Centre for Marine and Renewable Energy (MaREI) - Journal Articles

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    Enhancing microbial superoxide generation and conversion to hydroxyl radicals for enhanced bioremediation using iron-binding ligands
    (Elsevier B.V., 2024-02-01) Wang, Yuhan; Ning, Xue; Liang, Jinsong; Wang, Aijie; Qu, Jiuhui; National Natural Science Foundation of China; Shenzhen Science and Technology Innovation Program
    Harnessing bacteria for superoxide production in bioremediation holds immense promise, yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide. This study delves into a cost-effective approach to amplify superoxide production using an Arthrobacter strain, a prevalent soil bacterial genus. Our research reveals that introducing a carbon source along with specific iron-binding ligands, including deferoxamine (DFO), diethylenetriamine pentaacetate (DTPA), citrate, and oxalate, robustly augments microbial superoxide generation. Moreover, our findings suggest that these iron-binding ligands play a pivotal role in converting superoxide into hydroxyl radicals by modulating the electron transfer rate between Fe(III)/Fe(II) and superoxide. Remarkably, among the tested ligands, only DTPA emerges as a potent promoter of this conversion process when complexed with Fe(III). We identify an optimal Fe(III) to DTPA ratio of approximately 1:1 for enhancing hydroxyl radical production within the Arthrobacter culture. This research underscores the efficacy of simultaneously introducing carbon sources and DTPA in facilitating superoxide production and its subsequent conversion to hydroxyl radicals, significantly elevating bioremediation performance. Furthermore, our study reveals that DTPA augments superoxide production in cultures of diverse soils, with various soil microorganisms beyond Arthrobacter identified as contributors to superoxide generation. This emphasizes the universal applicability of DTPA across multiple bacterial genera. In conclusion, our study introduces a promising methodology for enhancing microbial superoxide production and its conversion into hydroxyl radicals. These findings hold substantial implications for the deployment of microbial reactive oxygen species in bioremediation, offering innovative solutions for addressing environmental contamination challenges.
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    Energy management strategy of a green port serving emission-free ferries considering EV parking lot availability
    (Institute of Electrical and Electronics Engineers (IEEE), 2023-12-20) Ozdemir, Hilal; Güldorum, Hilmi Cihan; Erenoğlu, Ayşe Kübra; Sengor, Ibrahim; Hayes, Barry P.; Erdinç, Ozan; Science Foundation Ireland; Junta de Comunidades de Castilla-La Mancha; European Regional Development Fund; Universidad de Castilla-La Mancha
    While the role of transportation is indispensable in daily life, the transportation sector is one of the major contributors to greenhouse gas (GHG) emissions. With the utilization of green vehicles in transportation systems and the adoption of renewable energy sources in power systems, it becomes possible to achieve an environmentally friendly transportation system. In this paper, an energy management algorithm for a port power system is presented, including a solar-based local power production unit serving hybrid ferries having fuel cell/battery, as well as an electric vehicle (EV) parking lot, allowing for bi-directional power flow between the port and the grid. The proposed concept enables dual integrated green transportation with the possibility of parking EVs to the lot and then continuing to journey via another green transportation option. The stochasticity regarding the photovoltaic plant (PVP) and EV behaviors are taken into consideration under a real-time rolling horizon optimization framework. Minimizing the operational cost of the port related to the energy consumption is the objective function in this novel transportation-to-transportation integration concept. Numerous case studies have been developed and tested to demonstrate the effectiveness of the suggested algorithm.
