Oregon Volcano to Host Enhanced Geothermal Systems Pilot

[lance rottger]

On a flank of the slumbering Newberry Volcano, a Seattle-based
geothermal development company will be testing technology that could
help bring enhanced geothermal systems mainstream. Enhanced Geothermal
Systems, or EGS, is an emerging form of geothermal energy generation
in which the developer drills a well into hot rock and then pumps
water through that rock to vaporize it, rather than relying on
naturally occurring reservoirs in geothermal hotspots to supply the
steam to make turbines spin. The technology, which has languished for
a couple of decades as the poor redheaded stepchild in the world of
renewable energy development, has "gigantic potential" for helping
meet the United States' electricity demands, says Susan Petty,
founder, president and chief
technology officer of AltaRock Energy. "There are 500,000 MW of
[technically] recoverable geothermal reserves in the western U.S., if
you can make EGS work," Petty says, which is about half the United
States' current electricity demand. Petty isn't the only one talking
up the technology's enormous generating potential. According to
Google.org, a 2007 Massachusetts Institute of Technology report found
that only 2 to 3 percent of the heat 3 to 10 kilometers below the
continental United States could generate 2,500 times the nation's
current total energy use. The report also found that using current EGS
technology, the U.S. couldproduce 1 million to 12 million MW of
electricity--one to 12 times as much power as the country needs
today-- although development costs would need to decline substantially
to make much of that potential pencil out. The U.S. Department of
Energy's Geothermal Technologies Program offers an assessment of the
nation's economically recoverable reserves, suggesting that "more than
100,000 MWe of economically viable capacity maybe be available in the
continental United States," a potential representing about 10 percent
of the nation's overall electricity generating capacity today. "But
you don't want to spend a lot of money on something that doesn't have
a lot of potential," Petty says.
Enter the $43-million Newberry Enhanced Geothermal Systems
Demonstration Project under development by AltaRock and Davenport
Newberry Holdings LLC of Stamford, Conn. The project is sited on the
side of central Oregon's dormant Newberry Volcano, about 20 miles
south of Bend. Through venture-capital funding from backers such as
Google.org, Vulcan Capital, Advanced Technology Ventures, Khosla
Ventures and Kleiner Perkins Caufield &Byers, AltaRock has committed
nearly $23 million to develop and operate the project. The U.S.
Department of Energy has committed an additional $21.5 million in
stimulus funds as a matching grant.
AltaRock and Davenport have finished gathering data and permits, and
will perform reservoir "stimulation" this summer in a geothermal
leasing area about two and a half miles from the volcano's caldera,
outside the Newberry
National Volcanic Monument and its buffer zone. During the test phase,
AltaRock will inject 24 million gallons of cold water, at 800 gallons
a minute over 21 days, into a 10,600-foot-deep test well previously
drilled by Davenport during an earlier but unsuccessful search for a
conventional geothermal resource. What Davenport did find was a lot of
very hot, solid rock--at an average of over 600 degrees Fahrenheit.
Petty told Clearing Up that the Newberry site is a great place to test
AltaRock's technology for several reasons. The heat resource is close
to the surface,
established logging roads provide easy access, and Davenport--which
has already drilled two exploratory
wells--owns local water rights. "Plus, the other neat thing about
Newberry is that it has a generating potential of 250 MW or more in
the area now designated for this project," Petty said. AltaRock aims
to create a 1,500-foot radius of fine fractures in the rock around the
well by using water pressure and the temperature differential between
the cold water and the hot rock, a process called hydroshearing.
Hydroshearing differs from hydraulic fracturing primarily in two ways:
hydroshearing injects cold water at a pressure much lower than that
used in oil and gas fracking, and it does not add chemicals or sand to
the injected water, other than the occasional use of a "weak acid of a
strength comparable to common household vinegar or soda pop . . . used
to dissolve things that might clog up the fractures," according to an
AltaRock white paper. AltaRock will inject the water into the well in
three stages. After each stage, a non-toxic, thermo-degradable plastic
polymer will be injected into the well to
