Workers takeBy Helen Altonn
first steps to plug
Site work is under way to prepare for a drill rig to plug and abandon an experimental well on the Big Island that proved the commercial viability of geothermal energy in the 1980s.
The HGP-A geothermal well, drilled in Puna in the late 1970s, was the first to produce geothermal energy in Hawaii.
An experimental generator was installed to find out if that would work, said Thomas Daniel, scientific and technical director, National Energy Laboratory of Hawaii Authority.
"It worked so well, we kept it going quite a bit past its design lifetime," Daniel said.
The well produced up to 3 megawatts of electricity for Big Island residents from 1981-89. Several small businesses also used hot steam from the well as part of the Hawaii Geothermal Community Technology Program in the late 1980s.
Though designed to last only a couple of years, it continued eight years until 1989, when the electric generation system was shut down, Daniel said.
It was temporarily plugged in 1992.
"There has been a big debate about what was necessary to 'plug and abandon' it," he said.
The laboratory's board of directors, which has several geothermal experts, determined the type of plugging needed to conform with rules and regulations and be safe, he said.
Daniel said the well "is very stable right now. It's filled with water, and water quenches the well. As long as you monitor it, it could last forever that way."
But someone would have to monitor it to make sure it doesn't bubble out, he said.
"To live up to the law and to be very safe," he said, "basically we'll pour concrete down the well and fill it up like the rock that was there before."
A drill rig will be moved to the site next week. A fairly big drill rig is required because it has to drill through the temporary plug in the well, more than 6,000 feet deep, Daniel said.
Concrete will be poured from the bottom of the hole to a depth of 3,000 feet to isolate the geothermal production zone.
Then from the 3,000-foot depth to the surface, concrete plugs will be interspersed with heavy drill fluid to prevent geothermal fluids from moving to the surface.
The site will be returned to its original condition in June and turned back to the state Department of Land and Natural Resources, Daniel said, noting the county has expressed interest in the land.
Puna Geothermal Venture has provided about 25 percent of the island's power since 1993. An expansion plan has run into environmental regulations.
Opponents have tried to close the company's 30-megawatt plant, citing air quality problems.