Geothermal plant

A very sueeessful projeet began in the early 1980s when the Ben Holt Company (Pasadena, California) designed and eonstrueted a 10 MW air-eooled, elosed-loop binary eyele at their Mammoth Geothermal Plant, loeated on the eastern slope of the Sierra Nevada mountain range in California. 

Figure 4-43. Typical binary cycle used in geothermal plants.

The eost of produeing power varies with the eapaeity and temperature of geothermal brine and the eooling method seleeted. For illustration purposes, the estimate of the installed eost of a binary eyele geothermal plant is l,500/kW -i- 250,000. Using an average revenue of 0.07 per kW/hr, a 1 MW geothermal plant will have a three-year paybaek period. 

Armannsson, H. 2003. C02 emission from geothermal plants. In Proceedings of International Conference on Multiple Integrated Uses of Geothermal Resources, Reykjavik, 14-17 September, S12, 56-62. 

Ballzus, C., Frimannsson, H., Gubbarsson, G. I. Hrolfsson, I. 2000a. The geothermal plant at Nesjavellir, Iceland. In Proceedings World Geothermal Congress 2000, Kyushu-Tohoku, Japan, 28 May-10 June 2000, 3109-3114. 

Sanopoulos, D. Karabelas, A. 1997. H2S abatement in geothermal plants Evaluation of process alternatives. Energy Resources, 19, 63-77. 

Villa, F. P. 1975. Geothermal plants in Italy Their evolution and problems. In Proceedings Second United Nations Symposium on the Development and Use of Geothermal Resources, San Francisco, 20-29 May 1975, 2061-2064. 

Geothermal Plant A plant in which the prime mover is a steam turbine. The turbine is driven either by steam produced from hot water or by natural steam that derives its energy from heat found in rocks or fluids at various depths beneath the surface of the earth. The energy is extracted by drilling and/or pumping. 

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Renewable energy resources have special attractive attributes. Renewable resources are more modular, even when developed in a centralized situation. Most biomass and geothermal plants are less than 100 MW. Wind turbines are physically separated and thus stand as separate risks. Fifty MW of wind turbines in one wind farm cover a large area. The loss of a single turbine has minimal impact on the system, and there is no fuel supply delivery system risk. 

In this demonstration plant, the boiler feedwater can be preheated by geothermal heat if available. Depending on the availability and temperature of the geothermal heat in the area, the geothermal plant s design would vary. If the groundwater temperature exceeds 150°C (302°F), a "flash steam" power plant would be used, and if it is between 100 and 150°C (212 and 302°F), a "binary cycle" power plant would be used. 

Baldi F. 1988. Mercury pollution in the soil and mosses around a geothermal plant. Water Air Soil Pollut 38(1-2) 111-119. 

High availability and reliability— Availability is defined as the percentage of time that a system is capable of producing electricity. Availability of 95-99% is typical for modern geothermal plants compared to maximum 80-85% for coal and nuclear plants. ... 

Many geothermal plants generate no appreciable waste... 

Environmental problems can also be present when renewable sources of energy are used. Condensed steam from geothermal plants may have to be cleaned up before it can be discharged. Reinjection into the reservoir avoids this problems. Hydropower requires dams that remove the niches in running streams that foster biodiversity. Cool, well-aerated running water favors different species more than lakes do. A shaded stream can have a different flora and fauna that may be more diverse than that in the sunny lake behind the dam. The dams also interfere with the... 

As far as geothermal energy is concerned, geothermal plants can release CO2 during operation. The emissions vary greatly from plant to plant and the reported range is from 0 to 400 g COj-eq/kWh (Pehnt, 2006 Moriarty and Honnery, 2007). 

Binary Cycle Geothermal Plants - Binary cycle systems can be used with liquids at temperatures less than 350 F (177 C). In these systems, the hot geothermal liquid vaporizes a secondary working fluid, which then drives a turbine. 

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