The 100 kW plant is a direct contact boiling/direct contact condensing binary system using isopentane as the working fluid. Treated waste geothermal brine from the Great Lakes Chemical Co. (GLC) bromine recovery operation is the heat source. Brine is taken from the GLC Treated Brine Line at 205 to 210/sup 0/F and supplied to the pilot plant via the APL Brine Inlet Line. The brine enters the direct contact boiler (DCB) and vaporizes isopentane. The cooled brine is discharged into the reinjection pond at 135 to 155/sup 0/F. The brine flow rate is 45,655 to 87,030 lb(m)/hr (pounds mass per hour). The chemistry of the brine is discussed. The objectives here are to: (1) evaluate present pilot plant materials selections, (2) identify potential materials problems, and (3) recommend alternate materials for use in future systems. (MHR)