Pipe Rupture, Fires Vex Ivanpah Solar Crews | KCET
Pipe Rupture, Fires Vex Ivanpah Solar Crews
The Ivanpah Solar Electric Generating System in the Mojave Desert suffered a setback in mid-May when a rupture was found in a tube intended to heat steam for use generating power at Unit 2. Repairs are still continuing, according to a state agency that monitors the energy plant. That rupture followed close on the heels of three "ignition incidents" at the plant's Units 1 and 2.
One of the small fires stemmed from a scaffolding being inadvertently exposed to the plant's concentrated solar "flux," while the other two resulted from improper use of a flammable adhesive.
The Unit 2 pipeline rupture occurred in Mid-May. Repairs are ongoing at the 392-megawatt facility being built by Bechtel for BrightSource Energy and NRG in the Ivanpah Valley near Primm, NV. As California Energy Commission (CEC) press representative Sandy Louey told ReWire;
May 14, the day before the failure, marked the first time flux had been achieved at Unit 2 -- meaning that enough of the Unit's heliostats had been aimed at the solar receiver steam generator to create the concentrated solar flux. In the words of BrightSource's Ivanpah website;
According to Louey at the CEC, the rupture -- for which project owners have not filed a detailed incident report -- did not occur while the boiler was "on flux." Each of Ivanpah's three units has a natural gas-fired component intended to supplement sunlight in heating up steam for the project's turbines, especiially at dawn or during especially cloudy weather.
The pipeline rupture capped off what must have been a trying couple of weeks for Ivanpah crews. In three separate incidents reported to the CEC over two weeks in April and May, small ignitions were spotted and extinguished at Ivanpah's Units 1 and 2. We'll refer to them as "fires" here for simplicity's sake, but Bechtel's Sonia Taylor points out that the word might give an impression of larger conflagrations. In one incident, some smouldering wood planks were extinguished: in another, non-fireproof adhesive used to affix insulation to pipes "flash-ignited." Bechtel only characterizes one of the incidents as a "fire." None of the incidents cauused injuries or significant property damage.
On Monday, April 29, concentrated solar flux at the plant's Unit 1 ignited a work platform made of wooden planks near the unit's "superheater" section. The superheater section takes already hot steam and exposes it to concentrated solar flux in the unit's solar receiver steam generator, heating it even further before it enters the unit's steam turbines. At about 1:10 in the afternoon, workers noticed smoke coming from near the top of the tower and notified Bechtel safety crews. According to incident documents Bechtel filed with the CEC, the smoke was coming from wood planks that had been exposed to sufficient solar flux that they were smouldering.
Operations at Unit 1 returned to normal wiithin the hour after the wood had been extinguished and discarded. The wood was in place as part of a scaffolding to hold workers as they reinforced wallls in the Superheater section of the power tower. According to the Bechtel report to CEC,
On May 10, pipe insulation adhesive placed by subcontractor Farwest ignited in separate incidents at Unit 1 and Unit 2, both stemming from the use of non-fireproof adhesives by subcontractor Farwest. Both incidents apparently happened during "steam bllow" testing, in which the plants' natural-gas-fired boilers ramped up steam pressure to test the systems' integrity.
The Unit 1 incident was described as a fire by Bechtel observers:
May 10 was a bad day for Farwest, apparently, as its choice of adhesives also contributed to the problem that same evening at Unit 2. According to Bechtel's report on that concurrent incident, a temporary "T" junction in a steam tub left adhesive backing holding insulation on one of the tubes exposed to temperatures of 650°F.
Farwest has been instructed to change its adhesives to more fireproof kinds, and to make sure all temporary junctions are insulated.
All told, a tough spring for Ivanpah. According to Sandy Louey at the CEC, the Commission's staff will be visiting Ivanpah this month to determine whether any of the incidents will affect the agency's approval of the one other solar electric project BrightSource has in the approval pipeline, the Palen Solar Electric Generating System near Joshua Tree National Park in Riverside County. Louey says depending on the results of that visit, the CEC may insist on more detailed "conditions of approval" in order to protect worker safety at Palen.
[Editor's note, July 19: after hearing that some readers were interpreting our earlier headline's reference to a "pipeline rupture" to mean a rupture in a pipe carrying something other than steam, we've edited the headline to help forestall that misinterpretation.]
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