GEOTHERMAL RESOURCES

Geothermal resources include the exploitable heat stored in the Earth's crust that can be utilized either by conversion of heat energy to electrical or mechanical energy or by direct utilization of the heat. Only a small fraction of the potentially exploitable geothermal energy is utilized commercially.

The Geothermal Steam Act of 1970 provided that the Secretary of the Interior lease Federal lands to private industry for exploration, development, and utilization of geothermal resources. Under regulations published in 1973, the Geological Survey supports the geothermal resources programs in several ways: evaluation and classification of the resources of Federal lands, assurance of compliance with applicable regulations before issuance of permits for exploration and development of resources on Federal lands, and supervision of the conduct of operations on leased Federal lands.

Beginning in fiscal year 1971, the Geological Survey started classifying Federal lands with geothermal resources adequate for commercial utilization or lands identified as having competitive interest of private companies as Known Geothermal Resource Areas (KGRA's). Lands within KGRA's are leased by competitive bidding. Other lands are leased noncompetitively to the first qualified applicant.

At the present time, the Geological Survey has established 108 KGRA's; these comprise 3.38 million acres and are within 11 Western States. At the end of 1979, 268 tracts comprising 541,000 acres had been leased within the KGRA's, an increase of nearly 30 percent over the preceding year. A total of 1,029 tracts comprising 1.75 million acres leased noncompetitively were active in fiscal year 1979, an increase in acres of 13 percent. The number of geothermal wells drilled on Federal, State, and private lands increased about 60 percent over the preceding year. Fewer wells (11 instead of 13) were drilled on Federal leases, but approvals to drill 336 wells have been issued.

The United States is the world's leading producer of electricity from geothermal resources. Nearly all U.S. production occurs at The Geysers in California, where 13 powerplants located on State and private lands, generate 663 megawatts of electricity, which is sufficient to meet the total demands of a city the size of San Francisco. The company plans for future developments include increasing power production to 2,000 megawatts within 20 to 25 years. Construction of a 110-megawatt plant on Federal land will commence in early 1980, and commercial production is scheduled for 1982.

The geothermal resource at The Geysers is the only one in the United States known to contain enough dry steam for commercial electrical power generation. At all other KGRA's with known commercial potential for elec

tric power generation, the geothermal resources provide heated water rather than steam.

The power generation techniques needed to utilize hot water differ from those employed at The Geysers. Usually the geothermal water, which comprises approximately one-fourth of the fluid, is flashed to steam. The flashed steam drives turbogenerators, and the remaining liquid is injected back into the geothermal reservoir. Plants that will use flashed steam are in advanced stages of construction at East Mesa, Calif., a 48-megawatt plant; at Heber, Calif., a 45-megawatt plant; at Baca Ranch, N.M., a 55-megawatt plant; and at Roosevelt Hot Springs, Utah, a 20-megawatt plant.

Another technique for generating electrical power using heat from geothermal water is the "binary process." In this process, heat from the water is transferred by a heat exchanger to a second fluid having a low boiling temperature to produce vapor to drive a turbogenerator. A 10-megawatt plant using this technique has been completed on a Federal geothermal lease at East Mesa, Calif., and is nearing start-up (fig. 1). Other powerplants that will use the binary process are in various early planning stages.

With present technology, electrical power generation is limited to geothermal water sources with temperatures above 150°C. Lower temperature waters offer a potential for numerous applications for direct use of heat energy in food and industrial processes, agriculture (fig. 2), space heating of buildings, and other uses.

Prior to 1979, direct use of geothermal water heat was limited to heating of buildings in Klamath Falls and a few other locations in Oregon, Idaho, and Nevada. In addition, hot water was utilized at an onion drying plant at Brady Hot Springs, Nev., a milk pasteurization facility in Oregon, and greenhouses in Lordsberg, N. Mex., and Marysville, Calif. At the end of fiscal year 1979, 21 projects are in advanced stages of planning and development in Texas and in eight Western States under Department of Energy sponsorship. Sixteen of these projects involve space and water heating of hospitals, schools, and other public buildings, and five will provide heat for food processing. Other applications include a rose greenhouse in Utah, a prawn farm in Coachella Valley, Calif., a sugar beet refinery at Brawley, Calif., and a cattle warming facility in South Dakota.

