Puna Geothermal Venture

 
The Puna Geothermal Venture (PGV) is a geothermal energy power plant on the island of Hawaii, the largest island in the state of Hawaii. The plant was shut down shortly after the start of the May 2018 lower Puna eruption, and resumed power generation in November, 2020. The eruption had caused lava to flow over a PGV power substation, a warehouse and at least three geothermal wells that had been preventatively quenched and capped when lava fountains erupted nearby, eventually also cutting off-road access.
PGV is the first and only commercially-productive geothermal electrical plant in Hawaii. Constructed on a site adjacent to failed experimental wells drilled and operated by the Hawaii Geothermal Project in the 1970s and 80s, construction on the generating facility began in 1989 and was completed in 1993.
Prior to the shutdown and lava damage, the plant had an installed generating capacity of 38 MW from six production wells and five injection wells along Kīlauea’s East rift zone. Its output was sold to the Hawaiian Electric Industries (also known as HELCO) to supply the island’s electricity customers. The plant had generated up to 10% of the island’s electrical energy at the beginning of 2018.
Power generation was originally planned to restart in late 2019. The plant's owners were projecting a third quarter of 2020 resumption of power generation to the Hawaii Island grid. However, that projection was incorrect, with the plant resuming limited operations in mid-November, 2020.
History.
Early geothermal exploration and development.
The first exploratory geothermal wells in Kapoho were drilled in 1961–62. The effort was spearheaded by wealthy local landowner Richard Lyman following a trip to Japan, where he learned of a project to lay underwater power cables between the country's islands. Upon returning to Hawaii, Lyman promoted geothermal electrical generation in the Puna district, distributed to Oahu and other population centers by underwater electric cables, as a way of developing the then-newly-admitted-state's economy. He found business partners to establish Hawaii Magma Power in 1961 to develop geothermal energy in the region. Several exploratory drills were made before the company determined that there was insufficient geothermal potential, although Lyman claimed to the "Honolulu Advertiser" that the company "had mechanical difficulties and gave up."
Hawaii Geothermal Project.
In the 1970s, the Hawaii Geothermal Project was formed to conduct research funded by federal and state grants. After scientific studies of the geology and geothermal potential of the area were conducted by HGP, a site for the first well was chosen in 1975. Drilling began without environmental impact studies or a period for public input. At the time, the area around the drill site was very rural and undisturbed, but new subdivisions were planned nearby. The well was occasionally allowed to discharge gas and fluid from the borehole, which created a loud noise and release large volumes of toxins and pollutants into the air. By 1976, three subdivisions nearby had been established and were beginning to see an influx of residents, including twelve families that now lived within one mile of the well. The continued noise pollution and toxic gas discharges began to cause concern and opposition from the new, nearby residents. Nonetheless, funds were secured from the federal and state governments to begin the next step of the project: turning the geothermal energy of the well into electricity. Although HELCO was among the stakeholders in the project, they assured their stockholders that they would not invest the company's capital in the project due to the volcanic and seismic risk at the site.
An experimental 3 MW generator was completed in 1981 and remained operational throughout the 1980s. However, families continued to build and move into the nearby subdivisions, resulting in several attempts and a failed lawsuit to stop the noise and pollution generated from the site. Since the site was within a high lava hazard zone, the generator was built on skids and housed in a building which included a crane so that the generator could be removed if lava flows threatened the facility. Additionally, the wellhead was housed in a concrete bunker that could be sealed to prevent lava from damaging the wellhead. Despite the opposition and the operating losses incurred by operating and maintaining the generator, there was enough support to keep the generator operating. In April 1989, county officials raised concerns about the condition of the facility following a minor blowout and considered reviewing and possibly revoking the operating permit for the site. After several additional incidents at the site in 1989, the facility was ordered to be shut down, which occurred on December 11. During its life, the HGP generator produced between 15 and 19 million kilowatt hours of electricity annually.
