This paper investigates the constrained double-flash geothermal power plant design space across a range of brine and condenser temperatures. Silica deposition and/or turbine exhaust quality constraints reduce specific work output at most brine temperatures. Some combinations of brine temperature and condenser temperature are also shown to be infeasible. Reducing condenser temperature is shown to improve specific work output up to 47% with diminishing effect as brine temperature increases. Relaxing the silica constraint is shown to yield up to an 8% increase in specific work output. These results are useful to a plant designer in determining the value of installing improved condensing or silica control equipment. (c) 2013 Elsevier Ltd. All rights reserved,