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    Tidal stream energy potential in the Shannon Estuary
    (Elsevier Ltd., 2021-12-18) Fouz, D. M.; Carballo, R.; López, I.; Iglesias, Gregorio; European Regional Development Fund; Xunta de Galicia
    The tidal and river in-stream energy resource in the Shannon Estuary (W Ireland) is investigated using of high-resolution numerical modelling and spatial analysis. Although freshwater discharges are large, their influence on the available resource is found to be all but negligible, the tide being the main driver of estuarine circulation. The Tidal Stream Exploitability (TSE) index is adapted to the analysis of estuaries with non-depth-limited areas (TSEndl), such as the Shannon Estuary, and then used to select the hotspots with potential for a tidal stream farm. For this purpose, a new depth penalty-limiting function is defined to avoid overestimating the available energy potential in areas with depths greater than those required for tidal energy converter operation. Seven hotspots are identified based on the revised index. The approach followed in this study illustrates the applicability of high-resolution numerical modelling and spatial analysis for identifying the most appropriate areas for tidal stream energy conversion. Finally, the potential of tidal stream energy to contribute to the much-needed decarbonisation of the energy mix in Ireland is emphasized.
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    A holistic methodology for hydrokinetic energy site selection
    (Elsevier Ltd., 2022-04-25) Fouz, D. M.; Carballo, R.; López, I.; Iglesias, Gregorio; European Regional Development Fund; Xunta de Galicia
    Hydrokinetic energy can contribute to diversify and decarbonise the energy mix in many coastal regions, in particular estuaries. These are typically areas of high environmental value and with intense socioeconomic activity. The aim of this work is to provide a comprehensive methodology for selecting the optimum locations for hydrokinetic energy exploitation, by considering all the relevant aspects which affect the decision-making process, and improve the current available procedures. The methodology is centred around a novel holistic index, the Integrated Hydrokinetic Energy (IHE) index, which considers: (i) the exploitable resource, (ii) the costs of installation, and (iii) the socioeconomic and environmental aspects. The approach is illustrated through a case study in the Shannon Estuary, on the west coast of Ireland. It is shown that the application of this methodology facilitates the planning and reduces the uncertainties in the development of a hydrokinetic farm project.
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    Electrofuels in a circular economy: A systems approach towards net zero
    (Elsevier Ltd., 2023-07-05) Rusmanis, Davis; Yang, Yan; Long, Aoife; Gray, Nathan; Martins, Kelvin C.; Ó Loideáin, Seán Óg; Lin, Richen; Kang, Xihui; Cusack, Donal Óg; Carton, James G.; Monaghan, Rory; Murphy, Jerry D.; Wall, David M.; Science Foundation Ireland
    Decarbonising the hard-to-abate sectors will be necessary in realising a future net-zero economy. Electrofuels store electricity as low carbon energy vectors such as hydrogen or methane which can be used in areas where electrification is not ideal, and as such can facilitate decarbonisation of sectors such as transport, agriculture, and wastewater treatment. In this study, the production of electrofuels was analysed at an industrial site by storing renewable electricity as green hydrogen produced using electrolysis. The analysis highlighted the need for scale in hydrogen production. The cost of hydrogen was calculated at €8.92/kg when a 122 kW electrolyser operated solely on curtailed electricity generated from the industry site was situated at a 65,000 person equivalent municipal wastewater treatment plant. A subsequent integrated and circular approach to electrofuels production was investigated. The oxygen by-product from electrolysis could be utilised for wastewater aeration and reduce the annual electricity usage at the wastewater treatment plant by 3.6%. Furthermore, the carbon dioxide in biogas generated from sewage sludge could be converted to methane through a Sabatier reaction (4H2 + CO2 → CH4 + 2H2O) as a means of carbon capture and utilisation. The hydrogen produced from the 122 kW electrolyser could convert only 40% of the total carbon dioxide (within the biogas) in a biomethanation process, again supporting the argument for larger electrolyser systems with increased hydrogen production. Pyrolysis of digestate to produce biochar was investigated as a negative emissions technology. If pyrolysis is coupled with anaerobic digestion of feedstocks within 10 km of the industry site savings of 42.7 kt CO2/a could be achieved. In essence, a circular economy approach to electrofuel production could integrate existing electrical, gas and water infrastructure, whilst treating waste, improving the environment, decarbonising agriculture, and storing energy in the form of new low carbon energy vectors for use in heavy transport. Such an approach is vital to progressing future net-zero strategies, however future emissions accountancy processes must adapt to facilitate the benefits of a circular economy.