Economic optimization of enhanced geothermal systems using a fully analytical temperature profile

ABSTRACT In enhanced geothermal systems (EGS), the efficiency of the energy recovery process is highly dependent on the produced fluid’s temperature. In this work, a new analytical scheme is proposed for predicting the spatiotemporal evolution of temperature profile based on the three-dimensional energy conservation equation solved on the vertical plane passing through the wells. The solution is given in an error-function form which suits well for feasibility studies. An economic study is then conducted on the cost of operation based on the analytically described temperature and pressure distribution. The cumulative gain of operation, including the cost of pumping and reduced gain due to thermal breakthrough, is optimized with respect to the well spacing and the water injection rate. Optimum well spacing – injection rate combinations have been obtained for varied project life times. The maximum cumulative gain calculated by this method can be used for capex analyses and project lifetime predictions.