A variety of proposed applications for "cascading," whereby geothermal energy can be utilized more effectively by using the cooler spent water from one process for one or more separate subsequent processes, are in the early stages of planning and evaluation. For example, the use of waste water from electrical power generation can be used for industrial processes, and the waste from the industrial processes can be used for space heating of buildings.

Office

MISSION

During the 1970's, the general public became acutely aware of the energy crisis as reflected in long gasoline lines and escalating gasoline and fuel oil prices. The growing shortage of nonreplenishable energy resources such as petroleum poses but one of the critical environmental problems being addressed by the U.S. Geological Survey. Traditionally, the Survey has responded to environmental information needs on a case-by-case basis, utilizing one of its core disciplines-geology, hydrology, or cartography. However, during the last decade, it has become obvious that environmental studies must be a cooperative effort between the scientists in these diverse fields and specialists in other disciplines such as urban planning, economics, geography, and remote sensing. In addition, the information gap between these scientists and the potential users of these data-land-resource planners and decisionmakers-has widened because of advancing technology and increased specialization.

These two specific problems, the need for an integration of scientific disciplines and the requirement for information transfer from the earth scientist to the policy and decision makers, led to the creation of the Land Information and Analysis Office in 1975. The goals and efforts of the Land Information and Analysis Office illustrate the diversity of scientific work currently being done on these environmental problems.

The objectives of this Office are:

• Development and application of multidisciplinary earth sciences, other natural sciences, and geographic technology in support of land-resources decisionmaking and planning.

• Mapping current land use and land cover. Meeting Geological Survey obligations as required by the National Environmental Policy Act (NEPA).

• Collecting, processing, and distributing remotely sensed data and applying other aspects of space

technology in support of land-resources planning

and management and environmental impact
analysis.

The task of achieving these objectives is carried on by the following multidisciplinary programs:

• Earth Sciences Applications (ESA).

• Resource and Land Investigations (RALI).

(The combination of ESA and RALI is also known as the Land Resources Data Applications Program for budget purposes.)

• Geography.

• Earth Resources Observation Systems (EROS). • Environmental Impact Analysis (EIA).

SELECTED

ACCOMPLISHMENTS

During 1979, the Land Information and Analysis Office initiated and concluded a variety of multidisciplinary projects. A representative selection demonstrating the diversity of this effort is shown by the following short reports presented in this volume:

Tracking the Ixtoc 1 Oilspill Across the Gulf of Mexico. Earthquake Prediction for a Seismic Gap in Alaska. Interpretive Reports To Aid Regional Planners.

A Computer Model That Helps Protect the Environment.

Protecting the Environment in Alaska.

Land Use Maps and Data Application-Three Mile
Island Powerplant Site.

Land Use and Land Cover Maps and Data for Our Nation.

Helping Planners and Decisionmakers Use Earth
Science Information.

New Advances in Satellite Image Data Handling and
Application.

BUDGET AND PERSONNEL

Obligations for Land Information and Analysis Office activities in fiscal year 1979 amounted to $23.96 million, an increase of 3 percent over fiscal year 1978 (see table). The work of the Land Information and Analysis Office is partly accomplished through contracts to private industry and research grants. During fiscal year 1979, $8.51 million (36 percent) was expended on contracts. Contract services were the major source of operational support at EDC. Cooperative programs with State agencies were carried on by the Geography Program for land use and land cover mapping. The programs of the Land Information and Analysis Office employed 228 full-time career employees in 1979, of which 164 positions were assigned to the Office's programs and 64 were assigned to other Survey Divisions to support work of the Land Information and Analysis Office. There were also 74 temporary or part-time employees. In addition, contract support services at EDC amounted to 306 person years. Personnel of the Topographic Division assigned to EDC are included in the above numbers.

