PRODUCTIVE AND ALLOCATIVE EFFICIENCY - ROTORUA GEOTHERMAL SYSTEM

Abstract

The Rotorua Geothermal System is managed under the Rotorua Geothermal Regional Plan (1999), to protect its rare and vulnerable surface features. The current plan has strong imperatives to support efficiency in the use and allocation of the geothermal resource.
The effectiveness of these policies, and their implementation, has been assessed as part of a review of the regional plan. This work identified the typical efficiency issues in the geothermal production and distribution systems in Rotorua, and at the user end. To
improve efficiency in allocation, the Bay of Plenty Regional Council is developing a robust process and an allocation App to calculate the heat and mass (geothermal fluid) load for benchmarking efficient use and allocation of the resource. There are limited suitable
methods or technologies for accurate and continuous measurement of the geothermal fluid take in Rotorua due to its unique settings (i.e. geothermal fluid properties, mixed use and shared schemes, and environmental and regulatory constraints). Those challenges were overcome with the development of a movable flow loop, and trials showed that over 50% of the users may be using less than 30% of their allocated geothermal fluid. Increasing certainty around the actual heat and mass production from the system will reduce the risk of over-allocation while making better use of the estimated sustainable resource available. Wasteful practices are expected to be minimised mostly through allocation for efficient use coupled with tighter take monitoring. Most importantly, improved allocation and use will contribute to the sustainable management of the resource and protection of its unique surface features.