ASSESSING THE VIABILITY OF GEOTHERMAL PROJECTS USING PUMPED WELLS

Abstract

The common assumption within the world of high-temperature geothermal development has been that the economics of geothermal projects producing from resources below 200 ºC are so poor that such resources are generally not considered viable for power production and given a low priority for attention. While a very high tariff in selected locations such as Germany has enabled some deep, low-temperature power projects to be built in the last decade, these projects indeed are high cost mainly due to the depth of wells required to produce from warm aquifer sources in deep sedimentary basins for power. However, a substantial number of projects tapping resources in the 145 to 160 ºC range have been developed in the USA in the last eight years in a relatively low tariff environment and an absence of major subsidies.
Through Jacobs’ work assisting with inventory studies for the government agencies in Indonesia, we have had to look closely at lower temperature systems that surprisingly form the bulk of the new systems now being identified in Indonesia. The accessible, hightemperature systems have primarily been identified and claimed, and these lower temperature systems comprise much of the future pipeline for geothermal exploration. We have had to apply global experience from the low-temperature sector of our industry to analyse the well pumping technology required to achieve economic well production and other key factors that may make these projects surprisingly viable. We share these learnings, and we also suggest some opportunities for the New Zealand geothermal industry to evaluate and possibly adopt this technology.