Tapping volcano's pent-up steam to light Hawaii

An active volcano is helping to light this island.

More than a mile below the earth's surface, molten magma under the volcano Kilauea heats porous rock. That rock turns rainwater that has seeped through the ground into steam, creating one of the hottest geothermal reservoirs in the world. Hawaii then taps that reservoir to generate electricity and help lift itself out from under the thumb of imported oil.

Although many states are pursuing alternative energy programs, Hawaii's struggle is particularly crucial: No other state in the country is as dependent on imported oil as Hawaii.

Approximately 92 percent of the state's energy needs are met by imported oil - at a cost of $1.5 billion in 1981. As oppressive as such a dark cloud of energy dependence has been, however, it still has had something of a silver lining: Hawaii has been propelled to the forefront of the search for safe, renewable energies.

''I'm assuming oil prices will rise,'' says Hideto Kono, the state's energy resources coordinator. ''We can never count on the Middle East being stable.''

The Puna geothermal plant on the ''big island'' (Hawaii) generates 3 megawatts of electricity. It is one of Hawaii's most commercially successful energy projects to date - only the second geothermal plant in the country. Built through state and federal funds at a cost of $13 million, the plant's operations were turned over March 1 to the local utility, Hawaii Electric Light Company, which will service some 800 local families with electricity generated by geothermal steam.

According to a 1981 study by the Lawrence Berkeley Laboratory and the state's Department of Planning and Economic Development, 100 megawatts of baseline capacity could be built at Puna by 1990 and about 1,000 megawatts by 2005. Already, geothermal energy has proved to be so commercially attractive that two companies have each drilled two exploratory wells in the Puna area. The local utility has asked for proposals for an additional 25 megawatts of geothermal capacity to be built on the big island.

There are some problems, however. Because Kilauea is an active volcano and has erupted in recent years, geothermal plants built here must be portable. The 3 megawatt facility is, according to Dr. Bill Chen, project manager. There also has been some local opposition because of the noise and smell caused during the facility's construction.

Perhaps more important, though, is the need for an underwater cable. The cable would carry electricity from the big island -- which needs only a fraction of the energy that the geothermal wells can produce -- to heavily populated Oahu , which accounts for 80 percent of Hawaii's energy consumption.

Although the state and Hawaii Electric Light are both working on the cable problem, it is a formidable task. No undersea power cable anywhere has operated at depths greater than 1,800 feet or over distances of more than 80 miles. A cable between Oahu and the big island would have to stretch 150 miles at a depth of 6,900 feet.

Hawaii is continuing its search for renewable energy on many fronts - although nuclear power, which enjoys little popular or political support here, is not one of them.

Among the favorably regarded alternative energies is wind, which, like geothermal, is sufficiently well developed as a technology to attract private-sector dollars. Hawaii is one of the best places in the world for wind turbines, with five to 20 mile per hour tradewinds blowing 70 percent of the time. On the windward side of Oahu, the world's largest wind turbine farm is under construction. It could provide 80 megawatts of power by 1985 - enough to save up to 600,000 barrels of fuel oil yearly.

One alternative energy source already in widespread use is bagasse -- sugarcane waste which is burned to make electricity. Bagasse currently supplies 7 percent of the state's energy needs.

Other forms of renewable energy in use or being considered are hydroelectric (which provides 1 percent of Hawaii's energy needs) and solar energy, and ocean thermal energy conversion (OTEC). OTEC taps the energy potential of the temperature difference between the ocean's sun-warmed surface water and its chilly depths.