Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Civil, Structural & Environmental Engineering

First Advisor

Dr. Niamh Power

Second Advisor

Des Walsh


Greenhouse gas (GHG) emissions from the transport industry is a major environmental issue which the world currently faces. In Ireland, the transport sector accounted for 19% of its total GHG emissions in 2015 which is projected to increase to 29% by 2030. The European Union Renewable Energy Directive (2009/28/EC) mandates Ireland to achieve a 10% share of renewable energy sources in transport (RES-T) by 2020. The Irish Government proposes to achieve the RES-T through biofuels (9%) and electric vehicles (1%). However, in 2016 the RES-T of Ireland stood at 5.0% and requires significant renewable energy penetration to reach the 2020 target. With the current strategy struggling, the author is motivated to look at an alternative form of renewable transport energy, namely biomethane to bridge to RES-T gap to 2020 and beyond. This body of research develops a strategic policy framework to initiate a biomethane transport market by determining the best utilisation route to market (14,000 commercial vehicles) for the biomethane potential identified (11 biomethane facilities), addressing the technical and infrastructural requirements (22 refuelling stations) to contribute to a RES-T of 1%. There is also significant potential to expand on this market once developed which would provide a RES-T of 11%.

This body of research has heavily influenced academic research in which 37 citations have currently been received. From a policy perspective, proposals to simplify the regulatory regime for the public supply of bio-CNG in this research has been implemented by the Commission for Regulation of Utilities, offering such market participants a significantly less onerous route to market. This research culminates with a proposal to introduce a set of devised regulatory, policy and safety frameworks that are currently in development to introduce the first biomethane injection facility into the natural gas network of Ireland. In conclusion, this body of research has developed an all-encompassing strategy to initiate an effective biomethane transport market through the determination that the captive fleet offers the optimum pathway to penetrate the fossil fuel transport sector, with the significant biomethane potential identified once the proposed infrastructural, regulatory, safety and policy frameworks are implemented to overcome the many highlighted barriers stalling market development.


This work was funded by the Environmental Protection Agency under the Science, Technology, Research and Innovation for the Environment (STRIVE) Programme 2007-2013.

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Chapter 9: Under Peer Review

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