Land Resource Data Applica

Other Federal agencies $1.64

SOURCE OF FUNDS

TOTAL $23.96 MILLION

USE OF FUNDS

On June 3, 1979, the Ixtoc 1 oil well, 50 miles off the coast of Mexico, blew out and caught fire. Totally out of control, the well poured as much as 100,000 barrels of oil per day into the Bay of Campeche. The oil flooded out into the Gulf of Mexico, threatening beaches in Mexico and the United States. It become imperative to determine the extent of the oilspill, to follow its movement across the Gulf of Mexico, and to obtain this information as quickly and economically as possible.

The Geological Survey investigated the use of multispectral scanner data from the Landsat 2 and 3 satellites to monitor the movement of the oil. Each Landsat image can inexpensively portray 13,225 square miles of the Earth's surface. Each satellite is able to scan a strip of images of the Gulf on one day and the adjacent strip on the west the next day. The entire Gulf of Mexico can be imaged in about a week.

Each of the two Landsat satellites now in orbit returns to nearly the same spot above the surface of the Earth every 18 days. Because their orbits are similar but 9 days apart, the two satellites can monitor a given feature, such as an oil slick, every 9 days for as long as both operate.

The illustrations show how Landsat data can be used to track the movement of a large marine oil slick.

Flames from the burning gas and oil leaking from the damaged Ixtoc 1 well are shown in figure 1. The gray fluid surrounding the flames is oil. A boom constructed later did not keep the oil from moving farther out into the Gulf of Mexico.

Oil and smoke streaming westward from Ixtoc 1 are shown in figure 2 in a digitally enhanced Landsat image. A thin coat of oil on the water appears black. The gray area represents thicker oil, and the whitish stringers are thick ropy heavy oil. Smoke from the burning gas and oil and clouds formed by superheating of the atmosphere appear white. The puffy white spots in the image are natural clouds.

Oil approaching the Mexican coast is shown in a photo-optically enhanced Landsat image in figure 3. The land is different shades of gray, and the clouds are white. The sea is light gray, and the oil is dark gray. Some of the oil eventually reached the Texas beaches such as the one near Corpus Christi (fig. 4).

Important factors in the use of Landsat images to detect and monitor marine oil slicks are enhancement techniques, sun angle, and sea state. Special image enhancement is needed because differences in the reflectance of oil and water are subtle. Two common types of enchancement are photo-optical and digital. In photo-optical enhancement, the negative of the image is processed to increase film contrast in the same manner as for an ordinary photograph. To increase the contrast even more, the process is repeated.

When digital enhancement techniques are used, the brightness values of the innumerable tiny picture elements that make up a Landsat image are recorded on a computer-compatible tape and multiplied by a digital computer to increase the contrast of the image. The multiplication may be repeated several times to further increase the contrast. Enhancement can be observed and controlled through the use of specialized image analysis equipment.

Sun angle and sea state are also important in determining whether an oil slick can be detected by Landsat. Slicks are more easily spotted when winds are low to moderate and the sun is less than 50 degrees above the horizon because sun glitter is greatest under these conditions. The glitter results from the reflection of sunlight from extremely small waves. Because oil has a calming effect on the waves and removes the glitter, an oil slick commonly appears dark on Landsat images.

The use of Landsat to detect and track marine slicks has important environmental and exploration applications. Landsat data can assist in the following:

• Locating oil slicks that originated from manmade sources such as leaking wells, broken pipelines, and discharges from ships.

Finding the origin of spills.

Exploring for oil by detecting natural marine seeps from undersea sources of petroleum. Development of oil resources on the Outer Continental Shelf of the United States is being monitored by the Geological Survey using geological, geophysical, engineering, and remote-sensing techniques. The use of satellites to monitor oil on the surface of the sea is an example of a new technique that may assist in safeguarding valuable offshore environments and at the same time help in developing a needed resource.