This spreadsheet is a compilation of Direct Use Geothermal pump system observations (basic description of sites utilizing geothermal energy for space heating, greenhouses and resorts and other direct use applications) compiled by the Massachusetts Geological Survey, published as a Web feature service for the National Geothermal Data System. The document contains 6 worksheets, including information about the template, notes related to revisions of the template, Resource provider information, the data, a field list (data mapping view) and a worksheet with vocabularies for use in populating the spreadsheet (data valid terms). Data from 104 sites utilizing this technology are included. Fields in the data table include FeatureURI, Name, UTM_E, UTM_N, UTMDatumZone, LatDegree, LongDegree, SRS, LocationUncertaintyStatement, LocationUncertaintyCode, LocationUncertaintyRadius, LocationKeyword, HeatApplication, Temperature, TempUnits, TempMeasurementProcedure, TempMeasurementDate, UserType, Flow, FlowUnits, FlowMeasurementProcedure, Capacity, CapacityUnits, CapacityProcedure, EnergyUse, EnergyUseUnits, EnergyUseProcedure, LoadFactor, FacilityContact, PostalAddress, Zip, Phone, EMailAddress, Source, MetadataURI and DataEntrySource.

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.

At the request of the United States Department of Energy, the author was asked by the Geothermal Energy Association (Washington, D.C.) to prepare a white paper on the subject (in connection with a new national assessment of geothermal resources). This paper offers a possible scheme in which geothermal resources are classified into seven categories based on temperature: non-electrical grade (<100°C), verylow temperature (100°C to <150°C), low temperature (150°C to 190°C), moderate temperature (190°C to <230°C), high temperature (230°C to <300°C), ultrahigh temperature (>300°C), and steam fields (approximately 240°C with steam as the only mobile phase). In the first four classes, liquid water is the mobile phase in the reservoir; in the “high” and “ultra-high” temperature reservoirs, the mobile fluid phase is either liquid or a liquid-vapor mixture.

This paper presents an analysis of power generation prospects from Enhanced Geothermal Systems (EGS), specifically, reservoirs with subcommercial permeability enhanced by hydraulic stimulation. EGS is also known as “hot dry rock” or “hot fractured rock” systems. The performance under consideration here is the net electrical power delivered as a function of time over the 20-to-30 year life of a power plant. Although the parameters in this exercise generally reflect conditions encountered at the Desert Peak EGS project in the State of Nevada, United States, the conclusions are applicable, at least qualitatively, to any EGS project.