Puna Geothermal Venture.
In 1980, HELCO requested a proposal for 25 MW of geothermal electricity generation. To answer the request, a joint venture was formed the same year between two of Lyman's companies and two other companies to produce geothermal energy on a parcel of land leased from the Lyman family. The joint venture was renamed Puna Geothermal Venture in 1981. Over the following years, PGV drilled three wells, but all suffered from mechanical failures of their well casings and were unusable for production.
In 1986, PGV secured a contract with HELCO to supply 25 MW of electricity by 1993. PGV promised that they would be using new technology that would result in zero emissions and operate at a drastically lower noise level. In 1989, when the HGP facility was facing growing problems, the PGV proposed facility managed to overcome enough local opposition to be granted a permit from the local planning commission.
The plant has raised some concerns with local residents as a result of occasional toxic emissions. In 1991, well KS-8 suffered a blowout, causing the state to suspend the permits for the plant. In 2016 the plant's owners were found to be in violation of U.S. Environmental Protection Agency standards regarding hydrogen sulfide releases and was fined $76,500 for two incidents in 2013. Additional concerns and opposition to the plant have been raised by Native Hawaiians, who view all forms of volcanic activity as manifestations of the goddess Pele. To the Native Hawaiians who revere Pele, geothermal wells and energy production are a desecration of her body and spirit.
In 2005 during the drilling of the KS-13 well, magma was encountered at a depth of . The borehole had to be redrilled several times as the magma flowed up the borehole, cooling into clear, colorless glass. The magma, at a temperature of approximately 1922 °F (1050 °C), was dacitic—similar to the granitic rock that forms continents—consisting of approximately two-thirds silica, which contrasts with the dark, iron-rich basaltic rock that forms most of the Hawaiian Islands. It was encountered after drilling through a layer of diorite igneous rock, which suggested to researchers that the magma had chemically separated as it dwelled for a long period of time. As quoted in the journal "Nature", the team said it was possibly the first time that "the actual process of differentiation of continental-type rock from primitive ocean basalt has been observed "in situ"". Magma specialist Bruce Marsh of Johns Hopkins University described the uniqueness of the encounter: "Before, all we had to deal with were lava flows; but they are the end of a magma's life. They're lying there on the surface, they've de-gassed. It's not the natural habitat. It's the difference between looking at dinosaur bones in a museum and seeing a real, living dinosaur roaming out in the field."
PGV had a generating capacity of 25 MW when it opened in 1993, which was expanded to 30 MW in 1995 and 38 MW in 2012. In 2015, HELCO announced that Ormat was selected as the winner of a bid to add 25 MW of geothermal generating capacity in the Puna district. In March 2018, Ormat announced their plan to increase production at the plant by 8 MW—from 38 MW to 46 MW—by 2020.
Lava damage and closure in 2018.
On May 3, 2018 earth fissures opened inside and around the Leilani Estates subdivision near the PGV plant, following hundreds of earthquakes over the first two days of May, resulting in concerns of possible toxic hydrogen sulfide gas releases and explosions at the geothermal power facility. According to PGV's vice president of community affairs, PGV began preemptively shutting down equipment and inventorying its stockpile of highly-flammable pentane when the frequency of earthquakes began increasing and the first cracks appeared in Leilani Estates on May 1–2; the plant was taken off-line approximately three hours after it received the first report that lava had begun to emerge from the ground on May 3. All pentane stored at PGV, approximately , was removed by the morning of May 10.
Over the next couple of weeks, the wells were quenched with cold water to stabilize them—where the weight of the cold water was sufficient to prevent steam from rising from the bottom of the well—and allow them to be plugged. One well, KS-14, possibly being super-heated from close proximity to magma, could not be quenched and was filled with a drilling mud in an attempt to stabilize it. The wells were then sealed with metallic plugs, which arrived at the site on May 22, that officials with PGV claim can withstand 2000 °F (1100 °C) lava. According to Tom Travis of the Hawaii Emergency Management Agency, he researched and was unable to find any precedent for lava overrunning a geothermal well that had been shut down like the wells at PGV. The PGV team had spoken with scientists in Iceland that have operated wells within lava fields and provided insights into how lava might affect the wellhead of a shutdown well.
