The existence of significant geothermal resources in Alaska is suggested by approximately 100 thermal springs and more than 80 volcanoes, most of which have been active within the past million years. The potential for development of geothermal energy appears to be greatest along the Aleutian volcanic arc and in the large andesitic volcanic pile in the western Wrangell Mountains of east-central Alaska. Many of the volcanic centers in these two regions are similar to geothermal areas elsewhere in the world now being either actively prospected or developed. The Aleutian arc, for example, is near the contact between the North American and Pacific plates and contains more than 40 historically active volcanoes, at least 20 calderas, and 34 reported thermal springs, including so e with subsurface temperatures estimated by chemical geothermometers as being above 200°C. The Wrangell volcanic pile contains many large stratovolcanoes, one of which, Mount Wrangell, still displays fumarolic activity near its summit. Others, such as nearby Mount Drum and Mount Sanford, are young volcanic centers whose size and silicic composition make them attractive as geothermal exploration targets.

Thermal springs in interior and southeastern Alaska are along fractured margins of granitic plutons and appear to represent deeply circulating meteoric water. Chemical geothermometers and the geologic setting suggest subsurface temperatures less than 180°C and reservoirs characterized by relatively low-recharge rates. Because of the demand for energy in remote regions, these relatively small geothermal areas may be among the first to be utilized in Alaska. Much of the potential use of geothermal energy in Alaska is for space and process heating rather than for producing electricity, but requirements and costs of electricity are changing rapidly.

The Wrangell volcanic pile is adjacent to major transportation routes and an intra-Alaska use would be likely for energy produced from a geothermal source in this region. The economic value of the potentially large geothermal areas in the Aleutian Islands and Alaska Peninsula, however, probably lies more in supplying the needs of industries with high-energy requirements.

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