DEPOSITION - THE GEOTHERMAL CONSTRAINT.

The world wide status of geothermal energy developments are reviewed and the opportunities for its utilization emphasized. Several different methods of recovering the energy contained in geothermal fluids are discussed briefly including: total flow systems, district heating, power generation, heat exchangers and desalination. The major obstacle in all applications appears to be the deposition of dissolved solids from the geothermal fluid onto surfaces. A discussion is presented of the relationship between underground and surface conditions on the solubility of dissolved salts and the effects upon utilization of the energy. Experimental work is outlined on the deposition of dissolved minerals from geothermal waters onto surfaces particularly as it affects energy transfer. The fouling of heat exchanger surfaces is shown to follow a linear relationship with time for low velocities. At high flow rates the relationship appears to be asymptotic.