Lava approached several of the capped wells on May 27. Two of the 11 capped geothermal wells, identified as KS-5 and KS-6, were covered by the lava from fissures 7 and 21 on May 27 and 28. The event was the first time lava had covered a geothermal well. On May 30 a substation and a warehouse containing a drilling rig were overrun and destroyed by molten rock, with the main access road to the facility cut. A third well was covered with lava later during the eruption.
Despite the geothermal plant's shutdown, Hawaii Electric Light did not expect blackouts on the Big Island to be caused by insufficient power generation as older, diesel-fueled generators were brought on-line. According to PGV's vice president of community affairs, the wells could be put back into operation.
Projected 2019 reopening delayed, November 2020 restart.
The facility was reported to reopen in late 2019 by first clearing some of the wells quenched during the 2018 eruption. The wells covered by lava have remained untouched. Future plans included the drilling of new wells. Work began on the drilling in late 2019. The plant resumed operations in November 2020.
Kapoho Geothermal Reservoir.
PGV is located in the East Rift Zone of the Kīlauea volcano, which forms the Big Island of Hawaii. The geothermal energy reservoir discovered by the Hawaii Geothermal Project in this location is known as the Kapoho Geothermal Reservoir. The geothermal energy potential of the East Rift Zone is estimated to exceed 200 MW. The geothermal reservoir is contained within basaltic rock and relies on the permeability of two major fracture systems. Both fracture systems have large openings, recorded by the drop of drillbits for up to .
Facilities.
The first and only geothermal energy plant in Hawaii, the plant began generating power in 1993, and is owned by Ormat Technologies which purchased it in 2004.
Power plants.
There are two power plants in the Puna Complex. The first plant consists of ten Combined cycle Ormat Energy Converters (OEC) made up of ten steam turbines and ten binary turbines. Production of electricity began on April 22, 1993. The second plant consists of two Binary cycle OECs and was placed in service in 2011 and commenced commercial operation in 2012. There is a plan to replace the first plant's ten old OECs with two new OECs which increase the generating capacity from 38 MW to 46 MW.
Wells.
As of December 2017, there were six production wells and five injection wells in the Puna Complex.
As of 2008, there are five active production wells all of which have a surface elevation of above sea level and produce a mixture of steam and brine. The five wells produced an average of 600,000 lb/hour (270,000 kg/hour) of steam and 1,200,000 lb/hour (545,000 kg/hour) of brine. The temperature of fluids emerging from the production wells is approximately 640 °F (338 °C), which is returned to the injection wells at approximately 300–400 °F (150–200 °C) after being used to generate electricity.
Alternative uses of geothermally-heated fluids.
In addition to electricity generation, additional uses of the facility have been suggested. A paper presented by Andrea Gill of the Hawaii Department of Business, Economic Development, and Tourism—on behalf of a working group established to consider direct uses of the geothermal energy at PGV and its vicinity—outlined potential direct uses of the fluids at PGV as well as shallow groundwater wells in its vicinity, including fruit and macadamia nut dehydration, aquaculture and greenhouse heating, pasteurization and sterilization, geothermal/health spas, and geothermal heat pumps. At PGV, hot brine after being utilized to generate electricity is approximately 300–400 °F (150–200 °C) when it is reinjected into the earth; the brine could be tapped for its thermal energy before being reinjected. Water wells under 750 ft (230 m) in the vicinity of PGV have recorded temperatures up to 193 °F (89 °C).
In 2005, after a drill hit an uncommonly-observed type of magma, researchers and PGV expressed a desire to turn the borehole into an observatory for scientific studies.