electricity grid reinforcement requirements. For example, our results show that a 5 b£ investment in such demand-side flexibility schemes can reduce the total system transition cost by about 22 b£ compared to the case of relying solely on supply-side flexibility. In such a case, it is also possible to reduce consumer investment by lowering the output temperature of heat pumps from 55 °C to 45 °C and sharing the heating duty with electric resistance heaters. Furthermore, our results suggest that, when used at a domestic scale, ground-source heat pumps offer limited system value since their advantages (lower peak demand and reduced variations in electric heating loads) can instead be provided by grid-integration of air-source heat pumps and increased thermal storage capacity at a lower cost to consumers and with additional flexibility benefits for the electricity gr

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