The Eavor-LoopTM, a multilateral closed-loop geothermal system (MCLGS), is introduced as a zero-emission load-following resource (ZELFR) that is globally scalable and can provide baseload or dispatchable electricity. For any electrical grid to reach net-zero, ZELFR or largescale energy storage is required to balance intermittent renewables like solar and wind and provide grid stability. Given the declining costs of intermittent renewables and their increased utilization in modern grids, the ability to load follow is both crucial and highly valued. The objectives of this paper are two-fold. First, we prove the technical feasibility of MCLGS to provide flexible power using first principles-based models. Second, we demonstrate the value enhancement of flexible operation with a case study of the United States Western Interconnection power transmission grid using an electricity resource capacity expansion model. A transient, fully coupled wellbore + thermal model was developed and validated using over a year of operating data from the Eavor-LiteTM facility, a full-scale Eavor-LoopTM demonstration project in Alberta, Canada. Recent modelling work, coupled with field trials, has proven the feasibility of Eavor-LoopTM to provide flexible energy for load-balancing or peak-matching with a minimal impact on lifetime energy extraction. Transient operation allows the system to recharge during low demand periods. To demonstrate the value of Eavor-LoopTM in a net-zero grid, an electricity resource capacity expansion model (GenX) was used. GenX is a constrained optimization model that determines the mix of electricity generation and storage required to meet electricity demand while minimizing system cost. Flexible Eavor-LoopTM operation provides stability for the grid, matching electricity generation with demand, and reduces annual total system cost by up to $20B (21%) in a base case and up to $403B (81%) in an extreme case. Inclusion of Eavor-LoopTM also reduces land use required by up to 49%, saving 25 acres in a base case and 48 acres in an extreme case for each megawatt of Eavor-LoopTM installed.