Sean O Connor

Optimal plant design and management are critical components for the successful operation of farm-scale anaerobic digestion (AD) plants. However, this often proves challenging due to difficulties in designing and sizing the plant based on specific site conditions. The current investigation aims to address these difficulties by developing a universal decision support tool to assist in the optimal design and management of agriculture-based AD plants, accounting for site-specific practicalities and… Show more

Optimal plant design and management are critical components for the successful operation of farm-scale anaerobic digestion (AD) plants. However, this often proves challenging due to difficulties in designing and sizing the plant based on specific site conditions. The current investigation aims to address these difficulties by developing a universal decision support tool to assist in the optimal design and management of agriculture-based AD plants, accounting for site-specific practicalities and implications. The tool consists of various mathematical functions, which enable numerous simulations to be created and run. The developed tool was applied to a case study, located in Ireland, to test its usefulness, where the analysis showed the optimal, site-specific, plant design with key assessment indicators. For this case study, the feedstock availability assessment determined that the lignocellulose and non-lignocellulose biomass within a 10 km distance of the site. Based on the local energy demand of the area, the tool modelled an optimal AD plant design, including feedstock storage, digester volume, engine capacity, and digestate storage. The tool applied various technical, economic, and ecological assessment indicators to the plant to gauge its viability. Therefore, demonstrating the tool's usefulness in assisting stakeholders to make informed decisions and reducing costs by optimising plant design and performance. Show less

Small-scale anaerobic digestion (SSAD), i.e. plants with a CHP electrical capacity ranging from 15 to 100 kWe, is a promising technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or standalone waste treatment facilities. In addition to the benefits afforded by traditional plants, SSAD provides greater portability and flexibly options, enabling the technology's implementation in environments previously not… Show more

Small-scale anaerobic digestion (SSAD), i.e. plants with a CHP electrical capacity ranging from 15 to 100 kWe, is a promising technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or standalone waste treatment facilities. In addition to the benefits afforded by traditional plants, SSAD provides greater portability and flexibly options, enabling the technology's implementation in environments previously not justifiable due to insufficient feedstock quantities. Despite the apparent benefits of SSAD, the technology is still not well implemented with much of the research previously conducted focused on large-scale systems. Therefore, a lack of understanding is apparent in the applicability of SSAD plants in stand-alone agricultural environments. To address these challenges, this research aims to evaluate the current-status of SSAD and then implement improvement strategies and technologies.
This PhD study found SSAD to be a viable mechanism for the mitigation of GHG emissions within Irish agriculture environments. It is hoped that the insights generated will make a significant contribution to the future research, development, and application of SSAD technologies and will accelerate efforts to decarbonise the Irish agriculture sector. This research has been carried out under the EU INTERREG funded Renewable Engine project with collaboration from an industry partner (Organic Power). Show less

The use of personal protective equipment (PPE) has become essential to reduce the transmission of coronavirus disease 2019 (COVID-19) as it prevents the direct contact of body fluid aerosols expelled from carriers. However, many countries have reported critical supply shortages due to the spike in demand during the outbreak in 2020. One potential solution to ease pressure on conventional supply chains is the local fabrication of PPE, particularly face shields, due to their simplistic design… Show more

The use of personal protective equipment (PPE) has become essential to reduce the transmission of coronavirus disease 2019 (COVID-19) as it prevents the direct contact of body fluid aerosols expelled from carriers. However, many countries have reported critical supply shortages due to the spike in demand during the outbreak in 2020. One potential solution to ease pressure on conventional supply chains is the local fabrication of PPE, particularly face shields, due to their simplistic design. The purpose of this paper is to provide a research protocol and cost implications for the rapid development and manufacturing of face shields by individuals or companies with minimal equipment and materials. This article describes a best practice case study in which the establishment of a local manufacturing hub resulted in the swift production of 12,000 face shields over a seven-week period to meet PPE shortages in the North-West region of Ireland. Protocols and processes for the design, materials sourcing, prototyping, manufacturing, and distribution of face shields are described. Three types of face shields were designed and manufactured, including Flat, Laser-cut, and 3D-printed models. Of the models tested, the Flat model proved the most cost-effective (€0.51/unit), while the Laser-cut model was the most productive (245 units/day). The insights obtained from this study demonstrate the capacity for local voluntary workforces to be quickly mobilised in response to a healthcare emergency, such as the COVID-19 pandemic. Show less

