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  • CONFERENCE PAPER
    Abolghasemi M, Piggott MD, Spinneken J, Vire A, Cotter CJ, Crammond Set al.,

    Simulating tidal turbines with mesh optimisation and RANS turbulence models

    , 2015 European Wave and Tidal Energy Conference
  • CONFERENCE PAPER
    Acha S, van Dam KH, Keirstead J, Shah Net al.,

    Integrated modelling of agent-based electric vehicles into optimal power flow studies

    , Frankfurt, Germany
  • CONFERENCE PAPER
    Ahmad F, Murphy W, Lawrence JA, Hencher Set al.,

    Strength Mobilisation of Rock Masses in Relation to Deep Seated Landslide

    , Geophysical Research Abstracts 17, EGU2015, 8151
  • JOURNAL ARTICLE
    Avdis A, Jacobs CT, Hill J, Piggott MD, Gorman GJet al.,

    Shoreline and Bathymetry Approximation in Mesh Generation for Tidal Renewable Simulations

    Due to the fractal nature of the domain geometry in geophysical flowsimulations, a completely accurate description of the domain in terms of acomputational mesh is frequently deemed infeasible. Shoreline and bathymetrysimplification methods are used to remove small scale details in the geometry,particularly in areas away from the region of interest. To that end, a novelmethod for shoreline and bathymetry simplification is presented. Existingshoreline simplification methods typically remove points if the resultantgeometry satisfies particular geometric criteria. Bathymetry is usuallysimplified using traditional filtering techniques, that remove unwanted Fouriermodes. Principal Component Analysis (PCA) has been used in other fields toisolate small-scale structures from larger scale coherent features in a robustway, underpinned by a rigorous but simple mathematical framework. Here wepresent a method based on principal component analysis aimed towardssimplification of shorelines and bathymetry. We present the algorithm in detailand show simplified shorelines and bathymetry in the wider region around theNorth Sea. Finally, the methods are used in the context of unstructured meshgeneration aimed at tidal resource assessment simulations in the coastalregions around the UK.

  • JOURNAL ARTICLE
    Barral N, Knepley MG, Lange M, Piggott MD, Gorman GJet al.,

    Anisotropic mesh adaptation in Firedrake with PETSc DMPlex

    Despite decades of research in this area, mesh adaptation capabilities arestill rarely found in numerical simulation software. We postulate that theprimary reason for this is lack of usability. Integrating mesh adaptation intoexisting software is difficult as non-trivial operators, such as error metricsand interpolation operators, are required, and integrating available adaptiveremeshers is not straightforward. Our approach presented here is to firstintegrate Pragmatic, an anisotropic mesh adaptation library, into DMPlex, aPETSc object that manages unstructured meshes and their interactions withPETSc's solvers and I/O routines. As PETSc is already widely used, this willmake anisotropic mesh adaptation available to a much larger community. As ademonstration of this we describe the integration of anisotropic meshadaptation into Firedrake, an automated Finite Element based system for theportable solution of partial differential equations which already uses PETScsolvers and I/O via DMPlex. We present a proof of concept of this integrationwith a three-dimensional advection test case.

  • CONFERENCE PAPER
    Bixby H, Fecht D, Fortunato L, Hodgson Set al.,

    Are greener cities healthier? An investigation into the association between green space coverage and health at the city level, in England

    , joint meeting of the International Society for Environmental Epidemiology (ISEE), the International Society of Exposure Science (ISES), and the International Society of Indoor Air Quality and Climate (ISIAQ)., Publisher: National Institute of Environmental Health Sciences (NIEHS), ISSN: 1552-9924
  • CONFERENCE PAPER
    Busby JP, Senfaute G, Gourry JC, Lawrence JA, Pederson SAS, Mortimore RNet al.,

    Developing tools for the prediction of catastrophic coastal cliff collapse

    , In: Proceedings of the 7th International Symposium – Delivering Sustainable Coasts: Connecting Science and Policy, Pages: 596-601
  • JOURNAL ARTICLE
    Funke SW, Kramer SC, Piggott MD,

    Design optimisation and resource assessment for tidal-stream renewable energy farms using a new continuous turbine approach

