Air-Cooled Condensers for Next Generation Geothermal Power Plants: Final Report.

摘要

This report summarizes the efforts performed under the ARRA project 'Air-Cooled Condensers in Next Generation Conversion Systems'. This project examined technologies that provide near-term improvements to the performance of binary power plants utilizing air-cooled condensers. The motivation for pursuing these improvements is to reduce the power generation costs for enhanced geothermal system (EGS) resources. The study is based on two premises: Water will not be readily available, and there will be no consumptive use of it in the surface energy conversion system; and The EGS resources utilized for power production will be at greater depths, requiring expensive wells to access the heat. In addition, these resources will have costs associated with the creation of the subsurface reservoir where heat that powers the energy conversion system is extracted. The costs associated with the well field development and EGS reservoir creation provide the impetus for using more efficient energy conversion systems, as well as conversion systems that have higher efficiencies at 'off-design' conditions. In identifying the more efficient conversion systems, this work focused on: Existing technologies with the potential to increase conversion efficiency. These are commercially available technologies that are not typically used in plants operating on hydrothermal resources; Design strategies to increase plant output during operation at higher ambient temperatures, as well as at 'off-design' conditions (operation at resource and ambient temperatures other than those for which the plant was designed); and The feasibility of using mixed working fluids in binary plants using air-cooled condensers. Mixtures have been shown to have the potential to increase binary plant performance by 10% to 20%.