| Title | PASSIVE NCG REINJECTION AT TE HUKA GEOTHERMAL BINARY POWER PLANT |
|---|---|
| Authors | N.C. Ruiz, K. McLean, I. Richardson, T. Misa, A. Ferguson, D.E. Altar, and E. Kaya |
| Year | 2021 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | |
| Abstract | Te Huka power plant is part of the Tauhara geothermal field in Taupo New Zealand. This 24 MWe binary plant started operation in July 2010. With 2 production wells and 2 injection wells it has produced around 209 GWh of electricity per year. As is the case for all geothermal reservoirs, Non-Condensable Gases (NCGs - CO2, CH4 and H2S) are naturally occurring in the hot geothermal fluids underground and are released in gaseous form during the power generation process. However not all NCGs are released at Te Huka (and many other binary stations) - due to the relatively high pressure at which the geothermal steam is condensed. Approximately 18.8 % of NCGs are dissolved in the geothermal condensate, which is combined with the separated geothermal water and reinjected back into the reservoir where it came from. We refer to this process as “passive” NCG reinjection – where “active” NCG reinjection refers to an additional process of actively redirecting the NCG gas stream at the surface and dissolving those gases back into the geothermal fluid in the reinjection line. This paper discusses the reinjection history at Te Huka and the effect of NCG reinjection on mineral precipitation and dissolution at the reinjection well feed zones. Reactive transport modelling with TOUGHREACT has been used to compare passive NCG reinjection to active reinjection. The modelling results are used to illustrate the advantages of passive and active NCG reinjection at Te Huka. |