    , Renewable Energy, ISSN: 1879-0682

    This paper presents a new approach for optimising the design of tidal stream turbine farms. In this approach, the turbine farm is represented by a turbine density function that specifies the number of turbines per unit area and an associated continuous locally-enhanced bottom friction field. The farm design question is formulated as a mathematical optimisation problem constrained by the shallow water equations and solved with efficient, gradient-based optimisation methods. The resulting method is accurate, computationally efficient, allows complex installation constraints, and supports different goal quantities such as to maximise power or profit. The outputs of the optimisation are the optimal number of turbines, their location within the farm, the overall farm profit, the farm's power extraction, and the installation cost.We demonstrate the capabilities of the method on a validated numerical model of the Pentland Firth, Scotland. We optimise the design of four tidal farms simultaneously, as well as individually, and study how farms in close proximity may impact upon one another.

  • JOURNAL ARTICLE
    Goode AE, Hine NDM, Chen S, Bergin SD, Shaffer MSP, Ryan MP, Haynes PD, Porter AE, McComb DWet al.,

    Mapping functional groups on oxidised multi-walled carbon nanotubes at the nanometre scale

    , Chemical Communications, ISSN: 1364-548X
  • CONFERENCE PAPER
    Green RJ, Staffell I,

    Storage in the electricity market

    , International Ruhr Energy Conference 2015
  • CONFERENCE PAPER
    Heuberger CF, Staffell I, Shah N, Mac Dowell Net al.,

    Levelised Value of Technology - A Systemic Approach to Technology Valuation

    , 26th European Symposium on Computer Aided Process Engineering - ESCAPE 26
  • JOURNAL ARTICLE
    Kline KL, Msangi S, Dale VH, Woods J, Souza GM, Osseweijer P, Clancy JS, Hilbert JA, Mugera HK, McDonnell PC, Johnson FXet al.,

    Reconciling biofuels and food security: priorities for action

    , Global Change Biology Bioenergy, ISSN: 1757-1693

    Addressing the challenges of understanding and managing complex interactions among food security, biofuels, and resource management requires a focus on specific contextual problems and opportunities. The United Nations’ 2030 Sustainable Development Goals prioritize food and energy security; bioenergy plays an important role in achieving both goals. Effective food security programs begin by clearly defining the problem and asking, “What can be done to effectively assist people at high risk?” Headlines and cartoons that blame biofuels for food insecurity may reflect good intentions but mislead the public and policy makers because they obscure the main drivers of local food insecurity and ignore opportunities for biofuels to contribute to solutions. Applying sustainability guidelines to bioenergy will help achieve near- and long- term goals to eradicate hunger. Priorities for achieving successful synergies between bioenergy and food security include (1) clarifying communications with clear and consistent terms, (2) recognizing that food and bioenergy need not compete for land and instead, need to be integrated with improved resource management, (3) investing in innovations to build capacity and infrastructure such as rural agricultural extension and technology, (4) promoting stable prices that incentivize local production, (5) adopting flex crops that can provide food along with other products and services to society, and (6) engaging stakeholders in identifying and assessing specific opportunities for biofuels to improve food security. Systematic monitoring and analysis to support adaptive management and continual improvement are essential elements to build synergies and help society equitably meet growing demands for both food and energy.

  • JOURNAL ARTICLE
    Lawrence JA,

    Soil and Rock Description in Engineering Practice, D. Norbury: Book review

    , International Journal of Rock Mechanics & Mining Sciences, Pages: 1381-1381
  • JOURNAL ARTICLE
    Lawrence JA,

    Informing chalk cliff recession management decisions

    , Civil Engineering Year Book 2010, Pages: 17-18
  • JOURNAL ARTICLE
    Mao F, Clark J, Karpouzoglou T, Dewulf A, Buytaert W, Hannah Det al.,

    A conceptual framework for assessing socio-hydrological resilience under change

    , Hydrology and Earth System Sciences Discussions, Pages: 1-26
  • CONFERENCE PAPER
    Mechleri E, fennell P, Mac Dowell N,

    Flexible operation strategies for coal- and gas-CCS power stations under the UK and USA markets

    , 13th Greenhouse Gas Control Technologies (GHGT) conference
  • CONFERENCE PAPER
    Mechleri E, rivotti P, mac Dowell N, thornhill Net al.,

