Gas Network Preparations for Networked Geothermal

Abstract

As Massachusetts pursues its goal of achieving net-zero carbon emissions by 2050, the transition from natural gas to sustainable thermal energy solutions presents both opportunities and challenges for its 1.6 million natural gas customers. This thesis investigates the potential of networked geothermal systems as a viable alternative to traditional natural gas infrastructure, with a focus on leveraging existing gas network replacement programs, such as the Gas System Enhancement Plan (GSEP), to facilitate this shift. A four-phase methodology —encompassing site selection, model development, cost analysis, and business case formulation— evaluates the feasibility of integrating high-density polyethylene (HDPE) piping into leak-prone pipe replacement efforts as a preparatory step for future geothermal or hydrogen applications. Findings suggest that HDPE offers potential material and inventory cost advantages over medium-density polyethylene (MDPE), with added flexibility for low-carbon conversions, though significant upfront costs and regulatory uncertainties remain barriers. An example site already scheduled for main replacement work showed a 6% total increase in cost for the project based on the change in pipe from MDPE to HDPE. This work underscores the potential of aligning infrastructure modernization with climate goals, offering a framework for utilities like National Grid to navigate the energy transition in cold, densely populated regions.