Modeling Reservoir Circulation and Economic Performance of the Neal Hot Springs Geothermal Power Plant (Oregon, U.S.): An Integrated Case Study

Abstract

We review the key factors that facilitated the successful development of a geothermal reservoir at Neal Hot Springs (NHS), Oregon, by a private company. The NHS geothermal field development plan, financing tools, and fluid circulation model provide a template for the development time, financing and well rates required to sustain geothermal power generation in similar setups elsewhere. The early economic performance and life-cycle analysis are specified using company data, applying a financial evaluation tool developed by the National Renewable Energy Laboratory (NREL). The Neal Hot Springs geothermal project was enabled by a combination of financing sources: U.S. federal loan guarantee and cash grant, state tax credit and private equity. Flow patterns in the NHS geothermal reservoir are visualized using a novel streamline simulation tool applying known well rates and benchmarking the residence time of re-injected brine based on tracer tests performed by the company. Temperature of produced brine has stayed remarkably constant over the first years of NHS plant operations, which we ascribe to advection of heat by an upwelling far-field flow beneath the plant’s production wells.