Comparative Analysis of Alternative Means for Removing Noncondensable Gases from Flashed-Steam Geothermal Power Plants:April 1999 - March 2000

This dataset corresponds to the final report on a screening study to compare six methods of removing noncondensable gases from direct-use geo-thermal steam power plants. This report defines the study methodologies and compares the performance and economics of selected gas-removal systems. Recommendations are presented for follow-up investigations and implementation of some of the technologies discussed. The specific gas-removal methods include five vacuum system configurations using the conventional approach of evacuating gas/vapor mixtures from the power plant condenser system and a system for physical separation of steam and gases upstream of the power turbine. The study focused on flashed-steam applications, but the results apply equally well to flashed-steam and dry-steam geothermal power plant configurations. Two gas-removal options appear to offer profitable economic potential. The hybrid vacuum system configurations and the reboiler process yield positive net present value results over wide-ranging gas concentrations. The hybrid options look favorable for both low-temperature and high-temperature resource applications. The reboiler looks profitable for low-temperature resource applications for gas levels above about 20,000 parts per million by volume. A vacuum system configuration using a three-stage turbocompressor battery may be profitable for low-temperature resources, but results show that the hybrid system is more profitable. The biphase eductor alternative cannot be recommended for commercialization at this time.
The report is available from NREL's publication database.