Date of Award


Document Type

Master Thesis

Degree Name

Master of Engineering (Research)


Civil, Structural & Environmental Engineering

First Advisor

Dr. Niamh Power

Second Advisor

Dr. Jerry D. Murphy


According to the EU Renewables Directive 2009/28/EC, 20% of the energy across Europe needs to be renewable by 2020. This is inclusive of the energy utilised in the transport sector where 10% of this energy needs to be renewable. In order for Ireland to meet the targets set in the Renewables Directive various changes need to be applied. The utilisation of gaseous biofuels produced from the anaerobic digestion of various feedstocks will aid Ireland in meeting this directive.

In this study biodegradable municipal waste (BMW) and energy crops are analysed as potential feedstocks for the production of biomethane. This biomethane can be utilised as a transport fuel. The use of BMW as a feedstock will aid Ireland in meeting the EU Landfill Directive 1999/31/EC as this directive sets out limits for the quantity of BMW going to landfill for 2010, 2013 and 2016. The diversion of BMW away from landfill to be utilised in the production of biomethane as a transport fuel thus complies with these two directives. A combined approach is deemed the optimal approach which includes 22 facilities and is capable of fuelling 122,469 ears, making approximately €200 million revenue and saving over 1.3 million tC02 annually. Various energy crops are analysed to determine the optimal energy crop. Barley, oats and grass silage are investigated. These crops are co-digested to determine the optimal crop rotation. The optimal crop rotation is grass silage on its own on an 875ha land area and is capable of fuelling 5.36 ears per hectare, making €156,562 revenue and saving 7,802 tC02 annually.

The production of hydrogen gas and biogas is also examined in a two phase process known as the dark fermentation process. Hydrogen gas is produced in the initial fermentation phase. The effluent from this phase is utilised as substrate in the second phase and biogas is thus produced. These two fuels can be used as a transport fuel. BMW and the optimal crop (grass silage) are investigated as a potential feedstock for this process. BMW can potentially fuel a total of 8,592 ears, make a revenue of €13,681,789 and save 57,990tCO2 annually for the 75,000tpa facility while grass silage can fuel 4,388 cars, make a revenue of €715,753, however this process produces 1,754 tC02 for the 875ha land area.

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