Advances in binary-cycle power and submersible pump technologies over the past two decades have made electric power generation from geothermal fields in the moderate temperature range (100° to 180°C) convincingly commercial. For geothermal water in this temperature range, binary-cycle is more efficient for power conversion than flash-cycle and pumping of wells is more efficient than self flowing. The lower temperature limit of 100°C is imposed by the limits of binary-cycle technology and the upper limit of 180°C is imposed by the limits of pump technology commercially available today. This paper is a case study of optimization of net power generation from such a field at Raft River, in the State of Idaho, United States.

There are three types of petroleum wells potentially capable of supplying geothermal energy for electric power generation: (a) a producing oil or gas well with a water cut, (b) an oil or gas well abandoned because of a high water cut, and (c) a geopressured brine well with dissolved gas. This paper considers the basic technical and economic aspects of power generations from each of the three types of wells and presents case histories of estimating the available power capacity of a typical well (or a group of wells) in each of the above categories. We have conducted these assessments for commercial developers and operators.