Fionnuala Murphy | University College Dublin (original) (raw)

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Papers by Fionnuala Murphy

Renewable and Sustainable Energy Reviews, 2013

The timber industry in Ireland is an important producer of wood products for export and indigenou... more The 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.

GCB Bioenergy, Sep 11, 2013

Willow Salix sp. is currently cultivated as a short rotation forestry crop in Ireland as a source... more Willow Salix sp. is currently cultivated as a short rotation forestry crop in Ireland as a source of biomass to contribute to renewable energy goals. The aim of this study is to evaluate the energy requirements and environmental impacts associated with willow (Salix sp.) cultivation, harvest, and transport using life cycle assessment (LCA). In this study, only emissions from the production of the willow chip are included, end-use emissions from combustion are not considered. In this LCA study, three impact categories are considered; acidification potential, eutrophication potential and global warming potential. In addition, the cumulative energy demand and energy ratio of the system are evaluated. The results identify three key processes in the production chain which contribute most to all impact categories considered; maintenance, harvest and transportation of the crop. Sensitivity analysis on the type of fertilizers used, harvesting technologies and transport distances highlights the effects of these management techniques on overall system performance. Replacement of synthetic fertilizer with biosolids results in a reduction in overall energy demand, but raises acidification potential, eutrophication potential and global warming potential. Rod harvesting compares unfavourably in comparison with direct chip harvesting in each of the impact categories considered due to the additional chipping step required. The results show that dedicated truck transport is preferable to tractor-trailer transport in terms of energy demand and environmental impacts. Finally, willow chip production compares favourably with coal provision in terms of energy ratio and global warming potential, while achieving a higher energy ratio than peat provision but also a higher global warming potential.

Applied Energy, Mar 2014

The demand for wood for energy production in Ireland is predicted to double from 1.5 million m3 o... more The 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.

Renewable and Sustainable Energy Reviews, Jul 2013

The environmental impact of bioenergy supply systems can be determined using life cycle assessmen... more The 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.

The Open Fuels & Energy Science Journal, 2013

The production of synthetic fuels from alternative sources has increased in recent years as a cle... more The production of synthetic fuels from alternative sources has increased in recent years as a cleaner, more sustainable source of transport fuel is now required. The European Commission has outlined renewable energy targets pertaining to transport fuel which must be met by 2020. In response to these targets Ireland has committed, through the Biofuels Obligation Scheme of 2008, to producing 3% 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 590:2009 standard. The aim of this paper was to prepare blends of varying proportions of synthetic diesel (Cyn diesel) fuel, produced from the pyrolysis of plastic, vs regular fossil diesel. The flash point (°C) and cold filter plugging point (°C) of these blends as well as of the conventional petroleum diesel fuel were analysed in relation to compliance with the European fuel standard EN 590. The results confirmed that blending of Cyn diesel with conventional petroleum diesel has a highly significant effect on the properties of the resulting fuel blend. The results show that by increasing the Cyn-diesel content of the blend, the flash point of the blend decreases and the cold filter plugging point increases. Furthermore, comparing the fuel blends to EN 590 specifications has highlighted significant trends. The cold filter plugging points of all of the fuel blends are in compliance with EN 590 specifications. However, only blends of up to, and including, 40% Cyn-diesel are in compliance with EN 590 specifications for flash point. This analysis shows that a blend of 40% Cyn-diesel is in compliance with all of the EN 590 specifications examined, and as such could be placed on the European fuel market (provided that the blend meets the requirements for the other properties in the EN 590 specification). This finding highlights the potential for Cyn-diesel blends to be incorporated into the European and national renewable energy targets.

Fuel, Jan 2012

Energies, Dec 2013

Under the Biofuels Obligation Scheme in Ireland, the biofuels penetration rate target for 2013 wa... more Under 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.

Renewable and Sustainable Energy Reviews, Jul 2014

The biofuels penetration rate target in Ireland for 2013 is 6% by volume. In 2012 the fuel blend ... more The biofuels penetration rate target in Ireland for 2013 is 6% by volume. In 2012 the fuel blend reached 3%, with approximately 70 million litres of biodiesel and 56 million litres of ethanol blended with diesel and gasoline respectively. For January and February 2013, the blend rate had only reached 2.7%. The target of 10% by 2020 remains which equates to approximately 420 million litres. Achieving the biofuels target would require 345 ktoe by 2020 (14,400 TJ). Utilising the indigenous biofuels outlined in this paper leaves a shortfall of approximately 12,000 TJ or 350 million litres (achieving 17% of the 10% target) that must be either be imported or met by other renewables. 70% of indigenous production from one biodiesel plant is currently from TME and UCOME. If this remains for 2020 then only 30% remains equating to approximately 10 million litres indigenous production for a second biodiesel plant (30% of 21+13 million litres) which has planned capacity of 40 million litres (36,000 t). In terms of the EU biofuels sustainability criteria, up to 2017, a 35% GHG emissions reduction is required compared to fossil fuels. From 2017 onwards, a 50% GHG reduction is required for existing installations and a 60% reduction for new installations.