    Flexibility issues and controllability analysis of a post-combustion CO2 capture plant integrated with a natural gas power plant

    , 8th Trondheim Conference on CO2 Capture, Transport and Storage (TCCS-8)
  • JOURNAL ARTICLE
    Nixon CW, McNeill LC, Bull JM, Bell RE, Gawthorpe RL, Henstock TJ, Christodoulou, Ford M, Taylor B, Sakellariou D, Ferentinos G, Papatheodorou G, Leeder M, Collier RELI, Goodliffe A, Sachpazi M, Kranis Het al.,

    Rapid spatio-temporal variations in rift structure during development of the Corinth Rift, central Greece

    , Tectonics, ISSN: 1944-9194
  • JOURNAL ARTICLE
    Woodward G,

    Networking agroecology: integrating the diversity of agroecosystem interactions

    , Advance in Ecological Research
  • JOURNAL ARTICLE
    Balcombe P, Anderson K, Speirs J, Brandon N, Hawkes A, Balcombe P, Anderson K, Speirs J, Brandon N, Hawkes A, Balcombe P, Anderson K, Speirs J, Brandon N, Hawkes Aet al., 2017,

    The Natural Gas Supply Chain: The Importance of Methane and Carbon Dioxide Emissions

    , ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 5, Pages: 3-20, ISSN: 2168-0485

    Natural gas is typically considered to be the cleaner-burning fossil fuel that could play an important role within a restricted carbon budget. While natural gas emits less CO2 when burned than other fossil fuels, its main constituent is methane, which has a much stronger climate forcing impact than CO2 in the short term. Estimates of methane emissions in the natural gas supply chain have been the subject of much controversy, due to uncertainties associated with estimation methods, data quality, and assumptions used. This Perspective presents a comprehensive compilation of estimated CO2 and methane emissions across the global natural gas supply chain, with the aim of providing a balanced insight for academia, industry, and policy makers by summarizing the reported data, locating the areas of major uncertainty, and identifying where further work is needed to reduce or remove this uncertainty. Overall, the range of documented estimates of methane emissions across the supply chain is vast among an aggregation of different geological formations, technologies, plant age, gas composition, and regional regulation, not to mention differences in estimation methods. Estimates of combined methane and CO2 emissions ranged from 2 to 42 g CO2 eq/MJ HHV, while methane-only emissions ranged from 0.2% to 10% of produced methane. The methane emissions at the extraction stage are the most contentious issue, with limited data available but potentially large impacts associated with well completions for unconventional gas, liquids unloading, and also the transmission stage. From the range of literature estimates, a constrained range of emissions was estimated that reflects the most recent and reliable estimates: total supply chain GHG emissions were estimated to be between 3.6 and 42.4 g CO2 eq/MJ HHV, with a central estimate of 10.5. The presence of “super emitters”, a small number of facilities or equipment that cause extremely high emissions, is found across all supply chai

  • JOURNAL ARTICLE
    Baran D, Ashraf RS, Hanifi DA, Abdelsamie M, Gasparini N, Rohr JA, Holliday S, Wadsworth A, Lockett S, Neophytou M, Emmott CJM, Nelson J, Brabec CJ, Amassian A, Salleo A, Kirchartz T, Durrant JR, McCulloch I, Baran D, Ashraf RS, Hanifi DA, Abdelsamie M, Gasparini N, Röhr JA, Holliday S, Wadsworth A, Lockett S, Neophytou M, Emmott CJM, Nelson J, Brabec CJ, Amassian A, Salleo A, Kirchartz T, Durrant JR, McCulloch I, Baran D, Ashraf RS, Hanifi DA, Abdelsamie M, Gasparini N, Röhr JA, Holliday S, Wadsworth A, Lockett S, Neophytou M, Emmott CJM, Nelson J, Brabec CJ, Amassian A, Salleo A, Kirchartz T, Durrant JR, McCulloch I, Baran D, Ashraf RS, Hanifi DA, Abdelsamie M, Gasparini N, Röhr JA, Holliday S, Wadsworth A, Lockett S, Neophytou M, Emmott CJM, Nelson J, Brabec CJ, Amassian A, Salleo A, Kirchartz T, Durrant JR, McCulloch I, Baran D, Ashraf RS, Hanifi DA, Abdelsamie M, Gasparini N, Röhr JA, Holliday S, Wadsworth A, Lockett S, Neophytou M, Emmott CJM, Nelson J, Brabec CJ, Amassian A, Salleo A, Kirchartz T, Durrant JR, McCulloch I, Baran D, Ashraf RS, Hanifi DA, Abdelsamie M, Gasparini N, Röhr JA, Holliday S, Wadsworth A, Lockett S, Neophytou M, Emmott CJ, Nelson J, Brabec CJ, Amassian A, Salleo A, Kirchartz T, Durrant JR, McCulloch Iet al., 2017,

