Environmental Research Institute - Doctoral Theses

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    A multi-method approach to understanding the ecology of harbour porpoise in Irish waters
    (University College Cork, 2023) Todd, Nicole R. E.; Jessopp, Mark John; Rogan, Emer; Kavanagh, Ailbhe; Irish Research Council
    Small coastal cetaceans are often some of the most threatened species by anthropogenic and climate change impacts. Distribution and behavioural patterns can be difficult to determine for these wide-ranging, cryptic species that spend a limited amount of time at the surface, making direct observation difficult. Harbour porpoise (Phocoena phocoena phocoena, Linnaeus, 1758) is protected across European waters, listed under Annex II of the EU Habitats Directive, requiring Special Areas of Conservation (SAC) for their conservation. Despite its protected status, harbour porpoise are a relatively understudied species. It is therefore important to determine long-term habitat use patterns to ensure effective conservation is put in place. This research uses long-term passive acoustic monitoring (PAM) to increase our understanding of harbour porpoise habitat use in Irish waters. Firstly, feeding buzzes and spatial-orientation echolocation clicks of harbour porpoise were differentiated within a 9-year PAM dataset from northwest Ireland (Chapter 2). The spatio-temporal distribution of foraging behaviour was investigated using Generalized Additive Models (GAMs), at multiple temporal scales. The research identified clear interannual and seasonal variation, with peak foraging buzzes detected in autumn, as well as highlighting a negative impact of construction related activities in the area. A new PAM monitoring network was also established in an SAC designated for harbour porpoise in southwest Ireland, over a 3-year period. GAMs were used to examine harbour porpoise occurrence and foraging behaviour in relation to intra-site differences in habitat use and environmental variables (Chapter 5). Harbour porpoise were detected year-round within the SAC, with seasonal trends in occurrence and foraging behaviour observed, with peak detections in the late autumn and winter reflecting similar trends from Broadhaven Bay (Chapter 2). Clear preferences in habitat use were identified, with porpoise occurrence and foraging varying across small spatial scales, as well as across diel, tidal, and lunar cycles. This research also noted an overall decline in acoustic detections across the monitoring period, reflecting wider population trends in Irish waters that bears further investigation. An in-field comparison of a widely used PAM tool, the C-POD (Cetacean POrpoise Detector) with its recently developed successor the F-POD (Full waveform capture POD) was conducted, providing timely insights into the integration of this new equipment into acoustic monitoring programmes (Chapter 3). The F-POD recorded twice the amount of harbour porpoise detections compared to a co-deployed C-POD. GAMs highlighted similar patterns of harbour porpoise occurrence, however, in contrast to the F-POD, the C-POD failed to detect sufficient foraging rates to identify temporal trends in foraging behaviour. This work suggests that the switch to F-PODs will likely have minimal effect on our understanding of seasonal patterns of occurrence but may improve our understanding of foraging. Following on from this finding, an in-field playback experiment was conducted to determine the detection probability and effective detection radius/area (EDR/EDA) of three commonly used PAM devices, the C-POD, the F-POD, along with a continuous recording hydrophone (SoundTrap) (Chapter 4). The SoundTrap detected porpoise playbacks at the greatest distance, followed by the F-POD. The C-POD detection range was considerably less than the other two PAM devices. The type of harbour porpoise echolocation (spatial orientation clicks versus buzzes) was also found to influence the detection range, with clicks detected at a closer range across all devices. Understanding how this range of PAM devices compare provides valuable information to enable robust comparison of studies and inform appropriate planning of acoustic monitoring programmes. Collectively, the research has significantly enhanced our knowledge of acoustic monitoring methodologies and identified key harbour porpoise habitat use patterns. The findings can inform more effective conservation management of harbour porpoise at a national and international level. Additionally, this research contributes valuable insights to inform the designation of protected areas to cover important feeding habitats, and ensure targeted protections are put in place in the future.
