Sustainable design and operation of shale gas supply chain networks with life cycle economic and environmental optimisation

In this work, we address the functional-unit based life cycle optimisation of the design and operations of shale gas supply chain networks considering both the economic and environmental performance. The system covers the well-to-wire life cycle of electricity generated from shale gas, consisting of a number of stages including freshwater acquisition, shale well drilling, fracking, and completion, shale gas production, wastewater management, shale gas processing, electricity generation as well as transportation and storage. The resulting problem is formulated as a multi-objective non-convex mixedinteger nonlinear programming (MINLP) problem. By solving this problem with a global optimisation algorithm, we obtain the Pareto-optimal frontier, which reveals the trade-off between the economic and environmental objectives. A case study based on the Marcellus shale play shows that the environmental impact of shale gas generated electricity ranges from 454 to 508 kg CO₂eq/MWh, and the levelised cost of electricity ranges from 66 to 170 $/MWh.