Tapping energy needs from volcanic Cascades

The geothermal energy resources locked beneath the Cascade Mountains of Washington, Oregon, and northern California may be worth digging into, and the Eugene Water and Electric Board is doing just that.

The water and electric power utility arm of this wester Oregon city of 100, 000, a pioneer in the search for alternatives to hydro and thermal sources of electric energy, has entered into an agreement with Southwest Drilling and Exploration Inc. of Central, Utah, to drill as many as seven temperature- gradient wells from 500 to 2,000 feet deep in the central Oregon Cascades.

The key was the award of a $300,000 federal grant to the Eugene utility for the test-drill project. The initial phase will cost about $450,000. The federal grant money will be augmented by $50,000 each from Eugene; Southland Royal Company, a geothermal exploration firm; and Sunoco Energy Development Corporation, a petroleum company.

The Cascade Mountains were the scene of the most recent major volcanic activity on the US mainland. Mt. Lassen, at the southern end of the range in northen California, erupted as recently as 1924. Mt. Hood, which looms picturesquely over the city of Portland, Ore., was an active volcano in the latter part of the 1800s, and peaks along the range from the Canadian border into California, such as Baker, Skagit, Rainier, St. Helens, Adams, Jefferson, Three-Fingered Jack, the Three Sisters, Thielsem, and Shasta, all erupted in very recent geologic times.

Circular 790 of the US Geological Survey, entitled "Assessment of geothermal Resources of the United States, 1978," estimates that the "identified accessible resource base" for the Cascades is a heat equivalent of more than 9 billion barrels of oil. In addition, the circular estimates the "undiscovered accessible resource base in the Cascade Mountains to be 20 times that identified and possibly even greater."

In other words, slumbering under the rugged Cascade peaks may be a heat energy resource the equivalent of 200 billion barrels of oil.

Tapping geothermal energy has taken two basic forms, and the practicality of both has been amply demonstrated. The economic practically is becoming more apparent daily as the United States and the world face a deepening energy shortage.

The use of hot water from underground sources for heating has gone far beyond the experimental stage.

Reykjavik, Iceland, once had air pollution from the burning of coal that rivaled that of Pittsburgh in the 1930s. Reykjavik now uses hot water from geothermal wells for heating and other purposes and is pollution-free. Water is brought to the city through a 12-mile pipeline and is potable for drinking and otherwise usable after the heat is removed.

The buildings of the Oregon Institute of Technology in Klamath Falls are heated by a geothermal system at a cost of less than 10 percent that of conventional methods.

Northwest Natural Gas Company, through a subsidiary, Northwest Geothermal Corporation, together with Oregon's Department of Geology and Mineral Industries , and helped by a grant from the US Department of Energy, has drilled a 4,042 -foot wall at Old Milk Flat on Mt. Hood. The temperature obtained at the bottom is 180 degrees F. The well may be deepened 1,000 feet, although the 180-degree heat is enough for a viable project. The company hopes to send the water to the Portland area through a 40-mile, 42-inch pipeline to provide heat for the city.

Electricity from geothermal resources is a tougher proposition than discovering, transmitting, and using hot water for heating. But that process also has gone beyond the experimental stage. It is the electric energy potential that most interests the Eugene Water and Electric Board.

Pacific Gas & Electric Company now is generating more than 600,000 kilowatts from geothermal steam at the Geysers field in northern California. That is more than the entire hydroelectric output of the Bonneville Dam on the Columbia River. By 1982, the company expects to be producing 1.2 million kilowatts at Geysers.

Steam, necessary for generating electricity, is usually found at much greater depths than mere hot water. Steam, once it is found, cannot be transported great distances as easily as hot water, so that steam generating plants using geothermal sources have to be near the source. That consideration and the necessity for overhead transmission lines for the electricity bring environmental impact into play.

The environmental drawbacks, however, are much easier to overcome than those associated with increased production of electricity from either nuclear plants or coal-fired plants.

The drilling by the consortium of which the Eugene utility is a member is on land that has recently been logged off by the clear-cut method and can be reached by already existing roads.

Keith Parks, general manager of the utility, says last summer's drilling in the Santiam Pass and Breitenbush areas of the Central Cascades was carried out both on private and national forest land.

The Cascade Range covers a vast reservoir of geothermal heat. If only 10 percent of the potential indicated by the Geological Survey report could be tapped, it would be the energy equivalent of the oil reserves in the Alaska North Slope field. Or, as C. Girard Davidson, general counsel for the Bonneville Power Administration and former assistant secretary of the interior, said recently in an analysis of the Geological Survey circular: "A 10 percent realization of the Cascades' geothermal potential would provide the equivalent of the US imports [of oil at the 1978 rate] from Iran for 165 years."

Mr. Davidson believes that, if the results of last summer's drilling program of temperature-gradient wells live up to expectations, the deep drilling that will take place this summer will be crucial in determination of the available quantity and quality of the geothermal water and steam. It is hoped, he says, that sufficient quality and quantity will be discovered so that the hot water transmission and steam generation projects envisioned will be economically feasible and can proceed in 1981.

Eugene officials say the drilling went roughly on schedule last year, although some conditions were tougher than anticipated. The final operational phase was completed on the last possible day at one site, as equipment was disassembled and the crew scurried out only a few minutes before the first heavy snow of the winter struck.

The temperature data and core samples from the drilling were, at this writing , being analyzed in two laboratory projects. One is under the supervision of Dr. Melvin H. Beeson of the Branch of Geochemistry and Petrology of the US Geological Survey at Menlo Park, Calif. The other is headed by Dr. David Blackwell of the Geothermal Laboratory of Southern Methodist University at Dallas.

Officials of the Eugene utility expect the data to be assembled and analyzed, and conclusions to be drawn from them, by July 1. Until then, no definitive assessment of last year's work can be made. The utility, however, was optimistic when the project was undertaken, and that optimism continues, since apparently nothing occurred during the drilling operations that contradicted preliminary estimates of the area's geothermal potential.