Civil and Environmental Engineering - Journal articles

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Geotechnical and geoenvironmental engineering education during the pandemic
(ICE Publishing, 2021-05-07) Jiang, Ning-Jun; Hanson, James L.; Della Vecchia, Gabriele; Zhu, Cheng; Yi, Yaolin; Arnepalli, Dali N.; Courcelles, Benoit; He, Jia; Horpibulsuk, Suksun; Hoy, Menglim; Takahashi, Akihiro; Arulrajah, Arul; Lin, Chih-Ping; Dowoud, Osama; Li, Zili; Gao, Zhiwei; Hata, Toshiro; Zhang, Limin; Du, Yan-Jun; Goli, Venkata Siva Naga Sai; Mohammad, Arif; Singh, Prithvendra; Kuntikana, Ganaraj; Singh, Devendra N.
This paper reports the impact of coronavirus disease 2019 on the practice and delivery of geotechnical and geoenvironmental engineering (GGE) education modules, including lectures, lab sessions, student assessments and research activities, based on the feedback from faculty members in 14 countries/regions around the world. Faculty members have since adopted a series of contingent measures to enhance teaching and learning experience during the pandemic, which includes facilitating active learning, exploring new teaching content related to public health, expanding e-learning resources, implementing more engaged and student-centred assessment and delivering high-impact integrated education and research. The key challenges that faculty members are facing appear to be how to maximise the flexibility of learning and meet physical distancing requirements without compromising learning outcomes, education equity and interpersonal interactions in the traditional face-to-face teaching. Despite the challenges imposed by the pandemic, this could also be a good opportunity for faculty members obliged to lecture, to rethink and revise the existing contents and approaches of professing GGE education. Three future opportunities namely, smart learning, flipped learning and interdisciplinary education, are identified. The changes could potentially provide students with a more resilient, engaged, interactive and technology-based learning environment.
Dedicated large-scale floating offshore wind to hydrogen: Assessing design variables in proposed typologies
(Elsevier B.V., 2022-03-01) Ibrahim, Omar S.; Singlitico, Alessandro; Proskovics, Roberts; McDonagh, Shane; Desmond, Cian; Murphy, Jerry D.; Horizon 2020; Science Foundation Ireland
To achieve the Net-Zero Emissions goal by 2050, a major upscale in green hydrogen needs to be achieved; this will also facilitate use of renewable electricity as a source of decarbonised fuel in hard-to-abate sectors such as industry and transport. Nearly 80% of the world's offshore wind resource is in waters deeper than 60 m, where bottom-fixed wind turbines are not feasible. This creates a significant opportunity to couple the high capacity factor floating offshore wind and green hydrogen. In this paper we consider dedicated large-scale floating offshore wind farms for hydrogen production with three coupling typologies; (i) centralised onshore electrolysis, (ii) decentralised offshore electrolysis, and (iii) centralised offshore electrolysis. The typology design is based on variables including for: electrolyser technology; floating wind platform; and energy transmission vector (electrical power or offshore hydrogen pipelines). Offshore hydrogen pipelines are assessed as economical for large and distant farms. The decentralised offshore typology, employing a semi-submersible platform could accommodate a proton exchange membrane electrolyser on deck; this would negate the need for an additional separate structure or hydrogen export compression and enhance dynamic operational ability. It is flexible; if one electrolyser (or turbine) fails, hydrogen production can easily continue on the other turbines. It also facilities flexibility in further expansion as it is very much a modular system. Alternatively, less complexity is associated with the centralised offshore typology, which may employ the electrolysis facility on a separate offshore platform and be associated with a farm of spar-buoy platforms in significant water depth locations.
