A major test of geothermal energy at The Geysers as a significant alternative to fossil fuels has fallen seriously behind schedule, several federal scientists said this week, even as the project is under review because of the earthquakes it could generate.
Intended to extract heat from hot bedrock, the project has been delayed because the bit on a giant rig, meant to drill more than 2 miles underground, has struggled to pierce surface rock formations, the scientists said.
The bit has snapped off at least once and become repeatedly fouled in a shallow formation called cap rock, and the drillers have twice been forced to pull it out and essentially start the hole over again.
Late last year, the project, undertaken by a startup company called AltaRock Energy, received $6.25 million in financing from the Energy Department, in hopes it would be the first of dozens of projects to produce renewable energy by fracturing rock at the bottom of a deep hole and then circulating water through the cracks to generate steam.
But last month, after an article in the New York Times raised questions on whether AltaRock had been forthcoming about earthquakes generated by a similar project in Basel, Switzerland, the Energy Department and the Bureau of Land Management informed the company it would not be allowed to fracture rock until the department completed a new review of whether the project would be safe. The company was allowed to keep drilling, however, down toward the depth at which it would begin the fracturing.
The scientists who told of delays in the project spoke only on the condition that they not be identified, in order to preserve their access to company progress reports. The scientists said that after nearly two months of the highly expensive drilling, the rig had reached depths of less than 4,000 feet. The original schedule called for it to reach a final depth of 12,000 feet, or 2.3 miles, after no more than 50 days of drilling, according to company officials.
The problems are particularly surprising given that the drilling essentially started at 3,200 feet, at the bottom of an older hole at The Geysers.
The company has also raised $30 million in venture capital.
Among AltaRock's high-profile investors are Google and the investment firms Khosla Ventures and Kleiner Perkins Caufield &amp; Byers.
Advocates for the technique, known as an "enhanced geothermal system," say it could eventually generate vast amounts of energy and reduce America's dependence on fossil fuels. But the latest delays come as AltaRock awaits word on whether the federal government will allow the fracturing of rock at all.
The fracturing would be virtually guaranteed to induce earthquakes, which the company has said would be so small as to be nearly imperceptible but which local residents and some scientists fear could be larger.
Although the Basel earthquakes caused only minor structural damage, they frightened many in the city and led to the shutdown of the project there. The Energy Department review, likely to be released in the next few weeks, is expected to compare the Basel and California projects and determine whether AltaRock's effort is safe.
AltaRock declined a request for comment on the status of its drilling.