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    GIS techno-economic tool development and application for wave and tidal energy
    (University College Cork, 2023) O'Connell, Ross; Murphy, Jimmy; Devoy McAuliffe, Fiona; European Regional Development Fund
    The ocean energy sector is progressing towards commercialisation, with wave and tidal energy demonstration projects now being deployed across the globe. Well informed site selection and project feasibility analysis for commercial farms will be reliant on high-quality geospatial data and techno-economic tools/models respectively. The research undertaken for this doctoral thesis involved the modelling of new geospatial data which will be critical to future site suitability analyses for ocean energy farms in Ireland and the UK. This included new high-resolution geodata on the ocean energy resources, met-ocean characteristics, farm accessibility, device availability and energy production based on real wave and tidal energy devices. Other relevant criteria mapped as part of the research included proximity to port and grid access, bathymetry, seabed character, marine traffic and fishing activity. A fully open-access Web-GIS tool has been developed to host this data and includes functionality enabling the user to perform interactive site suitability and project feasibility analysis through the integration of a built-in site selection aid and techno-economic calculator, the latter of which couples geodata with techno-economic data to facilitate the calculation of project feasibility estimates. Site selection case studies performed using this geodata in conjunction with ocean energy technology developer input have revealed vast areas, primarily in the west of the study area, suitable for wave energy deployment and less extensive areas, primarily in the east of the study area, suitable for tidal energy deployment, varying somewhat depending on technology type. Advanced geospatial modelling of the levelized cost of energy for wave energy in the region has also been performed, revealing the areas likely to achieve the best return on investment for future commercial scale deployment in the region. A detailed site-specific project feasibility case study using the techno-economic calculator demonstrated its application for tidal energy.
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    Field measurements and atmospheric simulation chamber studies of selected biomass burning marker compounds
    (University College Cork, 2023) O'Sullivan, Niall Patrick; Wenger, John; Environmental Protection Agency; Irish Research Council
    Biomass burning is a key contributor to ambient air pollution, which has significant impacts on climate and health. Biomass burning emits both solid particles and gaseous species known as volatile organic compounds (VOCs) which can undergo chemical oxidation reactions in the atmosphere with hydroxyl (OH) and nitrate (NO3) radicals to produce secondary organic aerosols (SOA). While the particulate pollution has been well characterised, information on the VOCs associated with biomass burning is limited. To this end, a Time-of-Flight Chemical Ionisation Mass Spectrometer (ToF-CIMS) was deployed in Cork City, for the first comprehensive field study on the VOCs associated with residential burning of solid fuels (wood, peat, coal) in Ireland. In the field study, a range of phenols and their nitro derivatives were detected during air pollution events caused by residential solid fuel burning. By following the evolution of these biomass burning markers through the night, evidence was found for the atmospheric conversion of phenol compounds to their analogous nitrophenols via gas-phase reaction with NO 3 . Positive matrix factorisation was used to identify six different source categories for the VOCs which included fresh and atmospherically processed emissions from solid fuel burning, as well as oxidized emissions from local and regional background sources such as vehicles and agriculture. A series of simulation chamber studies was also performed on the OH-initiated oxidation of two biomass burning marker compounds, 4-methylcatechol and guaiacol. The ToF-CIMS identified a large range of gas and particle products including polyphenols, nitrophenols, benzoquinones, ring scission species and accretion products, generating new information on the atmospheric degradation pathways. The results confirm the importance of both OH addition and H-atom abstraction reactions in initiating the oxidation processes and interestingly, in the case of guaiacol, loss of the methoxy group to form catechol which also underwent similar degradation pathways. A wide range of highly oxidized and nitro-containing species were identified in the particle phase which experienced further chemical processing, thus providing new insights into the mechanisms for the formation and atmospheric aging of SOA produced from biomass burning.
