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Title: Advanced binary geothermal power plants: Limits of performance

Technical Report ·
DOI:https://doi.org/10.2172/5982472· OSTI ID:5982472

The Heat Cycle Research Program is investigating potential improvements to power cycles utilizing moderate temperature geothermal resources to produce electrical power. Investigations have specifically examined Rankine cycle binary power systems. Binary Rankine cycles are more efficient than the flash steam cycles at moderate resource temperature, achieving a higher net brine effectiveness. At resource conditions similar to those at the Heber binary plant, it has been shown that mixtures of saturated hydrocarbons (alkanes) or halogenated hydrocarbons operating in a supercritical Rankine cycle gave improved performance over Rankine cycles with the pure working fluids executing single or dual boiling cycles or supercritical cycles. Recently, other types of cycles have been proposed for binary geothermal service. This report explores the feasible limits on efficiency of a plant given practical limits on equipment performance and discusses the methods used in these advanced concept plants to achieve the maximum possible efficiency. (Here feasible is intended to mean reasonably achievable and not cost-effective.) No direct economic analysis has been made because of the sensitivity of economic results to site specific input. The limit of performance of three advanced plants were considered in this report. The performance predictions were taken from the developers of each concept. The advanced plants considered appear to be approaching the feasible limit of performance. Ultimately, the plant designer must weigh the advantages and disadvantages of the the different cycles to find the best plant for a given service. In addition, this report presents a standard of comparison of the work which has been done in the Heat Cycle Research Program and in the industrial sector by Exergy, Inc. and Polythermal Technologies. 18 refs., 16 figs., 1 tab.

Research Organization:
EG and G Idaho, Inc., Idaho Falls, ID (United States)
Sponsoring Organization:
USDOE; USDOE, Washington, DC (USA)
DOE Contract Number:
AC07-76ID01570
OSTI ID:
5982472
Report Number(s):
EGG-EP-9207; ON: DE91010065
Country of Publication:
United States
Language:
English