Tools to Evaluate Strategies for Utilization of Low Temperature Geothermal Resources

Abstract

A tool for making basic evaluations of strategies for utilization of low temperature geothermal resources has been developed. It is used to assess the profitability and lifetime of the field in light of the dynamics of the geothermal reservoir and varying production profiles. The reservoir dynamics are simulated using a simple lumped parameter model based on physical data. Production can be varied as a function of time and may include stochastic effects to mimic fluctuating market demand. We present some initial work that looks at an analog of the Lauganes geothermal field nearby Reykjavík, Iceland. We make the assumption that the provider must meet market demand, namely that if demand exceeds production for a given number of days, n, pumping capacity must be increased. This criterion is superceded by another that limits the pumping power to a given fraction of the exergy of the geothermal fluid being pumped up. Results show maps of profitability and lifetime under various operating conditions for different values of parameters such as the rate of return, number of days that demand may exceed supply, reservoir size and conductivity.