    Reducing the effciency-stability-cost gap of organic photovoltaics with highly effcient and stable small molecule acceptor ternary solar cells

    , NATURE MATERIALS, Vol: 16, Pages: 363-+, ISSN: 1476-1122

    Technological deployment of organic photovoltaic modules requires improvements in device light-conversion efficiency and stability while keeping material costs low. Here we demonstrate highly efficient and stable solar cells using a ternary approach, wherein two non-fullerene acceptors are combined with both a scalable and affordable donor polymer, poly(3-hexylthiophene) (P3HT), and a high-efficiency, low-bandgap polymer in a single-layer bulk-heterojunction device. The addition of a strongly absorbing small molecule acceptor into a P3HT-based non-fullerene blend increases the device efficiency up to 7.7 ± 0.1% without any solvent additives. The improvement is assigned to changes in microstructure that reduce charge recombination and increase the photovoltage, and to improved light harvesting across the visible region. The stability of P3HT-based devices in ambient conditions is also significantly improved relative to polymer:fullerene devices. Combined with a low-bandgap donor polymer (PBDTTT-EFT, also known as PCE10), the two mixed acceptors also lead to solar cells with 11.0 ± 0.4% efficiency and a high open-circuit voltage of 1.03 ± 0.01 V.

  • JOURNAL ARTICLE
    Bertei A, Tariq F, Yufit V, Ruiz-Trejo E, Brandon NP, Bertei A, Tariq F, Yufit V, Ruiz-Trejo E, Brandon NP, Bertei A, Tariq F, Yufit V, Ruiz Trejo E, Brandon Net al., 2017,

    Guidelines for the Rational Design and Engineering of 3D Manufactured Solid Oxide Fuel Cell Composite Electrodes

    , JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 164, Pages: F89-F98, ISSN: 0013-4651

    The growth of 3D printing has opened the scope for designing microstructures for solid oxide fuel cells(SOFCs) with improved power density and lifetime. This technique can introduce structural modifications at a scale larger than particle size but smaller than cell size, such as by insertingelectrolyte pillars of ~5-100 µm. This study sets the minimum requirements for the rational design of 3D printedelectrodes based on an electrochemical model and analytical solutions for functional layers with negligible electronic resistanceand no mixed conduction. Results show that this structural modification enhances the power density when the ratio keffbetween effective conductivity and bulk conductivity of the ionic phase is smaller than 0.5. The maximum performance improvement is predicted as a function of keff. A design study on a wide range of pillar shapes indicates that improvements are achieved by any structural modification which provides ionic conduction up to a characteristic thickness ~10-40 µm without removing active volume at the electrolyte interface. The best performance is reached for thin (< ~2 µm) and long (> ~80 µm) pillars when the compositeelectrode is optimised for maximum three-phase boundarydensity, pointing towards the design of scaffolds with well-defined geometry and fractal structures.

  • JOURNAL ARTICLE
    Bhave A, Taylor RHS, Fennell P, Livingston WR, Shah N, Mac Dowell N, Dennis J, Kraft M, Pourkashanian M, Insa M, Jones J, Burdett N, Bauen A, Beal C, Smallbone A, Akroyd J, Bhave A, Taylor RHS, Fennell P, Livingston WR, Shah N, Dowell NM, Dennis J, Kraft M, Pourkashanian M, Insa M, Jones J, Burdett N, Bauen A, Beal C, Smallbone A, Akroyd J, Bhave A, Taylor RHS, Fennell P, Livingston WR, Shah N, Dowell NM, Dennis J, Kraft M, Pourkashanian M, Insa M, Jones J, Burdett N, Bauen A, Beal C, Smallbone A, Akroyd J, Bhave A, Taylor RHS, Fennell P, Livingston WR, Shah N, Mac Dowell N, Dennis J, Kraft M, Pourkashanian M, Insa M, Jones J, Burdett N, Bauen A, Beal C, Smallbone A, Akroyd Jet al., 2017,

