Performance and Cost Discussion

The estimated performance and cost through the year 2030 are presented in Table 1, along with uncertainty estimates of some of the key parameters. The Current and Mature Technology scenarios are represented in the columns for 1997 and 2030. Second Generation Technology is projected for 2015, such that projections in the 2010 and 2020 columns bracket the Second Generation Technology.

The cost of developing HDR geothermal resources is greater than that for hydrothermal binary plants although the technology employed is ess entially the same. This is due to several factors. First, the greater unit cost of the binary power plant for HDR resources is due to scale (hydrothermal binary plant costs are based on a 50 MW plant) . Second, HDR wells are much deeper than typical hydrothermal wells, making them 3 to 5 times more expensive . Finally, the estimated flow rate per HDR well is only about a third of that of a good hydrothermal well, requirin g more wells for a given level of power output.

The performance and cost estimates are based on a number of technical assumptions. The analysis assume s commercial binary power plant technology with dry cooling, similar to that used at numerous hydrothermal site s in the U.S. and elsewhere. The injected water will be heated to the average formation temperature but will los e about 24oC (75oF) by conduction through the well as it travels to the surface. This results in an initial plant inle t temperature of 251oC (484oF) for the geothermal fluid. However, for design conservatism, the plant is designe d for and operated at an inlet temperature of 226oC (439oF).

Based on this temperature, a flow rate of about 224,000 kg per hour is required to support a small power plant, and it is estimated that a reservoir of 98 million m3 will contain sufficient heat to operate the plant for 20, or more, years. These parameters were used at Kansas State University, in GEOCRACK, to simulate the thermodynami c response of the reservoir. GEOCRACK is a discreet element hot dry rock reservoir simulator that accounts for rock deformation, heat transfer, and fluid flow [6]. The results, presented in Figure 4, indicate the timing of the thermal

250-

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

Get My Free Ebook


Post a comment