Hydrogen Sulfide (H2S) release incidents
Puna Geothermal Venture site, 1998 – 2013  (reported by PGV)

  1. 10 Jan 98    Emergency Steam Release Facility (ESRF) activation during Plant shutdown. 
  2. 10 Jan 98    ESRF activation during plant shutdown due to instrumentation problem.  Plant shutdown and process clearance.
  3. 10 Jan 98    ESRF activation during Plant shutdown.
  4. 5 Feb 98    During start-up, two of the OEC dynamic seals discharged H2S into the atmosphere.
  5. 6 Feb 98    The emergency steam release facility (ESRF) activated, resulting in a discharge of two (2) Klbs of abated steam through the rock mufflers.
  6. 19 Mar 98    The emergency Steam release facility (ESRF) sump pump inadvertently tripped, which resulted in a discharge of steam through the rock mufflers.
  7. 26 May 98    Static Seal leakage during start-up
  8. 11Aug 98    An inadvertent valve failure occurred on the 10" velan isolation valve.  The failure was primarily due to the thermal cooling of the valve while the facility was off-line.
  9. 15 Aug 98    During the plant shut-down, a 2"drain line inadvertently leaked, which resulted in an discharge of H2S to the atmoshpere.
  10. 15 Aug 98    During Plant start-up, several OEC Static seals discharged H2S into the atmosphere.
  11. 17 Nov 98    During our scheduled shut-down to repair the 6" recirculating brine line, several OEC Static seals inadvertently discharged low levels of H2S into the atmosphere.
  12. 24 Apr 99    During our scheduled one (1) day shut-down, a OEC Static seal inadvertently discharged low levels of H2S into the atmosphere.
  13. 26 Apr 99    While securing KS-1A and placing KS-3 Injection Well in service, both safety relief valves simultaneously opened and closed immediately, releasing injectate to the atmosphere.
  14. 26 Apr 99    During an upset condition from two (2) OEC units, the Emergency Steam Release Facility armed but did not activate.  Unfortunately, an automatic control valve leaked steam through the closed valve, causing a small visible vapor from the east rock muffler.
  15. 29 Apr 99    Found two (2) isolation valves inadvertently discharging low levels of H2S into the atmosphere.
  16. 21 Jun 99    Helco’s grid voltage became very unstable, resulting in pressure variations of the injection system.  The injection well KS-4 safety relief valve inadvertently opened, releasing injectate to the atmosphere.
  17. 30 Jun 99    An inadvertent valve packing leak occurred on the KS-9 16" velan isolation valve.  The packing leak was priMar ily due to the thermal cooling of the valve while the facility was off-line.
  18. 3 Jul 99    Injection well KS-4 safety relief valve inadvertently opened, releasing injectate to the atmosphere.
  19. 26 Aug 99    During the KS-4 fill removal operation, an inadvertent release of H2S entrained in nitrogen released to the atmosphere.
  20. 1 Sep 99    During an inadvertent plant trip, the main steam header increased in pressure which activated the Emergency Steam Release Facility. 
  21. 1 Sep 99    During an inadvertent plant trip, the main steam header increased in pressure which activated the Emergency Steam Release Facility. 
  22. 2 Sep 99    During an inadvertent plant trip, the main steam header increased in pressure which activated the Emergency Steam Release Facility. 
  23. 2 Sep 99    During an inadvertent plant trip, the main steam header increased in pressure which activated the Emergency Steam Release Facility. 
  24. 4 Sep 99    During an inadvertent plant trip, the main steam header increased in pressure which activated the Emergency Steam Release Facility.   Less than 1 lb unabated H2S released.
  25. 7 Feb 01    During a Plant upset, KS-11 8" pressure control valve did not shut 100% due to scale build up.  This caused the rupture dics to burst due to high geothermal fluid pressure.  The relief valves closed within less than an estimated 5 minutes.  Unabated geothermal fluids containing H2S was released during this short time span.
  26. 26 Feb 01    During the scheduled shutdown of the facility, the bleed line connecting from the Production wells to the reinjection line inadvertently leaked gas to the atmosphere through a single 16" isolation valve.
  27. 17 Apr 01    H2S emission incident report.  During Plant Start Up, 4 geo-fluid safety relief valves activated, resulting in releasing H2S for approximately 15 seconds.  Approximately 3.1 lbs of unabated H2S released.
  28. 14 Jun 02    H2S emission from condensate piping leak.
  29. 13 Oct 02    Helco A to B bus tie breaker CB 9604 Tripped on Kaumana line, blowing fuses at the substation.  This put PGV in an upset condition. GEC’s 14 & 25 tripped off line and caused rupture discs to burst due to high geothermal fluid pressure.  The relief valves closed within less than an estimated 5 minutes.  Unabated geothermal fluids containing H2S was released during this short time span. There was no steam release noted from the ESRF mufflers.  Estimated about 3.1 lbs of unabated H2S released.
  30. 5 Mar 03    KS-3 relief valve found blowing to atmosphere.
  31. 14 Mar 03    High pressure braided hose on production well KS-5 west leg blew out at fitting.
  32. 26 Jul 03    Leak at NCG Compressor No.1 interstage cooler.  Registered 10 PPM at the interstage cooler.
  33. 25 Aug 05    H2S emission incident during approved well cleanout of KS-6.  Prior to the cleanout, the wellbore of KS-6 was pressurized with nitrogen.  The flow cleanout commenced at 12:40 p.m.  The H2S abatement system (sodium hydroxide and water injection) was placed in operation ~10 minutes prior to flowing the well into the muffler.  PGV estimates that only nitrogen flowed into the muffler for the first 15 minutes or so.  During the transition from nitrogen to geothermal fluids, an unfamiliar, pungent odor was present, but no H2S was detected.  Approximately sixty minutes from the cleanout start time, H2S was detected.
