Supercritical CO2 Coaxial Heat Exchanger for Geothermal Well Conversion with ECO2G Technology

Economics, Policy and Business Geothermal Engineering and Exploration Show all

Author: Lauren Hillis

Year: 2017

Supervisors: María Sigríður Guðjónsdóttir, Sverrir Þórhallsson, & Joseph Scherer

Abstract

The feasibility of converting non-producing geothermal wells to closed loop supercritical CO₂ coaxial heat exchanger using ECO2G technology was analyzed for two heat exchanger scenarios. The first scenario, Case A, utilizes the existing production casing as the heat exchanger and plugs the well at 1000 m depth to create the closed loop. The second scenario, Case B, inserts a new, closed, hang-down liner to the full 2500 m depth to use as the heat exchanger. A spreadsheet thermodynamic model discretized the depth of the well to model the heat flow, temperature and pressure of the CO₂, and electricity production of each heat exchanger. With the electricity production, a financial model was created by calculating the net present value and internal rate of return for the project. With the financial model and sensitivity model on electricity prices, a break-even price was found for each case.

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