    Screening and techno-economic assessment of biomass-based power generation with CCS technologies to meet 2050 CO2 targets

    , APPLIED ENERGY, Vol: 190, Pages: 481-489, ISSN: 0306-2619

    © 2016 Elsevier Ltd Biomass-based power generation combined with CO 2 capture and storage (Biopower CCS) currently represents one of the few practical and economic means of removing large quantities of CO 2 from the atmosphere, and the only approach that involves the generation of electricity at the same time. We present the results of the Techno-Economic Study of Biomass to Power with CO 2 capture (TESBiC) project, that entailed desk-based review and analysis, process engineering, optimisation as well as primary data collection from some of the leading pilot demonstration plants. From the perspective of being able to deploy Biopower CCS by 2050, twenty-eight Biopower CCS technology combinations involving combustion or gasification of biomass (either dedicated or co-fired with coal) together with pre-, oxy- or post-combustion CO 2 capture were identified and assessed. In addition to the capital and operating costs, techno-economic characteristics such as electrical efficiencies (LHV% basis), Levelised Cost of Electricity (LCOE), costs of CO 2 captured and CO 2 avoided were modelled over time assuming technology improvements from today to 2050. Many of the Biopower CCS technologies gave relatively similar techno-economic results when analysed at the same scale, with the plant scale (MW e ) observed to be the principal driver of CAPEX (£/MW e ) and the cofiring % (i.e. the weighted feedstock cost) a key driver of LCOE. The data collected during the TESBiC project also highlighted the lack of financial incentives for generation of electricity with negative CO 2 emissions.

  • JOURNAL ARTICLE
    Biton M, Yufit V, Tariq F, Kishimoto M, Brandon N, Biton M, Yufit V, Tariq F, Kishimoto M, Brandon N, Biton M, Yufit V, Tariq F, Kishimoto M, Brandon NPet al., 2017,

    Enhanced Imaging of Lithium Ion Battery Electrode Materials

    , JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 164, Pages: A6032-A6038, ISSN: 0013-4651

    In this study we present a novel method of lithium ion battery electrode sample preparation with a new type of epoxy impregnation,brominated (Br) epoxy, which is introduced here for the first time for this purpose and found suitable for focused ion beam scanningelectron microscope (FIB-SEM) tomography. The Br epoxy improves image contrast, which enables higher FIB-SEM resolution (3Dimaging), which is amongst the highest ever reported for composite LFP cathodes using FIB-SEM. In turn it means that the particlesare well defined and the size distribution of each phase can be analyzed accurately from the complex 3D electrode microstructureusing advanced quantification algorithms.The authors present for the first time a new methodology of contrast enhancement for 3D imaging, including novel advancedquantification, on a commercial Lithium Iron Phosphate (LFP) LiFePO4 cathode. The aim of this work is to improve the quality ofthe 3D imaging of challenging battery materials by developing methods to increase contrast between otherwise previously poorlydifferentiated phases. This is necessary to enable capture of the real geometry of electrode microstructures, which allows measurementof a wide range of microstructural properties such as pore/particle size distributions, surface area, tortuosity and porosity. Theseproperties play vital roles in determining the performance of battery electrodes.

