Ngawha incident – UPDATE 2
Kerikeri, Thursday 27 February 2014 – UPDATE #2 at 1145
Ngawha incident – UPDATE 2 (updates details about pentane release and causes)
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CAPTION: Top Energy CEO Russell Shaw with an activated burst disc, part of the pressure release safety system triggered at Ngawha this morning.
A pressure relief valve at Top Energy’s geothermal electricity generation plant at Ngawha was triggered at around 5.30am today. A pressure safety valve opened as designed, releasing pressure from the system resulting in a loud bang.
The single staff member on overnight duty activated the emergency procedure to automatically shut down the plant and summoned the Fire Service before vacating the site safely. The site contains a total of 30,000 litres of pentane gas.
The Fire Service entered the site and after extensive testing declared it safe at 7.17am.
The site continues to generate 15MW of power.
An investigation into the cause of the pressure build-up is underway. This is being conducted by Top Energy experts.
The pressure build-up occurred in a vaporiser unit which transfers heat from geothermal liquid into the pentane which, in turn, drives the turbines.
A first-stage pressure dump valve which is supposed to release pressure as it builds did not operate as it should have. A secondary safety release valve did operate as designed, creating several loud bangs.
The investigation has so far shown that a relatively small amount of pentane gas was released into the atmosphere.
Top Energy will post any updates on its website, as these become available.
“We are concerned that this incident occurred but delighted that our emergency procedures appear to have worked as they should have,” said chief executive Russell Shaw. “We’re particularly proud of our duty staff member and the local fire service who ensured that this was a textbook response to the incident.”