Greenhouse gas emissions from geothermal powerplants in New Zealand: Is reinjection of gases a solution?

Abstract

The primary purpose of this paper is to discuss the greenhouse gas emissions from geothermal power plants in New Zealand. Geothermal energy has been considered a clean, economical, environmentally friendly, and sustainable source of energy. However, emission from geothermal power plants is a barrier to the growth of geothermal in the present and the future. The emissions have become an issue of primary concern after the report presented by the climate change commission recommending the closing of high greenhouse gas emitting geothermal power plants by 2030. Also, to reach New Zealand targets of achieving net-zero emissions by 2050, the discharge of gases to the atmosphere is to be reduced. The reinjection of separated brine plays an important role in the geothermal system. It provides pressure support that acts as a barrier to cold water recharge and reduces environmental impacts by deposing water back to the reservoir. Reinjection of gases could show different behaviour depending upon the reservoir conditions. This paper gives an outline of the use of geothermal energy for electricity production. It also shows the impact of gases on the flow rate from the well for a single-phase liquid dominated reservoir which showed an increase in flow rate from the well when the gases are present in the reservoir.