  • JOURNAL ARTICLE
    Bridgestock L, Rehkamper M, van de Flierdt T, Murphy K, Khondoker R, Baker AR, Chance R, Strekopytov S, Humphreys-Williams E, Achterberg EP, Bridgestock L, Rehkämper M, van de Flierdt T, Murphy K, Khondoker R, Baker AR, Chance R, Strekopytov S, Humphreys-Williams E, Achterberg EP, Bridgestock L, Rehkämper M, van de Flierdt T, Murphy K, Khondoker R, Baker AR, Chance R, Strekopytov S, Humphreys-Williams E, Achterberg EP, Bridgestock L, Rehkamper M, van de Flierdt T, Murphy K, Khondoker R, Baker AR, Chance R, Strekopytov S, Humphreys-Williams E, Achterberg EPet al., 2017,

    The Cd isotope composition of atmospheric aerosols from the Tropical Atlantic Ocean

    , GEOPHYSICAL RESEARCH LETTERS, Vol: 44, Pages: 2932-2940, ISSN: 0094-8276

    ©2017. The Authors. Stable isotope compositions can potentially be used to trace atmospheric Cd inputs to the surface ocean and anthropogenic Cd emissions to the atmosphere. Both of these applications may provide valuable insights into the effects of anthropogenic activities on the cycling of Cd in the environment. However, a lack of constraints for the Cd isotope compositions of atmospheric aerosols is currently hindering such studies. Here we present stable Cd isotope data for aerosols collected over the Tropical Atlantic Ocean. The samples feature variable proportions of mineral dust-derived and anthropogenic Cd, yet exhibit similar isotope compositions, thus negating the distinction of these Cd sources by using isotopic signatures in this region. Isotopic variability between these two atmospheric Cd sources may be identified in other areas, and thus warrants further investigation. Regardless, these data provide important initial constraints on the isotope composition of atmospheric Cd inputs to the ocean.

  • JOURNAL ARTICLE
    Chakrabarti B, Nir D, Yufit V, Tariq F, Rubio-Garcia J, Maher R, Kucernak A, Aravind PV, Brandon N, Chakrabarti B, Nir D, Yufit V, Tariq F, Rubio-Garcia J, Maher R, Kucernak A, Aravind PV, Brandon N, Chakrabarti B, Nir D, Yufit V, Tariq F, Rubio-Garcia J, Maher R, Kucernak A, Aravind PV, Brandon N, Chakrabarti BK, Nir DP, Yufit V, Tariq F, Rubio Garcia J, Maher R, Kucernak A, Aravind PV, Brandon NPet al., 2017,

    Performance Enhancement of Reduced Graphene Oxide-Modified Carbon Electrodes for Vanadium Redox-Flow Systems

    , CHEMELECTROCHEM, Vol: 4, Pages: 194-200, ISSN: 2196-0216

    © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. Reduced graphene oxide (rGO) suspended in an N,N′-dimethylformamide (DMF) solvent underwent electrophoretic deposition (EPD) on carbon paper (CP) electrodes. X-ray computed micro-tomography (XMT) indicates a 24 % increase in the specific surface area of CP modified with rGO in comparison to the untreated sample. Furthermore, XMT confirms that the deposition also penetrates into the substrate. Raman analysis shows that the rGO deposited is more amorphous than the CP electrode. A significant reduction in charge-transfer resistance of the VO 2 + /VO 2+ reaction is also observed (from impedance measurements) in modified samples in comparison to untreated CP electrodes.

  • JOURNAL ARTICLE
    Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li XD, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DC, Graham NJ, Ok YS, Feng Y, Li XDet al., 2017,

    Insights into the subsurface transport of As(V) and Se(VI) in produced water from hydraulic fracturing using soil samples from Qingshankou Formation, Songliao Basin, China

    , ENVIRONMENTAL POLLUTION, Vol: 223, Pages: 449-456, ISSN: 0269-7491

    Produced water is a type of wastewater generated from hydraulic fracturing, which may pose a risk to the environment and humans due to its high ionic strength and the presence of elevated concentrations of metals/metalloids that exceed maximum contamination levels. The mobilization of As(V) and Se(VI) in produced water and selected soils from Qingshankou Formation in the Songliao Basin in China were investigated using column experiments and synthetic produced water whose quality was representative of waters arising at different times after well creation. Temporal effects of produced water on metal/metalloid transport and sorption/desorption were investigated by using HYDRUS-1D transport modelling. Rapid breakthrough and long tailings of As(V) and Se(VI) transport were observed in Day 1 and Day 14 solutions, but were reduced in Day 90 solution probably due to the elevated ionic strength. The influence of produced water on the hydrogeological conditions (i.e., change between equilibrium and non-equilibrium transport) was evidenced by the change of tracer breakthrough curves before and after the leaching of produced water. This possibly resulted from the sorption of polyacrylamide (PAM (-CH2CHCONH2-)n) onto soil surfaces, through its use as a friction reducer in fracturing solutions. The sorption was found to be reversible in this study. Minimal amounts of sorbed As(V) were desorbed whereas the majority of sorbed Se(VI) was readily leached out, to an extent which varied with the composition of the produced water. These results showed that the mobilization of As(V) and Se(VI) in soil largely depended on the solution pH and ionic strength. Understanding the differences in metal/metalloid transport in produced water is important for proper risk management.

