The challenge of implementing green gas into the gas supply

In order to gain a more mature share in the future energy supply, green gas supply chains face some interesting challenges. The thesis addresses the question how future green gas systems may look like. Green gas supply chains, based on co-digestion of cow manure and maize, have been studied. The produced biogas is upgraded to natural gas quality and injected into the existing distribution gas grid and thus replacing natural gas. A practical way of calculating the cost price of green gas was developed, taking scale and sustainability criteria into account. The way such supply chains can deal with season dependent gas demand was also investigated. Results show that, to meet such a gas demand by a green gas supply chain, flexible biogas production is the most promising from a cost price point of view. This research was further expanded into a geographical model to simulate several degrees of natural gas replacement by green gas. Finally, ways to optimize green gas supply chains in terms of energy efficiency and greenhouse gas reduction were explored. It was shown that with the current technology greenhouse gas reductions of more than 80 % are possible. Multiple improvement options will have to be implemented in green gas supply chains, in order to meet the sustainability targets set by the EU. Overall it can be concluded that the used modeling approach gives opportunities to investigate variations in green gas supply chains in a practical way. Future research may comprise flexible biogas production and a useful application of digestate. An extension of this research may be the further exploration of possible biogas production locations, together with governments, farmers and other stakeholders. Optimal use of arable land and waste streams are part of this