Shear behaviour of peat at different stress levels
(Institution of Civil Engineers, 2023-01-03) Wang, Di; Li, Zili; Irish Centre for Research in Applied Geosciences; Science Foundation Ireland; University College Cork; Hebei University of Technology
In this study, a series of consolidated, undrained triaxial compression tests were conducted to investigate peat shear behaviour on samples from 1.65 m depth when subjected to different stress levels from 10.4 kPa to 40.5 kPa. At the consolidation stage, the triaxial test specifically investigated the peat isotropic compressibility at low stress levels, showing an agreement with oedometer test data available in literature. The subsequent triaxial shearing stage results show most of the test data failed to reach the tension cut-off line (q/p’ = 3), which indicated that the deviator stress may represent more of an interparticle connection than the tension of fibres and woods in peaty soils. For peat, the membrane correction effect on peat shear resistance is strain dependent; generally, small within 10% shear strain, but becomes significant above 10% shear strain. A critical state line for peat was determined based on the maximum curvature approach, where the Mohr-Coulomb model has difficulty in determining the friction angle for peat. Of the data recorded for the peat, 78% fell within the range of 30 to 60 degrees, increasing to 90.4% when ignoring points lower than 10 kPa; the previous test data for very low stress level (less than 10kPa) might not be sufficiently reliable due to limitations of conventional triaxial testing apparatus, specimen preparation and etc. In addition, organic content also plays an important role on the peat shear behaviour. In general, when the organic content exceeds 75%, the deviator stress behaves like organic soils, otherwise, the peat behaves more like a mineral soil. In peat samples with organic content higher than 75%, the direct shear box test gives higher estimates of shear strength than the triaxial shear test, but not necessarily accurate — the mechanism of direct shear acts only at the centre of a specimen, while triaxial shear can shear throughout the specimens.
Improvement in biohydrogen and volatile fatty acid production from seaweed through addition of conductive carbon materials depends on the properties of the conductive materials
(Elsevier, 2022-01) Deng, Chen; Lin, Richen; Kang, Xihui; Wu, Benteng; Wall, David M.; Murphy, Jerry D.; Science Foundation Ireland; European Regional Development Fund; Environmental Protection Agency; Sustainable Energy Authority of Ireland; Gas Networks Ireland
Fermentative production of biohydrogen and volatile fatty acids (VFAs) from advanced feedstocks such as seaweed provides opportunities in the carbon-neutral bioeconomy. The gap in the state of the art exists in overcoming both the low fermentation efficiency associated with the rigid structure of seaweed and the inefficient metabolic electron transfer within the microbial communities. This study evaluated the effects of carbonaceous additives (such as graphene and various biochars) on biohydrogen fermentation of glucose, cellulose, and the brown seaweed Laminaria digitata. The impacts of carbonaceous additives varied significantly in terms of hydrogen production, VFA profiles, and microbial communities. Graphene and wood-derived biochar (Wood_Biochar) were shown to be superior to draff-derived biochars. In the fermentation of L. digitata, graphene and Wood_Biochar significantly reduced the lag-phase time by 47% and 49%, respectively. Microbial analysis revealed that the enhanced fermentation was ascribed to the enrichment of Thermoanaerobacterium genus in response to carbonaceous additives. Kinetic correlations between the fermentation parameters and the properties of the additives suggested that the graphitic structure and electrical conductivity might play a crucial role in facilitating the fermentation. The mechanisms might be ascribed to (1) the supported biofilm growth and (2) enhancement in microbial electron transfer induced by the additives.
Improved robustness of ex-situ biological methanation for electro-fuel production through the addition of graphene
(Elsevier, 2021-12) Wu, Benteng; Lin, Richen; Kang, Xihui; Deng, Chen; Dobson, Alan D. W.; Murphy, Jerry D.; Environmental Protection Agency; Science Foundation Ireland; Sustainable Energy Authority of Ireland; Department of the Environment, Climate and Communications
Ex-situ biomethanation (CO2 + 4H(2)-> CH4 + 2H(2)O) can simultaneously achieve renewable electricity storage and CO2 valorisation. However, fluctuations in variable renewable electricity may lead to intermittent hydrogen supply, which is shown to adversely affect microbial activity and performance of the biomethanation process. Carbonaceous materials may act as an abiotic additive to enhance microbial robustness and improve system performance. Nanomaterial graphene and pyrochar were compared to assess their effects on biomethanation systems with an intermittent supply of hydrogen. Results revealed that intermittent gas supply caused deterioration in the restart performance with only 66% of theoretical methane production obtained in the control compared with 84% under steady state conditions. The addition of graphene in biomethanation led to 78% of the theoretical methane production after repetitive intermittent supply; this improvement is postulated to be due to its high electrical conductivity and large specific surface (500 m(2)/g). In comparison, pyrochar amendment did not lead to a significant improvement in upgrading performance. Microbial analysis showed that the OTUs affiliated to bacteria withinin the order SHA-98 (42.9% in abundance) and archaea from the genus Methanothermobacter (99%) may result in the establishment of a new syntrophic relationship to improve the robustness of biomethanation process.

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