Date of Award


Document Type

Master Thesis

Degree Name

Master of Engineering (Research)


Civil, Structural & Environmental Engineering

First Advisor

Mr. Leonard O'Driscoll


Climate change is brought about by greenhouse gases emitted to the earth’s atmosphere by fossil fuels. Renewable energy sources are seen as an alternative to fossil fuels. Examples of renewable energy sources are biofuels which are a method of reducing the emission of greenhouse gases. One form of biofuels is biogas that is produced during the anaerobic digestion process. In this thesis pig slurry is used to produce biogas.

In this project, the optimum design process for a centralised anaerobic digestion plant was established in the literature review, The optimum process for anaerobic digestion plant design in Ireland was investigated. The proposed feedstock for the centralised anaerobic digestion plant was pig slurry.

As part of this work a Microsoft Excel spreadsheet was developed to determine the size of digester tanks depending on farm sizes. A technical, environmental and financial analysis was conducted on various size anaerobic digestion plants. These analyses provided the number of houses a pig farm could provide with heat and power and the amount of vehicles each pig farm could generate methane gas for.

A mechanical and process design was carried out on an anaerobic digestion plant for pig farmers. Elements of the anaerobic plant were designed such as the roof system, heating system, agitators, pumps and pipes. A process design incorporating control valves to monitor the temperature of the pig slurry entering the digester was also conducted.

Laboratory work was undertaken to confirm that the theoretical values for pig slurry used in the technical analysis in chapter three were correct. The methane gas generated from five samples of pig slurry was recorded.

A structural design was also developed for design of the reinforced concrete digester tanks to the Eurocode. A Microsoft Excel spreadsheet determined the wall thickness and steel required are suitable to ensure crack widths are limited in the digester tank. The digester tanks were also sized with a reinforced concrete heel to prevent flotation in case of a high water table.

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