Anaerobic digestion (AD) has been recognised as an effective means of simultaneously producing energy while reducing greenhouse gas (GHG) emissions. Despite having a large agriculture sector, Ireland has experienced little uptake of the technology, ranking 20th within the EU-28. It is, therefore, necessary to understand the general opinions, willingness to adopt, and perceived obstacles of potential adopters of the technology. As likely primary users of this technology, a survey of Irish cattle… Show more

Anaerobic digestion (AD) has been recognised as an effective means of simultaneously producing energy while reducing greenhouse gas (GHG) emissions. Despite having a large agriculture sector, Ireland has experienced little uptake of the technology, ranking 20th within the EU-28. It is, therefore, necessary to understand the general opinions, willingness to adopt, and perceived obstacles of potential adopters of the technology. As likely primary users of this technology, a survey of Irish cattle farmers was conducted to assess the potential of on-farm AD for energy production in Ireland. The study seeks to understand farmers’ motivations, perceived barriers, and preferred business model. The study found that approximately 41% of the 91 respondents were interested in installing AD on their farming enterprise within the next five years. These Likely Adopters tended to have a higher level of education attainment, and together, currently hold 4379 cattle, potentially providing 37,122 t year−1 of wastes as feedstock, resulting in a potential CO2 reduction of 800.65 t CO2-eq. year−1. Moreover, the results indicated that the primary consideration preventing the implementation of AD is a lack of information regarding the technology and high investment costs. Of the Likely Adopters and Possible Adopters, a self-owned and operated plant was the preferred ownership structure, while 58% expressed an interest in joining a co-operative scheme. The findings generated provide valuable insights into the willingness of farmers to implement AD and guidance for its potential widespread adoption. Show less

Small-scale anaerobic digestion (SSAD) is a promising technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or in stand-alone waste treatment facilities. SSAD systems can transform organic matter into biogas (a mixture, mainly composed of carbon dioxide and methane), making the technology suitable for a variety of applications in energy, agriculture and, potentially, the emerging bio-products and bio-processes… Show more

Small-scale anaerobic digestion (SSAD) is a promising technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or in stand-alone waste treatment facilities. SSAD systems can transform organic matter into biogas (a mixture, mainly composed of carbon dioxide and methane), making the technology suitable for a variety of applications in energy, agriculture and, potentially, the emerging bio-products and bio-processes sector. Small-scale farming processes can further exploit the portable and flexible options made available by implementing SSAD systems to effect on-demand conversion of organic waste streams to useful heat (and, potentially, electricity), with significant economic benefits accruable (especially when such energy carriers are exported). SSAD is particularly applicable to the European agricultural sector, where the average individual farm sizes and land productivities are currently insufficient to meet the feedstock requirements of medium and large-scale plants. Despite the apparent benefits of SSAD, the technology is still not well utilised. Much of the research previously conducted has focused on large-scale systems.

This study explores the current status of SSAD technology in Europe by identifying process design and operational characteristics, influential EU policies, the recent progress related to SSAD, and the issues encountered. The study sheds light on an area with limited research by providing an overview of the technology's present status in Europe by identifying areas of future study. Show less

The production of chemicals and industrial raw materials via the application of the anaerobic digestion (AD) process on agricultural and bio-industry derived wastes and by-products has been increasingly discussed. While the implementation of such schemes for raw material production is foreseen to potentially increase the valorisation capacity and the overall circularity of AD systems (i.e. by availing the production of other economic outputs other than the energy carrier methane, CH4)… Show more

The production of chemicals and industrial raw materials via the application of the anaerobic digestion (AD) process on agricultural and bio-industry derived wastes and by-products has been increasingly discussed. While the implementation of such schemes for raw material production is foreseen to potentially increase the valorisation capacity and the overall circularity of AD systems (i.e. by availing the production of other economic outputs other than the energy carrier methane, CH4), widespread implementation of such approaches is still lacking. This chapter provides a comprehensive review of the current state of the art related to AD-based biorefinery approaches and highlights some operational and economical limitations preventing the uptake of such systems. The chapter then further draws attention to some potential candidate processes and products which could be produced from decentralised AD (with a focus on small-scale AD) systems to meet intended biorefinery objectives. Show less

Several threats in the form of climate change, future oil supplies, and energy security have created a need for the development of large-scale alternatives to fossil fuel-based fuels. One such alternative fuel developed from bio-renewable resources, which has generated considerable interest, is biodiesel, mainly produced via the transesterification of animal fats and vegetable oils.

Organic and inorganic solvents have been commonly applied to improve the efficiency of the biodiesel… Show more

Several threats in the form of climate change, future oil supplies, and energy security have created a need for the development of large-scale alternatives to fossil fuel-based fuels. One such alternative fuel developed from bio-renewable resources, which has generated considerable interest, is biodiesel, mainly produced via the transesterification of animal fats and vegetable oils.

