In Hawaii, lava continues its creep onto grounds of geothermal power plant

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  • A map of lava from Saturday May 26 at 3pm. US Geological Survey
  • From USGS: “An aerial view, looking west, of the two active ocean entries on Kīlauea Volcano‘s lower East Rift Zone. The large white plume (foreground) is the eastern ocean entry; the weaker, western plume can be seen in the distance. The white plume, referred to as ‘laze,‘ is a mixture of condensed acidic steam, hydrochloric acid gas, and tiny shards of volcanic glass that can irritate lungs, eyes and skin.
  • From USGS: “This ‘a‘ā flow, erupted from fissures 7 and 21, was approximately 3–4 meters (yards) high at the flow front and slowly advancing to the northeast in the Leilani Estates subdivision around 10:30 a.m. HST” on Saturday.

Hawaii‘s Mount Kīlauea eruptions have caused damage throughout the Island of Hawai‘i, but a new concern has been slowly building: earlier this week Reuters reported that  the property of a 38 MW geothermal plant called Puna Geothermal Ventures (PGV). Lava damage could cause problems for the plant‘s operations in the future, and some officials are concerned that damage to geothermal wells could result in releases of hydrogen sulfide gas, which is toxic to humans. Although lava had been held back by a natural berm for days, yesterday that a new lava flow had entered the 815-acre PGV property.

Further Reading

Thus far, the only structure that has been destroyed at the geothermal plant has been an old warehouse that was used in the early days of the plant and had been used for storage since, according to a .

Geothermal power, which uses the natural heat of underground rocks to create electricity, is a low-carbon way to generate a relatively constant supply of electricity. However, no modern geothermal plant has suffered lava damage, Reuters notes, so there‘s no precedent for this situation.

The first fissure to enter PGV property earlier this week, Fissure 6, is 200 to 300 yards from one of PGV‘s 11 geothermal wells. The new fissure that entered PGV property on Saturday night is Fissure 21. In a tweet Sunday morning, the that “Fissure 21 continues a slow advance eastward on PGV property.”  (For a detailed look at why the volcano has been erupting the way it has, .)

In a 6 am update on Sunday morning, The County of Hawai‘i saying, “The Hawaiian Volcano Observatory reports the lava flow in Leilani Estates has crossed into PGV property overnight.  County, State and Federal agencies continue to monitor Hydrogen Sulfide levels and no Hydrogen Sulfide has been detected.”

PGV usually is able to provide about 25 percent of the big island‘s power, but the plant was taken offline after the first eruption of Mount Kilauea. Hawai‘i Electric Light, the power provider for Hawai‘i Island,  for the rest of the island due to PGV‘s downtime because Hawai‘i‘s grid had sufficient backup generation.

Further Reading

After the plant was taken offline in early May, about 60,000 gallons of pentane, a highly-flammable chemical, were moved from the site. Pentane is often used as a “working fluid” for geothermal plants—it has a lower boiling point than water so it heats up quickly when it‘s near water from a geothermal well, and the and then be recirculated.

Despite the removal of the pentane, danger remains if the lava reaches the wells. Geothermal wells often release small amounts of toxic hydrogen sulfide during the course of normal operations, usually well . But lava could destabilize a well and release more.

The best case scenario is that the lava continues to bypass the plant. Ormat, the company that owns PGV, told Reuters that it won‘t be able to asses any potential underground damage to the wells (from lava or the periodic earthquakes that come with it) until the situation stabilizes.

Since last week, workers have been attempting to de-pressurize the wells by pouring thousands of gallons of cold water into them. One well was not able to depressurize, so it was sealed with a mud-like substance, the AP wrote. The wells are each 6,000 to 8,000 ft deep.

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