Technology Assumptions and Issues

Geothermal (hydrothermal) electric technology is commercially available. The systems characterized here reflec t ordinary conditions and technology for representative high-temperature (232°C/450°F) and moderate-temperature (166°C/330°F) hydrothermal reservoirs in the United States. Technologies for exploration, drilling, and reservoi r analysis and management are essentially the same for the two types of systems. These systems represent condition s and technology that are similar to a High-Temperature system at Dixie Valley, NV (using dual-flash conversio n technology today) and a Moderate Temperature system at Steamboat Hot Springs, NV (using Organic Rankine Cycle, i.e., "binary," technology today). The conditions and technologies selected for this TC broadly represent many aspects of commercial technologies for producing electricity from these resources [1].

Substantial room for improvement exists in most aspects of this technology, including both the fluid-productio n (exploration, wells, and reservoir management) and electricity-conversion (power plant) components. The cost of deep geothermal wells is expected to decline by about 20 percent in 5 to 10 years, mainly through improvements in drill bits. The cost of conversion technologies (power plants) should continue to decrease substantially over the next 5 to 15 years for lower-temperature systems (binary-like), but may not decrease much for higher-temperature (flash) systems because of recent very large reductions in the cost of those systems. The current main thrusts for reducing power plant cost s are: (a) substantial changes in the basic conversion cycle designs used in the plants, including the addition of "topping" cycles and "bottoming" cycles, improved working fluids, and the use of various hybrid cycles that merge the bes t features of flash and binary plants (e.g., see [1]); (b) urgent efforts on the part of owners of geothermal power systems to reduce O&M costs, especially by reducing the number of staff employed at each system and site, in anticipation o f marked reduction in revenues when prices fall under certain contracts [16]; and (c) gradual reduction in comple x instrumentation and controls as engineers learn what is safe to omit.

These improvements are expected to be relatively continual over the next 20 years, due to the combined effects of : (a) industry experience and learning from designing and installing these systems where they continue to be economi c and (b) continuing R&D by the U.S., Japan, Italy, and other nations. In the U.S., the R&D effort is led by the Office of Geothermal Technologies, Office of Utility Technologies, Department of Energy, which has supported an activ e geothermal R&D program since 1974.

As detailed more in Section 4.0, it is believed that continued R&D would be valuable on many fronts, including : (a) development of geophysical methods to detect fluid-filled permeable fractures during exploration and siting o f production wells; (b) substantial decreases in the cost of drilling geothermal wells; (c) moderate decreases in the cost of power plants, and moderate increases in the conversion effectiveness of plants sited on lower-temperature reservoirs; and (d) continuing decreases in the operation and maintenance costs of wells, field equipment, and power plants.

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.

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