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    Electrofuels in a circular economy
    (University College Cork, 2023) Rusmanis, Davis; Murphy, Jerry; Wall, David; Science Foundation Ireland
    With the global shift away from traditional dispatchable fossil hydrocarbon fuels, the requirement for energy storage is of increasing importance. Renewable electricity generation is predominately in the form of variable renewable electricity, produced by wind and solar technologies. Intermittent production of electricity leads to an inevitable mismatch in supply and demand between the grid and the consumers. This can lead to periods of surplus power generation – and subsequent dispatch down – during low demand; conversely it can also lead to energy shortages during periods when there is insufficient power generation to match high demand which can lead to grid blackouts. Due to the difficulty in storing significant quantities of electricity via the grid, or batteries, sustainable alternative methods of energy storage must be devised. In recent years, electrofuels have become a centre-stage topic due to the opportunity to store electricity as low-carbon energy vectors which can be utilised where electrification may not be ideal, such as the hard-to-abate sectors of haulage, shipping, agriculture, and industry (iron, steel and chemicals). Further, the generation of these electrofuels could be carried out using electricity which would otherwise be lost, during times of excess production, and low grid demand. Combining technologies such as electrolysers (capable of producing hydrogen and oxygen) and biomethanation (which can combine carbon dioxide with hydrogen to form biomethane), offer a green alternative to fossil natural gas, and can use the existing gas grid as both a distribution system and a sustainable energy storage method. Based on the literature review and previous research, the initial thesis work focused on the design and commission of a prototype three-phase cascading biomethanation system. The fabricated prototype used diffusers as the agitation method and was deemed to be at a technology readiness level (TRL) of 4. The system was designed based on the results of a previously simulated system published by this research group (Voelklein et al., 2019); the results from this study were of similar performance to the previous model. The commissioning process produced carbon conversion rates between 72% and 97% across 3 reactors which can operate in parallel or series. A methane evolution rate of 2.9 L CH4/LVR/d was achieved at medium flow rates. Increasing the flow rates resulted in substantial drops in the conversion efficiency of the system. This limitation was mooted as likely due to the low bubble column height of the system. The design of the system was limited by the dimensions of the system, which were associated with health and safety concerns of the University. Assessing the integration of biomethanation technology into the wider energy, and environment sector, an initial small-scale case study of a circular economy system was carried out, based on local industry. Using a dataset from two local wind turbines to assess available surplus electricity, a small 122 kW electrolyser was proposed to be of a suitable size for the local site. This electrolyser would generate enough by-product oxygen to supply 8.9% of the oxygen demand of the aeration process for the local wastewater treatment plant of approximately 65,000 population equivalent. The product hydrogen could be used directly as a transport fuel, or convert 40% of the CO2 generated by the anaerobic digesters at the wastewater treatment plant into biomethane. This system could reduce the wastewater treatment plant emissions by 3.6% due to the reduced aeration requirement (pumping oxygen instead of air would reduce electricity usage). Should an appropriately sized electrolyser be used, up to a 40% reduction in emissions and energy use could be achieved. However, the small scale of the system was identified as a major barrier to the application of the technology, with the levelised cost of hydrogen evaluated at €8.92/kg H2 (or 27c/kWh). This resulting high cost cannot justify the implementation of a small-scale system to capture intermittent curtailed electricity as initially proposed. Expanding the circular economy system is possible with a carbon-negative emission pathway integrating pyrolysis technology to generate biochar. Anaerobic digesters and pyrolysis systems could potentially reduce greenhouse gas emissions by 42.7 kt CO2 through biomethane production from substrates within a 10km radius and through biochar production from digestate. When considering the sustainability considerations set by the latest version of the EU Renewable Energy Directive, electrofuels may only be certified as a renewable energy supply by affecting a 70% emission saving when compared to the current fossil hydrocarbon fuels. Additionally, the Directive does not allow for emission saving associated with carbon capture and reuse within the biological methanation system despite the added capture and use of otherwise curtailed electricity. Assessing a large-scale circular economy system, once again co-locating electrolysers with anaerobic digesters and biomethanation systems on new or existing large wastewater treatment plants can offer significant benefits. To supply a 10 MW electrolyser operating at an 80% operating capacity, a wind farm of 144MW size (18 x 8 MW turbines) operating at 57 % capacity would be necessary, with an assumed 10% curtailment scenario, reflective of the Irish grid dispatch down of the recent years. The 10 MW electrolyser could supply oxygen for a wastewater treatment plant of 426,000 population equivalent, reducing the plant emissions (and power demand) by 40% when compared to traditional gaseous air aeration. The produced wastewater sludge can be digested to produce biogas. The CO2 component of biogas can be converted to methane using a biomethanation system, requiring 22% of the electrolyser-produced hydrogen. This would result in the capture of 16 ktCO2e per annum while producing enough electrofuels to offset 390 diesel trucks with 94 compressed biomethane trucks and 296 compressed hydrogen trucks.
