Feasibility study of an off-grid biomethane mobile solution for agri-waste

Research shows that gas grid injection of upgraded biogas is very advantageous in maximizing energy recovery. However, the majority of farms are more than 10 km away from the gas network in Ireland, therefore transporting biomethane by road to suitable injections points on the gas network would maximize the mobilization of potential biomethane resources. This represents both a challenge and an opportunity in getting to market. A model was developed to describe an off-grid biomethane virtual pipeline solution (cleaning, upgrading and storage mobile units) for small-scale farm biogas plants located at more than 10 km from the gas grid system. The cost for 1 Nm³ of biomethane, transported and injected into the gas grid was calculated between €0.62 and €0.80. The model evaluates different scenarios, which differ in the number and size of biogas plants. Comparisons are made to a traditional upgrading model. The model showed that the off-grid biomethane mobile (virtual pipeline) solution costs are €0.18/Nm³ lower than in a configuration of onsite upgrading plants at a biogas production rate of 150 m³/hour. This solution was found to be critical to the development of the wider biomethane industry in countries where direct access to the gas grid is limited by remote location and/or grid injection capacities in some parts of the network capacity.