Options
Murphy, Fionnuala
Preferred name
Murphy, Fionnuala
Official Name
Murphy, Fionnuala
Research Output
Now showing 1 - 10 of 18
- PublicationGreenhouse gas and energy based life cycle analysis of products from the Irish wood processing industryThe timber industry in Ireland is an important producer of wood products for export and indigenous use, and supplies significant volumes of sawmill co-products as biomass for energy generation. This research expands existing knowledge on the environmental impacts of wood supply chains in Ireland by widening the analysis to incorporate the wood processing stage. The study determines and analyses energy and material inputs in the production of several timber products; sawnwood, wood chip, wood-based panel (WBP) boards and wood pellets, with an analysis of the resulting greenhouse gas emissions. Forestry operations and transportation make an important contribution to overall emissions. Electricity usage is responsible for the majority of emissions in sawmilling. Integration of combined heat and power (CHP) systems with sawmilling and pellet manufacture reduces greenhouse gas (GHG) emissions. The penetration of renewables in the Irish national grid mix is forecast to increase by 2020 in line with EU renewable energy targets. Analysis shows that the forecast fall in the carbon intensity of the grid will have a positive effect on the reduction of GHG emissions from the wood processing supply chains. Wood energy products compare favourably with other sources of biomass energy and with fossil fuels.
1128Scopus© Citations 46 - PublicationForest Biomass Supply Chains in Ireland: A Life Cycle Assessment of GHG Emissions and Primary Energy BalancesThe demand for wood for energy production in Ireland is predicted to double from 1.5 million m3 over bark (OB) in 2011 to 3 million m3 OB by 2020. There is a large potential for additional biomass recovery for energetic purposes from both thinning forest stands and by harvesting of tops and branches, and stumps. This study builds on research within the wood-for-energy concept in Ireland by analysing the energy requirements and greenhouse gas emissions associated with thinning, residue bundling and stump removal for energy purposes. To date there have been no studies on harvesting of residues and stumps in terms of energy balances and greenhouse gas emissions across the life cycle in Ireland. The results of the analysis on wood energy supply chains highlights transport as the most energy and greenhouse gas emissions intensive step in the life cycle. This finding illustrates importance of localised production and use of forest biomass. Production of wood chip, and shredded bundles and stumps, compares favourably with both other sources of biomass in Ireland and fossil fuels.
908Scopus© Citations 56 - PublicationMiscanthus production and processing in Ireland: An analysis of energy requirements and environmental impactsThe environmental impact of bioenergy supply systems can be determined using life cycle assessment methodologies. This study focuses on the impact of production of Miscanthus pellets and briquettes, potentially used to satisfy renewable energy requirements in Ireland. The impact categories considered are particularly important when assessing bioenergy systems; global warming potential, acidification potential, eutrophication potential, and energy demand. The scope of the study incorporates Miscanthus cultivation, harvest, processing and transport to a biomass distributor. The aim of the research is to evaluate the effects of changes in keys variables on the overall environmental impacts of the system. The scenarios examined include replacement of synthetic fertilisers with biosolids, Miscanthus processing by pelleting and briquetting, and transport distances of 50 and 100 km. Results indicate that maintenance and processing of the Miscanthus crop have the most environmental impacts with transport having less of an effect. Replacing synthetic fertiliser with biosolids results in a reduction in global warming potential of 23–33% and energy demand of 12–18%, but raises both acidification and eutrophication potential by 290–400% and 258–300%, respectively. Pelleting of Miscanthus requires more energy than briquetting, hence has higher impacts in each category assessed. Increasing the transport distance from 50 to 100 km, results in a small increase in each impact category. Miscanthus briquette production compares favourably with wood pellet, kerosene, and coal production, with Miscanthus pelleting proving more environmentally damaging.
569Scopus© Citations 44 - PublicationBenchmarking Environmental Impacts of Peat Use for Electricity Generation in Ireland - A Life Cycle AssessmentThe combustion of peat for energy generation accounts for approximately 4.1% of Ireland’s overall greenhouse gas (GHG) emissions, with current levels of combustion resulting in the emission of 2.8 Mt of CO2 per annum. The aim of this research is to evaluate the life cycle environmental impacts of peat use for energy generation in Ireland, from peatland drainage and industrial extraction, to transportation, combustion, and subsequent after-use of the cutaway area, utilising Irish-specific emission factors. The environmental impacts considered are global warming potential, acidification potential, and eutrophication potential. In addition, the cumulative energy demand of the system is evaluated. Previous studies on the environmental impact of peat for energy in Ireland relied on default Intergovernmental Panel on Climate Change (IPCC) emission factors (EFs). This research utilises Irish-specific EFs and input data to reduce uncertainty associated with the use of default IPCC EFs, and finds that using default IPCC EFs overestimates the global warming potential when compared to Irish-specific EFs by approximately 2%. The greatest contribution to each of the environmental impacts considered arises from emissions generated during peat combustion, which accounts for approximately 95% of each of the environmental impact categories considered. Other stages of the life-cycle, such as impacts emanating from the peat extraction area, fossil fuel usage in harvesting and transportation machinery, and after-use of the cutaway area have much smaller effects on overall results. The transformation of cutaway peatlands to different after-use alternatives has the potential to mitigate some of the effects of peatland degradation and peat combustion.