temporarily plug up fracture zones that have already been created, so
that in the subsequent stage, a new
injection of cold water will travel farther down into the well and
create another zone of fractures. As planned, the process continues
until three parallel, horizontal zones of fine fractures have been
created--starting about a mile below the surface, over 3,000 feet in
diameter and nearly 11,000 feet deep. Seismic sensorsAfter that work
is completed, the well will be allowed to heat up, which will break
down the plastic over a couple of weeks and reopen the fracture zones.
Petty, who conceived of the idea to use biodegradable plastic, told
Clearing Up the plastics that will be used are similar to the medical-
grade sort used for dissolving stitches. It's composed of organic
acids and environmentally benign. If all goes according to plan, once
the plastic is gone, what will be left are three independent
geothermalreservoirs that provide, in effect, a large heat exchanger.
Water would be injected into the reservoirs in a subsequent phase of
the Newberry project beginning in summer 2013, and withdrawn through
two production wells that would be drilled. During that phase, Petty
said, the company wants to build a demonstration power project that
would use water heated up by the engineered reservoir to run turbines
generating 10 to 15 MW of electricity, in a closed-loop system that
would continually recycle the water. "Hopefully, we will be able to
scale it up until we get to something that's economically sustainable.
Our goal is to be able to generate more than 100 MW," she said. "But I
want to reiterate that this is experimental, and it will only lead to
a power plant if it is successful and if the regulators agree to let
us have a permit." Petty may be cautiously optimistic because of her
experience with another EGS test project in northern California. In
2008, AltaRock launched a demonstration project about 100 miles north
of San Francisco, at The Geysers geothermal field. The Geysers is home
to "hundreds of megawatts of unused electric power generating capacity
due to the lack of steam caused by several decades of reservoir
depletion," according to Wikipedia. During its test project there,
AltaRock had hoped to redrill a well that had been in place since 1988
and used for years to inject water to produce steam for the existing
geothermal power plants at the site, some of which hadbeen operating
since 1965. In late 2009, AltaRock threw in the towel on the project
after the redrilling effort got stuck three times in unstable caprock.
In the meantime, concerns began to be raised about the induced
seismicity potential of the technology, most of them arising from an
EGS project near Basel, Switzerland, which was suspended in 2007 due
to a damaging earthquake it had triggered. According to AltaRock,
while the Basel project was drilled into a "significant . . . fault
that previously ruptured and heavily damaged the city in the 14th
century . . . there has been geothermal activity production at the
Geysers since 1965. AltaRock's project is located in a seismically
active area adjacent to smaller faults which are not 'locked' due to
the constant stress relief resulting from smaller seismic
movements . . . smaller faults mean smaller events, and the faults in
the Geysers area are significantly smaller than at Basel." Both the
Bureau of Land Management--which has jurisdiction over some of the
project's leases--and the U.S. Department of Energy issued "Findings
of No Significant Impacts" for AltaRock's reservoir creation plan at
The Geysers. But is induced seismicity a potential problem at
Newberry? Ernest Majer, a seismologist with Lawrence Berkeley National
Lab, told Clearing Up that the Newberry site is in a low-seismicity
area, so substantial earthquakes triggered by geothermal exploration
shouldn't be cause
for too much concern. "There hasn't been much seismicactivity recorded
in that area for a long time," he said.According to Oakland, Calif.-
based URS Corp.'s Seismic Hazards Group, the Newberry site is
characterized by a "low to moderate level of historical
seismicity . . . [and] potential EGS induced seismicity poses no
seismic risk to the residents in the neighboring communities." URS
Corp.'s evaluation of seismic risks at the site, which was prepared
for AltaRock, further states that "although there is no additional
seismic risk due to EGS-induced earthquakes, if events of [magnitude]
3.0 and higher were to occur, and we judge the likelihood of their
occurrence to be small, they will probably be felt in La Pine and
Sunriver, but not at damaging levels of ground motions"

http://www.youtube.com/watch?v=Oscqx08zBXQ