Preliminary Considerations for Extraction of Thermal Energy from Magma

Abstract

Simplified mathematical models are developed to describe the extraction of thermal energy from magma based on the concept of a counterflow heat exchanger inserted into the magma body. Analytical solutions are used to investigate the influence of the basic variable on electric power production. Calculations confirm that the proper flow path for the working fluid is down the annulus with hot fluid returning to the surface through the central core. The core must be insulted from the annulus to achieve acceptable wellhead temperatures, but his insulation thickness can be quite small. The insulation is effective in maintaining the colder annular fluid below expected formation temperatures so that a net heat gain from the formation above a magma body is predicted. the analyses show that optimum flow rates exist that maximize electric power production. These optimum flow rates are functions of the heat transfer coefficients that describe thermal energy extraction from the magma.