437Scopus© Citations 13 - PublicationMiscanthus production and processing in Ireland: An analysis of energy requirements and environmental impactsThe environmental impact of bioenergy supply systems can be determined using life cycle assessment methodologies. This study focuses on the impact of production of Miscanthus pellets and briquettes, potentially used to satisfy renewable energy requirements in Ireland. The impact categories considered are particularly important when assessing bioenergy systems; global warming potential, acidification potential, eutrophication potential, and energy demand. The scope of the study incorporates Miscanthus cultivation, harvest, processing and transport to a biomass distributor. The aim of the research is to evaluate the effects of changes in keys variables on the overall environmental impacts of the system. The scenarios examined include replacement of synthetic fertilisers with biosolids, Miscanthus processing by pelleting and briquetting, and transport distances of 50 and 100 km. Results indicate that maintenance and processing of the Miscanthus crop have the most environmental impacts with transport having less of an effect. Replacing synthetic fertiliser with biosolids results in a reduction in global warming potential of 23–33% and energy demand of 12–18%, but raises both acidification and eutrophication potential by 290–400% and 258–300%, respectively. Pelleting of Miscanthus requires more energy than briquetting, hence has higher impacts in each category assessed. Increasing the transport distance from 50 to 100 km, results in a small increase in each impact category. Miscanthus briquette production compares favourably with wood pellet, kerosene, and coal production, with Miscanthus pelleting proving more environmentally damaging.
763Scopus© Citations 44 - PublicationThe evaluation of viscosity and density of blends of Cyn-diesel pyrolysis fuel with conventional diesel fuel in relation to compliance with fuel specifications EN 590:2009The production of synthetic fuels from alternative sources has increased in recent years as a cleaner, more sustainable source of transport fuel is now required. In response to European renewable energy targets, Ireland has committed, through the Biofuels Obligation Scheme of 2008, to producing 4% of transport fuels from biofuels by 2010 and 10% by 2020. In order to be suitable for sale in Europe, diesel fuels and biodiesels must meet certain European fuel specifications outlined in the EN 590:2004 and EN 14214:2009 standards. The aim of this project is to prepare blends of varying proportions of synthetic diesel fuel (Cyn-diesel), produced from the pyrolysis of plastic, versus regular fossil diesel. The viscosity (mm2/s) and density (kg/m3) of these blends as well as of the regular diesel fuel were analysed in relation to compliance with the European fuel standard EN 590.
1166Scopus© Citations 13 - PublicationLife cycle assessment of biomass-to-energy systems in Ireland modelled with biomass supply chain optimisation based on greenhouse gas emission reductionThe energy sector is the major contributor to GHG (greenhouse gas emissions) in Ireland. Under EU Renewable energy targets, Ireland must achieve contributions of 40%, 12% and 10% from renewables to electricity, heat and transport respectively by 2020, in addition to a 20% reduction in GHG emissions. Life cycle assessment methodology was used to carry out a comprehensive, holistic evaluation of biomass-to-energy systems in 2020 based on indigenous biomass supply chains optimised to reduce production and transportation GHG emissions. Impact categories assessed include; global warming, acidification, eutrophication potentials, and energy demand. Two biomass energy conversion technologies are considered; co-firing with peat, and biomass CHP (combined heat and power) systems. Biomass is allocated to each plant according to a supply optimisation model which ensures minimal GHG emissions. The study shows that while CHP systems produce lower environmental impacts than co-firing systems in isolation, determining overall environmental impacts requires analysis of the reference energy systems which are displaced. In addition, if the aims of these systems are to increase renewable energy penetration in line with the renewable electricity and renewable heat targets, the optimal scenario may not be the one which achieves the greatest environmental impact reductions.
