GEOTHERMAL GREENHOUSE GAS EMISSIONS IN NEW ZEALAND IN 2020: LIFECYCLE AND OPERATIONAL EMISSIONS

Abstract

Greenhouse gas emissions from fourteen New Zealand (NZ) geothermal power stations in the calendar year 2020 are presented in this paper. Source data is given, verified against alternative sources, and used to calculate the overall geothermal emissions intensity for each power station as gCO2e/kWh(net). Statistical analysis of the results gives a representative emissions intensity for NZ geothermal electricity generation overall for 2020. Comparison of this to previous years shows a continuing decline in emissions intensity.
The emissions intensities presented in this paper are operational emissions only, those that are released directly during the operational phase of the plant life. This, however, only represents one portion of the total emissions over the full lifecycle of the plant. Life cycle analysis (LCA) “lifecycle emissions” take account of all emissions over the full life cycle of the plant, including materials and construction, operation and maintenance, and decommissioning. Accounting for the full life cycle will increase geothermal emissions intensity above the operational emissions by 20% on average for the NZ stations. Statistical comparison to life
cycle emissions from other energy sources shows that NZ geothermal has the highest emissions intensity of the renewables, followed by solar PV, concentrating solar, hydro and then wind with the lowest. All renewables have life cycle emissions, an order of magnitude less than fossil fuel energy sources.