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    Motivations, incentives, and commitments: financial benefits and citizen participation in onshore wind energy in Ireland
    (University College Cork, 2023) le Maitre, Julia; Ryan, Geraldine; Power, Bernadette; Horizon 2020; Irish Research Council; Sustainable Energy Authority of Ireland
    Social acceptance of onshore wind energy is a fundamental constraint for the delivery of sustainable electricity supply (Wüstenhagen et al., 2007). For a country such as the Republic of Ireland, this is a significant impediment to the decarbonisation of the energy sector (Brennan et al., 2017; Hallan and González, 2020; Van Rensburg et al., 2015), since onshore wind energy is expected to increase from approximately a third of the electricity mix to 80% by 2030 (SEAI, 2023). In 2019, Ireland introduced the Renewable Electricity Support Scheme with the aim of quadrupling its supply of onshore wind energy. The policy introduced a variety of financial benefits directed towards local communities to facilitate social acceptance, including community benefit funding and incentives focused on households closest to the wind farm, in the form of ‘near-neighbour’ compensation (DECC, 2021). The scheme also opened consideration for a new mechanism to encourage citizen investment into wind farms (DCCAE, 2020). The novelty, scope, and value of these mechanisms underscore the need for detailed research to identify how they could be designed and implemented to enhance their fairness, benefit, and acceptance. This thesis asks how specific attributes of financial participation mechanisms aimed at enhancing social acceptance influence citizens' willingness to accept, or to invest in, wind farms in their community. This thesis is based on two specialised surveys to examine how Irish citizens trade-off between different features of wind farm developments and their associated financial benefits. The research provides detailed insights into the preferences of supporters, conditional supporters, and non-supporters for wind farm developments in the community and presents recommendations concerning distributive and procedural issues across each phase of project development. Firstly, the findings show that citizens’ preferences for the distribution of financial benefits from wind farms are affected by procedural factors over planning, construction, and operation. Community participation in the governance of the community benefit fund and in the ownership of the wind farm have particularly high relative importance for strong supporters of wind farms. In addition, the developer and the proximity of the wind farm strongly influence willingness to accept. Secondly, the thesis contributes new evidence towards the design of citizen wind energy investments, and reveals a strong relationship between community acceptance, the proximity of the wind farm, and citizen investment preferences. Overall, financial attributes including the level of risk and expected return on investment have the greatest influence on citizen investment. However, the structure of voting rights, ownership and administration of the investment are generally regarded as having a higher relative importance if the wind farm is within 2km of the community, or a respondent is supportive of wind energy development. Thirdly, familiarity with a wind farm, whether a result of its proximity or phase of development, is a significant determinant of residents’ willingness to accept further development in the community. Critical points for local support of wind farms are at the earliest pre-planning / planning phases of development, as well as for households within the 2km radius of a wind farm. Other latent factors, such as attitudes towards wind electricity, trust in information provided by a developer, or awareness of community energy initiatives significantly affect community acceptance. Lastly, a comparative case study analyses the design of financial benefits, citizen investment and near-neighbour incentives in Ireland with corresponding mechanisms introduced by Denmark, Germany, and the United Kingdom. Based on a critical assessment of the design and adaptation of policy mechanisms over time, the findings suggest that it is becoming more common for these governments to endorse the development of community trusts or municipality community benefit funds. It also suggests that community-led wind farms experience difficulties related to the competitive nature of the auction regime. The chapter recommends that when defining eligibility or boundaries on citizen financial participation, policymakers could use a phased approach, first prioritising residents closest to a wind farm, and then opening opportunities across a wider geography in the second instance. The research is relevant for policy and practice. It enhances the understanding of citizens’ preferences for financial participation mechanisms in onshore wind farms, which is conducive to social acceptance and fairer local energy transitions. It would be valuable for future studies to develop on this evidence in the context of offshore wind energy and demand-side response which are increasingly important for the Irish energy transition. The diffusion of these innovative technologies similarly depends on citizen participation, fairness, and ultimately social acceptance.