711Scopus© Citations 42 - PublicationA Feasibility Assessment of Photovoltaic Power Systems in Ireland; a Case Study for the Dublin RegionPhotovoltaic (PV) power generation is one of the cleanest sources for producing renewable energy; however uptake on the Irish renewable energy market to date has been low. There is a lack of support for solar PV systems in Ireland; there is currently no solar PV energy feed-in-tariff as there are for other renewable energy systems in Ireland. Despite the current lack of support, the Government has indicated that support for the uptake of solar PV installations will be provided through the provision of a feed-in tariff in the future. The aim of this study was to determine the feasibility of installing PV systems under Irish climatic conditions at a location based in Dublin, Ireland, from a technical, environmental and economic point of view. This was achieved by carrying out a life cycle assessment of potential environmental impacts, and analysis of energy and economic payback times relating to the proposed PV system. Four possible renewable feed-in-tariffs (based on existing feed-in-tariffs for other renewable energy systems) were considered to determine the effect of such tariffs on the overall economics of the proposed PV system. Results show that life cycle GHG emissions are 69 g CO2-eq per kWh generated by the system, significantly lower than the current electricity grid mix emissions of 469 g CO2-eq per kWh. It will take 5.23 years of operation of the solar plant to generate the same amount of energy (in terms of primary energy equivalent) that was used to produce the system itself. The economic payback time varies from 19.3 and 34.4 years depending on the rate of renewable energy feed-in-tariff applied. The costs for the production of PV electricity in this study are higher than is usual in countries where the solar PV market is more developed, e.g., Germany, due to constraints with building integration and lack of experienced PV installers. As more PV is deployed, the Irish PV installer base will increase and ‘learning by doing’ effects will allow installers to install projects more efficiently and quickly under Irish conditions, leading to significantly reduced costs.
920Scopus© Citations 27 - PublicationBiofuel Production in Ireland—An Approach to 2020 Targets with a Focus on Algal BiomassUnder the Biofuels Obligation Scheme in Ireland, the biofuels penetration rate target for 2013 was set at 6% by volume from a previous 4% from 2010. In 2012 the fuel blend reached 3%, with approximately 70 million L of biodiesel and 56 million L of ethanol blended with diesel and gasoline, respectively. Up to and including April 2013, the current blend rate in Ireland for biodiesel was 2.3% and for bioethanol was 3.7% which equates to approximately 37.5 million L of biofuel for the first four months of 2013. The target of 10% by 2020 remains, which equates to approximately 420 million L yr−1. Achieving the biofuels target would require 345 ktoe by 2020 (14,400 TJ). Utilizing the indigenous biofuels in Ireland such as tallow, used cooking oil and oil seed rape leaves a shortfall of approximately 12,000 TJ or 350 million L (achieving only 17% of the 10% target) that must be either be imported or met by other renewables. Other solutions seem to suggest that microalgae (for biodiesel) and macroalgae (for bioethanol) could meet this shortfall for indigenous Irish production. This paper aims to review the characteristics of algae for biofuel production based on oil yields, cultivation, harvesting, processing and finally in terms of the European Union (EU) biofuels sustainability criteria, where, up to 2017, a 35% greenhouse gas (GHG) emissions reduction is required compared to fossil fuels. From 2017 onwards, a 50% GHG reduction is required for existing installations and from 2018, a 60% reduction for new installations is required.
1213Scopus© Citations 72 - PublicationA Feasibility Analysis of Photovoltaic Solar Power for Small Communities in IrelandPhotovoltaic power generation is one of the cleanest sources for producing renewable energy, however to date its up take on the Irish renewable energy market has been extremely low. Through research carried out on regions where these technologies are widely used and developed, this project investigates the feasibility of using photovoltaic systems to generate power under Irish climatic conditions. This involved a comparative investigation between solar insolation in Ireland and in regions currently using Photovoltaic systems. This projects main aim was to identify if photovoltaic systems were a feasible source of power generation for a sustainable community of 130 eco-friendly homes based on the fact that they are built to B1 energy rating standards. B1 implies an energy use of between 75kwh/m²/yr and 100kwh/m²/yr. Results showed that houses of 140 m² have a PV area requirements ranging from 20 m² - 26 m², while the larger live/work units of 195 m² have an area requirement of 27 m² - 36 m². While the communal solar park has an area requirement of 2665 m² - 3553 m² without spacing, this however will differ when space requirements are calculated to prevent overshadowing. The results obtained prove that such systems are feasible, however may be dependent on governmental support or grants. The installation of such a system would not only provide benefits to the members of this eco-village through production of on-site energy, but also to national legislation relating to reduced CO2 emissions and increases in the percentage share of renewables in gross national electricity consumption. The results suggest that this system could produce between 1431000 - 1908000 kWh per year, enough to sufficiently supply the community, while producing excess energy for three-quarters of the year, while displacing between 283338 - 377784 kg/ CO2/yr.
3629