  34. 7 Dec 05    At approximately 8:15 a.m. during a heavy lightning storm, we sustained a lightning strike, which tripped auxiliary equipment off-line.  The most critical was the condensate booster pumps.  All three operating pumps tripped.  This caused condensate to back up at all 9 OECs.  The individual OECs reduced their output as per design control logic.  The reduction in OEC output caused a high steam pressure condition.  Pressure  relief was accomplished by releasing abated steam through the Rock Mufflers at the Emergency Steam Release Facility (ESRF).  Immediate action taken was to shut in all production wells, then get auxiliary equipment back in service.  By the time we were able to get the first condensate pump back in service, 8 of the 9 operating OECs had tripped off-line.  The ESRF activated for less than two minutes and no H2S permit levels were exceeded.  The readings at B station were confirmed to be false due to the air conditioner trip during the lightning strike.
  35. 9 Jan 06    Station alarm at 5.1 ppb
  36. 2  Feb 06   At approximately 2:20 pm during very high winds we experienced a power plant upset. The upset was caused by fallen trees on the Helco transmission lines.  Immediate action was taken to shut in all production wells.  The reduction in OEC output caused a high steam pressure condition.  Pressure relief was accomplished by releasing abated steam through the Rock Mufflers at the Emergency Steam Release Facility (ESRF).  The ESRF activated two times for less than two minutes each time and no H2S permit levels were exceeded.  The readings at B station were confirmed to be false due to the air conditioner trip during the upset.
  37. 4 Apr 06    At approximately 4:00 pm following a scheduled plant shut down and during start up a leak developed on production well secondary isolation valve.  Upon opening a secondary isolation valve on production well KS-6, a leak developed on the stem packing.
  38. 16 May 06    NCG sample point tubing failed (rusted).  Resulted in H2S release for about 15 minutes.
  39. 19 Dec 06    B-Station alarm of 11.4 ppb.  During process clearance of KS-6 East elg.
  40. 2 Aug 07    During normal operation, Production Well KS-6 experienced a rupture disc failure causing the Pressure Safety Valve (PSV) to lift. The PSV reseated automatically within 3 minutes with little to no emissions.
  41. 12 Jan 07    Process clearance of KS-4 wellhead and KS-5 East leg.
  42. 2 Aug 07    While performing process clearance on Production Well KS-5 piping, H2S was detected at PGV’s air monitoring station B.  Upon investigation, the operators on shift found the abatement system to be the source.
  43. 12 Dec 07    Leaking 2" bleed line on KS-6 resulted in 2 minutes of unabated release.
  44. 5 Feb 08    KS-6 East packing failed.
  45. 22 Aug 08    Heat exchanger testing and cooling water creating steam plume.
  46. 31 Dec 08    Verbal notification only.  H2S alarms from A, B & C Stations with peak reading of 17 ppb.
  47. 12 Jan 09    KS-3 relief valve lifted during high injection line pressure.
  48. 1 Mar 10    During process clearance of KS-6 East leg, leak by from 12" Velan exited a 2" drain.
  49. 12 Apr 10    During Plan Shutdown and process clearance, SulfaTreat system momentarily overflowed during steam header process clearance.
  50. 17 Apr 10    H2S during Plant start up from seals.
  51. 8 May 10    The steam/brine release was from leak on the discharge piping of “C” Brine Injection Piping.
  52. 1 Sep 10    The steam release was from the OEC #12 Vaporizer Pressure Safety Valve (PSV) at shutdown. Further review determined it to be a logic problem.  An automatic valve that was to stay shut during a shutdown of an OEC, opened and allowed the vaporizer to over pressurize, thus releasing steam to atmosphere through a PSV.
  53. 17 Oct 10    Plant shutdown for outage work.  Experienced H2S from secured equipment.
  54. 16 Nov 10    Abatement skid leaked.
  55. 17 Nov 10    Experienced a leak on a 1" valve on KS-13.
  56. 3 Dec 10    Experienced leak on inlet to Brine Injection Pump.
  57. 8 May 11    Experienced leak on discharge pipe of "C" reinjection pump.
  58. 25 May 11    480V power supply line short circuit.  Plant trip.  Emergency Steam release Facility for ~6 minutes.
  59. 20 Jul 11    During scheduled Plant Outage, Monitoring Station B recorded elevated H2S levels.  H2S most likely from KS-14 leak by.
  60. 9 Aug 11    One OEC tripped offline.  Resulted in increased steam pressure.  ESRF opened to reduce system pressure.
  61. 19 Sep 11    KS-1A pressure relief valve opened for a brief moment, releasing geothermal fluids to atmosphere.  Suspect valve opening due to water hammer.
  62. 25 Sep 11    During a Plant upset, KS-11 8” pressure control valve did not shut 100% due to scale build up.  This caused rupture discs to burst due to high geothermal fluid pressure.  The relief valves closed within less than an estimated 5 minutes.  Unabated geothermal fluids containing H2S was released during this short time span.
  63. 28 Sep 11    During a scheduled Plant Shutdown,  H2S from various equipment was detected at Monitoring Station A.
  64. 25 Oct 11    Plant tripped off line due to CB-TX1 disconnection.  ESRF activated for 5 minutes.
  65. 8 Nov 11    Plant trip as a result of bad weather, storm and lightning.
  66. 21 Nov 11    One OEC unit tripped.  Resulting in high steam pressure.  ESRF opened for 19 minutes.
  67. 19 Dec 11    During start up of expansion units, a drain valve was open and released brine for about 30 minutes.
  68. 13 Mar 13    Plant trip offline due to HELCO transmission line fault.  Released abated steam through the ESRF for about 15 minutes.