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New geothermal site identification and qualification. Final report

Description: This study identifies remaining undeveloped geothermal resources in California and western Nevada, and it estimates the development costs of each. It has relied on public-domain information and such additional data as geothermal developers have chosen to make available. Reserve estimation has been performed by volumetric analysis with a probabilistic approach to uncertain input parameters. Incremental geothermal reserves in the California/Nevada study area have a minimum value of 2,800 grosss MW and a most-likely value of 4,300 gross MW. For the state of California alone, these values are 2,000 and 3,000 gross MW, respectively. These estimates may be conservative to the extent that they do not take into account resources about which little or no public-domain information is available. The average capital cost of incremental generation capacity is estimated to average $3,100/kW for the California/Nevada study area, and $2,950/kW for the state of California alone. These cost estimates include exploration, confirmation drilling, development drilling, plant construction, and transmission-line costs. For the purposes of this study, a capital cost of $2,400/kW is considered competitive with other renewable resources. The amount of incremental geothermal capacity available at or below $2,400/kW is about 1,700 gross MW for the California/Nevada study area, and the same amount (within 50-MW rounding) for the state of California alone. The capital cost estimates are only approximate, because each developer would bring its own experience, bias, and opportunities to the development process. Nonetheless, the overall costs per project estimated in this study are believed to be reasonable.
Date: April 1, 2004
Partner: UNT Libraries Government Documents Department

Prediction and prevention of silica scaling at low levels of oversaturation: Case studies, and calculations for Uenotai Geothermal Field, Akita Prefecture, Japan

Description: Production system design studies often include site-specific silica scaling field experiments, conducted because the onset and rate of scaling are believed difficult to predict, particularly at relatively low levels of oversaturation such as may exist in separators, flowlines, and injection wells. However, observed scaling occurrences (Cerro Prieto, Dixie Valley, Svartsengi, Otake, Hatchobaru, Milos, experimental work) actually conform fairly well to existing theory and rate equations. It should be possible to predict low level scaling with sufficient confidence for production and injection system design and, in cases where oversaturation is allowed, to design systems with foresight to suppress or manage the scale which develops. A promising suppression technology is fluid pH reduction by mixing with non-condensible gases and/or condensate. Calculations for injection lines at Uenotai geothermal field indicate molecular deposition at rates of 0.1 to 1 mm/yr, and some potential for particle deposition at points of turbulence, which can be suppressed by an order of magnitude with about 500 ppm CO{sub 2}. Further improvements of predictive technique will benefit from more uniformity in designing experiments, reporting results, and reporting measurements of scaling in actual production systems.
Date: January 1, 1991
Creator: Klein, Christopher W.; Iwata, Shun; Takeuchi, Rituo & Naka, Tohsaku
Partner: UNT Libraries Government Documents Department