  • JOURNAL ARTICLE
    Chen SS, Suna Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li XD, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DCW, Graham NJD, Ok YS, Feng Y, Li X-D, Chen SS, Sun Y, Tsang DC, Graham NJ, Ok YS, Feng Y, Li XDet al., 2017,

    Potential impact of flowback water from hydraulic fracturing on agricultural soil quality: Metal/metalloid bioaccessibility, Microtox bioassay, and enzyme activities

    , SCIENCE OF THE TOTAL ENVIRONMENT, Vol: 579, Pages: 1419-1426, ISSN: 0048-9697

    Hydraulic fracturing has advanced the development of shale gas extraction, while inadvertent spills of flowback water may pose a risk to the surrounding environment due to its high salt content, metals/metalloids (As, Se, Fe and Sr), and organic additives. This study investigated the potential impact of flowback water on four representative soils from shale gas regions in Northeast China using synthetic flowback solutions. The compositions of the solutions were representative of flowback water arising at different stages after fracturing well establishment. The effects of solution composition of flowback water on soil ecosystem were assessed in terms of metal mobility and bioaccessibility, as well as biological endpoints using Microtox bioassay (Vibrio fischeri) and enzyme activity tests. After one-month artificial aging of the soils with various flowback solutions, the mobility and bioaccessibility of As(V) and Se(VI) decreased as the ionic strength of the flowback solutions increased. The results inferred a stronger binding affinity of As(V) and Se(VI) with the soils. Nevertheless, the soil toxicity to Vibrio fischeri only presented a moderate increase after aging, while dehydrogenase and phosphomonoesterase activities were significantly suppressed with increasing ionic strength of flowback solutions. On the contrary, polyacrylamide in the flowback solutions led to higher dehydrogenase activity. These results indicated that soil enzyme activities were sensitive to the composition of flowback solutions. A preliminary human health risk assessment related to As(V) suggested a low level of cancer risk through exposure via ingestion, while holistic assessment of environmental implications is required.

  • JOURNAL ARTICLE
    Chen Z, Wang X, Brandon N, Atkinson A, Chen Z, Wang X, Brandon N, Atkinson A, Chen Z, Wang X, Brandon N, Atkinson Aet al., 2017,

    Analysis of spherical indentation of porous ceramic films

    , JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 37, Pages: 1031-1038, ISSN: 0955-2219

    Spherical indentation of a porous brittle La0.6Sr0.4Co0.2Fe0.8O3 ceramic film (porosity=39.7%) on a stiffer elastic Ce0.9Gd0.1O1.95 substrate is simulated by finite element modelling incorporating the Gurson model to account for densification. The simulated load-displacement curves, apparent elastic modulus E, indentation hardness H and densification profile are all in good agreement with experimental data for the film. The simulations show that E and H are not sensitive to film residual stress. However E is very sensitive to the indent depth-film thickness ratio f, although H is less so for f<0.3. The simulated dependence of E and H on f are highly consistent with experimental data, supporting the extrapolation of E and H measured for 0.1<f<0.3, to zero depth for good estimates of the film-alone properties. The inclusion of densification in the simulation makes only a small difference to E, but has a large influence on H as a function of indentation depth.

  • JOURNAL ARTICLE
    Cheng C, Yan L, Mirchi A, Madani K, Chuntian C, Yan L, Mirchi A, Madani K, Cheng C, Yan L, Mirchi A, Madani K, Cheng C, Yan L, Mirchi A, Madani Ket al., 2017,

    China's Booming Hydropower: Systems Modeling Challenges and Opportunities

    , JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT, Vol: 143, Pages: 02516002-02516002, ISSN: 0733-9496

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