Improved Energy Utilization in the Cerro Prieto Geothermal Field Fluid Transportation Network

Abstract

The thermal performance and the potential for improving energy utilization at the Cerro Prieto geothermal field (CPGF) were evaluated. The study is based on the premise of no additional producing wells and includes the fluid transportation network only. For the evaluation of the transportation network performance, the mass, energy and exergy flows of the separated steam and water at selected points of the transportation network, the mass and heat losses from the separators, pipelines and fittings, and the partial (transportation sub-processes) and overall (wellhead to power plant inlet) thermal efficiencies were evaluated. The 1st law efficiencies range from 86.8 to 98.1% for the individual fluid transportation sub-processes while those of the 2nd law vary from 78.9 to 95.9%. The overall efficiencies are 67.6% and 75.2%, respectively. The potential for improvement of energy utilization involved the evaluation six areas of opportunity. Four of them involve diverse schemes for energy recovery in the steam transportation pipeline network, one for energy recovery from the separated water, and the other involves reducing heat losses from the pipelines and fittings. The analysis shows a potential for installing 71.6 MWe of additional power which represents an increase of 9.9 % over the field installed capacity of 720 MWe. In addition, it is possible to gain an equivalent of 11.2 MWe by reducing heat losses from the steam transportation pipeline networks and fittings. Hence, by maintaining the same rate of fluid and energy extraction and the same number of producing wells, it is possible to increase the field energy utilization by 82.82 MWe or 11.5 % of the present installed capacity.