SKYKOMISH — The search for power in the Cascades is under way.
For the past couple of weeks, the Snohomish County Public Utility District has been drilling in the earth to see where temperatures are high enough to warrant pursuing geothermal energy.
When the drilling is concluded this fall, PUD officials will have a better idea where hot water or steam that can drive turbines might be found deep under the Earth’s surface.
“We’re hoping these wells point us in the best possible direction,” said Craig Collar, senior manager for energy resource development for the PUD.
This is part of an ambitious strategy to develop several different types of alternative energy. The PUD is building a microdam in the Cascade foothills, is buying wind power, offering incentives for solar power and is about to spend $20.1 million trying to generate power from the tides.
The hope is that geothermal electricity could potentially power up to 35,000 homes in Snohomish County by 2020.
“You need to have a blend of different resources,” PUD general manager Steve Klein said.
In the search for geothermal energy, the PUD is drilling on federal forest land near Skykomish. Four other wells are planned, three near Skykomish and a fourth near Sultan. The sites, on federal, state and private land, were selected because they were easy to reach.
Geothermal power is created when steam, heat or hot water from underground reservoirs is used to spin turbine generators. The water is heated by magma farther below. Geothermal plants are operating elsewhere in the nation, including California, Idaho and Nevada.
If the PUD is able to develop geothermal power, it would be the first utility in Washington state to do so, officials said.
It’s not a foregone conclusion that geothermal power here will pan out. Based on the information from these five wells, the PUD will pick a spot to drill a deeper, a 2,000-foot-test hole next summer. If the data from that well is positive, the PUD would search for nearby sites where a plant could be built and actual geothermal wells could be drilled.
Wells for hot water or steam likely would be 5,000 to 7,000 feet deep, Collar said.
The PUD is spending $350,000 to drill the five test holes. Boart Longyear ;http://www.boartlongyear.com/web/guest/homeof Salt Lake City submitted a low bid to do the drilling. Part of the cost could be covered by federal grants, spokesman Neil Neroutsos said. The 2,000-foot hole would cost extra.
In the current drilling operation, a vertical rig about 40 feet tall is attached to a semi-trailer. A hole is drilled about 700 feet straight down. A 6-inch diameter tube is inserted and a 2-inch tube is put inside the first. The area between the tubes is filled with a cement-like material. Water is sent into the smaller tube, following by a thermometer. Over the course of two weeks to a month, the water takes on the temperature of the ground surrounding it, indicating whether a heat source is present.
It’s too early to tell what the holes will yield, officials said.
Drilling of the first hole was discontinued when, less than 200 feet down, water starting pouring out, disrupting the process, Collar said. Crews will try again near that same site, he said.
No such problems were encountered at the current site, crew members said.
Ultimately, a 50-megawatt plant — the size needed to generate power for 35,000 homes — would cost between $150 million and $200 million, Collar said. The PUD likely would borrow money and sell bonds to pay off the loans to build a plant, Klein said.
The earliest a plant would be built is about 2016, officials said. The plant would likely be built in phases of about 10 megawatts at a time depending on its output, Collar said.
“Once the plant is built, the fuel is free,” he said.
Bill Sheets: 425-339-3439; sheets@heraldnet.com.
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