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Title: Economic impact of corrosion and scaling problems in geothermal energy systems

Abstract

Corrosion and scaling problems have a significant impact on geothermal plant economics. A power plant must amortize the capital investment over a 20-year period and achieve satisfactory operating efficiency to achieve financial success. Corrosion and scale incrustations have been encountered in all geothermal plants, and to various degrees, adversely affected plant life times and power output. Using published data this report analyzes known geothermal corrosion and scaling phenomena for significant cost impacts on plant design and operation. It has been necessary to speculate about causes and mechanisms in order to estimate impacts on conceptual geothermal plants. Silica is highly soluble in hot geothermal water and solubility decreases as water is cooled in a geothermal power plant. Calculations indicate as much as 30,000 tons/year could pass through a 100 MWe water cycle plant. The major cost impact will be on the reinjection well system where costs of 1 to 10 mills/kwhr of power produced could accrue to waste handling alone. On the other hand, steam cycle geothermal plants have a definite advantage in that significant silica problems will probably only occur in hot dry rock concepts, where steam above 250 C is produced. Calculation methods are given for estimating the requiredmore » size and cost impact of a silica filtration plant and for sizing scrubbers. The choice of materials is significantly affected by the pH of the geothermal water, temperature, chloride, and H{sub s} contents. Plant concepts which attempt to handle acid waters above 180 C will be forced to use expensive corrosion resistant alloys or develop specialized materials. On the other hand, handling steam up to 500 C, and pH 9 water up to 180 C appears feasible using nominal cost steels, typical of today's geothermal plants. A number of factors affecting plant or component availability have been identified. The most significant is a corrosion fatigue problem in geothermal turbines at the Geyser's geothermal plant which is presently reducing plant output by about 10%. This is equivalent to over $3 million per year in increased oil consumption to replace the power. In the course of assessing the cost implications of corrosion and scaling problems, a number of areas of technological uncertainty were identified which should be considered in R and D planning in support of geothermal energy. Materials development with both laboratory and field testing will be necessary. The economic analysis on which this report is based was done in support of an AEC Division of Applied Technology program to assess the factors affecting geothermal plant economics. The results of this report are to be used to develop computer models of overall plant economics, of which corrosion and scaling problems are only a part. The translation of the economic analysis to the report which appears here, was done on AEC Special Studies Funds.« less

Authors:
Publication Date:
Research Org.:
Battelle Pacific Northwest Labs., Richland, Wash. (US)
Sponsoring Org.:
Not Available (US)
OSTI Identifier:
5122645
Report Number(s):
BNWL-1866
TRN: US200508%%62
DOE Contract Number:  
AT(45-1)-1830
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Jan 1975
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 15 GEOTHERMAL ENERGY; 29 ENERGY PLANNING, POLICY AND ECONOMY; CALCULATION METHODS; CORROSION FATIGUE; ECONOMIC ANALYSIS; ECONOMIC IMPACT; GEOTHERMAL ENERGY; SCRUBBERS; SILICA; ALUMINIUM ALLOYS; CORROSION; CALCIUM CARBONATES; DEPOSITION; CARBON STEELS; COPPER ALLOYS; GEOTHERMAL POWER PLANTS; SCALING; GEYSERS GEOTHERMAL FIELD; NICKEL ALLOYS; SILICON OXIDES; STAINLESS STEELS; TITANIUM; ZIRCONIUM; CORROSION RESISTANT ALLOYS; CORROSIVE EFFECTS; EQUIPMENT; GEOTHERMAL FLUIDS; INJECTION WELLS; TURBINES; ALKALINE EARTH METAL COMPOUNDS; CALCIUM COMPOUNDS; CARBON COMPOUNDS; CHALCOGENIDES; CHEMICAL REACTIONS; CHROMIUM ALLOYS; ELEMENTS; GEOTHERMAL FIELDS; IRON BASE ALLOYS; OXYGEN COMPOUNDS; SILICON COMPOUNDS; GEOTHERMAL LEGACY; 150903* - Geothermal Engineering- Corrosion, Scaling & Materials Development

Citation Formats

Shannon, D W. Economic impact of corrosion and scaling problems in geothermal energy systems. United States: N. p., 1975. Web. doi:10.2172/5122645.
Shannon, D W. Economic impact of corrosion and scaling problems in geothermal energy systems. United States. https://doi.org/10.2172/5122645
Shannon, D W. Wed . "Economic impact of corrosion and scaling problems in geothermal energy systems". United States. https://doi.org/10.2172/5122645. https://www.osti.gov/servlets/purl/5122645.
@article{osti_5122645,
title = {Economic impact of corrosion and scaling problems in geothermal energy systems},
author = {Shannon, D W},
abstractNote = {Corrosion and scaling problems have a significant impact on geothermal plant economics. A power plant must amortize the capital investment over a 20-year period and achieve satisfactory operating efficiency to achieve financial success. Corrosion and scale incrustations have been encountered in all geothermal plants, and to various degrees, adversely affected plant life times and power output. Using published data this report analyzes known geothermal corrosion and scaling phenomena for significant cost impacts on plant design and operation. It has been necessary to speculate about causes and mechanisms in order to estimate impacts on conceptual geothermal plants. Silica is highly soluble in hot geothermal water and solubility decreases as water is cooled in a geothermal power plant. Calculations indicate as much as 30,000 tons/year could pass through a 100 MWe water cycle plant. The major cost impact will be on the reinjection well system where costs of 1 to 10 mills/kwhr of power produced could accrue to waste handling alone. On the other hand, steam cycle geothermal plants have a definite advantage in that significant silica problems will probably only occur in hot dry rock concepts, where steam above 250 C is produced. Calculation methods are given for estimating the required size and cost impact of a silica filtration plant and for sizing scrubbers. The choice of materials is significantly affected by the pH of the geothermal water, temperature, chloride, and H{sub s} contents. Plant concepts which attempt to handle acid waters above 180 C will be forced to use expensive corrosion resistant alloys or develop specialized materials. On the other hand, handling steam up to 500 C, and pH 9 water up to 180 C appears feasible using nominal cost steels, typical of today's geothermal plants. A number of factors affecting plant or component availability have been identified. The most significant is a corrosion fatigue problem in geothermal turbines at the Geyser's geothermal plant which is presently reducing plant output by about 10%. This is equivalent to over $3 million per year in increased oil consumption to replace the power. In the course of assessing the cost implications of corrosion and scaling problems, a number of areas of technological uncertainty were identified which should be considered in R and D planning in support of geothermal energy. Materials development with both laboratory and field testing will be necessary. The economic analysis on which this report is based was done in support of an AEC Division of Applied Technology program to assess the factors affecting geothermal plant economics. The results of this report are to be used to develop computer models of overall plant economics, of which corrosion and scaling problems are only a part. The translation of the economic analysis to the report which appears here, was done on AEC Special Studies Funds.},
doi = {10.2172/5122645},
url = {https://www.osti.gov/biblio/5122645}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1975},
month = {1}
}