Organic and inorganic solvents have been commonly applied to improve the efficiency of the biodiesel production process. However, because of the undesirable properties of conventional solvents such as their hazardous nature, the need for greener alternatives is apparent. Over the last decade, ionic liquids (ILs) have garnered considerable attention for both their process improvement and environmental benefits to the biodiesel production process. In this chapter, a compressive overview is provided of the versatility of ILs as solvents in both the reaction and purification steps in the biodiesel production process, acting as catalysts, co-solvents, and extracting solvents. In addition, this study explores the use of deep eutectic solvents (DESs), which are considered to be the next generation of solvents in the biodiesel production process. Show less

Farm-scale anaerobic digestion (AD) plants face considerable difficulties in sustaining a constant feedstock supply and energy output mainly due to seasonal variabilities. Particularly in small-scale operations, the need to understand and control such variables is apparent to enable a consistent energy output year-round. Furthermore, to ensure the sustained operability and economic viability of such systems, AD plants often have contractual obligations to provide a stable energy output to… Show more

Farm-scale anaerobic digestion (AD) plants face considerable difficulties in sustaining a constant feedstock supply and energy output mainly due to seasonal variabilities. Particularly in small-scale operations, the need to understand and control such variables is apparent to enable a consistent energy output year-round. Furthermore, to ensure the sustained operability and economic viability of such systems, AD plants often have contractual obligations to provide a stable energy output to clients with minimum variations in the quality and quantities of energy produced. Despite the importance of such evaluation and the need for AD operators to have such planning tools available, a literature search conducted showed that no previous assessment of the influence of seasonal variabilities on farm-scale AD plants exists. The purpose of this work is to evaluate the seasonal feedstock supply, parasitic energy consumption and net energy production variabilities of an actual small-scale AD plant (with electrical output <100kw), located at Agri-Food and Biosciences Institute (AFBI) in Northern Ireland. The plant operates on a co-digestion feedstock (grass silage and manure) using a 600m3 mesophilic primarily digester, and with the produced biogas utilised for energy generation in a 95 kW combined heat and power (CHP) unit. This study uses data collected over an eleven-year period to identify seasonal variations in parasitic demand and feedstock characteristics (e.g. quality, supply and demand) to develop a predictive and operational “best practice” matrix which can be applied by the AD operators to achieve a consistent energy output year-round. The developed matrix will highlight the relationship between feed input, external environmental factors, energy input (parasitic), and energy output. This study has been carried out under the EU INTERREG funded Renewable Engine project. Show less

The European Union’s (EU) climate and energy package requires all EU countries to reduce their greenhouse gas (GHG) emissions by 20% by 2020. Based on current trends, Ireland is on track to miss this target with a projected reduction of only 5% to 6%. The agriculture sector has consistently been the single largest contributor to Irish GHG emissions, representing 33% of all emissions in 2017. Small-scale anaerobic digestion (SSAD) holds promise as an attractive technology for the treatment of… Show more

The European Union’s (EU) climate and energy package requires all EU countries to reduce their greenhouse gas (GHG) emissions by 20% by 2020. Based on current trends, Ireland is on track to miss this target with a projected reduction of only 5% to 6%. The agriculture sector has consistently been the single largest contributor to Irish GHG emissions, representing 33% of all emissions in 2017. Small-scale anaerobic digestion (SSAD) holds promise as an attractive technology for the treatment of livestock manure and the organic fraction of municipal wastes, especially in low population communities or standalone waste treatment facilities. This study assesses the viability of SSAD in Ireland, by modelling the technical, economic, and environmental considerations of operating such plants on commercial Irish dairy farms. The study examines the integration of SSAD on dairy farms with various herd sizes ranging from 50 to 250 dairy cows, with co-digestion afforded by grass grown on available land. Results demonstrate feedstock quantities available on-farm to be sufficient to meet the farm’s energy needs with surplus energy exported, representing between 73% and 79% of the total energy generated. All scenarios investigated demonstrate a net CO2 reduction ranging between 2059–173,237 kg CO2-eq. yr−1. The study found SSAD systems to be profitable within the plant’s lifespan on farms with dairy herds sizes of >100 cows (with payback periods of 8–13 years). The simulated introduction of capital subvention grants similar to other EU countries was seen to significantly lower the plant payback periods. The insights generated from this study show SSAD to be an economically sustainable method for the mitigation of GHG emissions in the Irish agriculture sector. Show less