Harnessing energy from the sea

By , Staff correspondent of The Christian Science Monitor

It's a strange place for an electrical power plant -- floating at sea some 18 miles and a two-hour boat ride from the big island of Hawaii. But that's exactly why this old Navy oil tanker is here -- to prove that the electricity for 1,000 homes can be generated from these sapphire-blue Pacific waters.

This still-developing form of power from the sea is called ocean thermal energy conversion (OTEC) an awkwardly long and intimidating name for a project now endangered by a budget-conscious Reagan administration.

Technical semantics and politics aside, however, OTEC is based on a simple energy conversion principle that engineers involved with it say eventually could provide tens of thousands of megawatts of renewable electricity from a renewable energy source -- one that light supply electricity for island markets by the end of this decade.

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Although the world's oceans, covering 71 percent of the globe, are only one of the many resources available to mankind, energy experts say they are abundantly rich -- in theory at least. The sea, however, is a particularly hostile frontier. The very forces engineers seek to harness -- waves, salt, and tides -- can snap man-made structures as though they were pick-up sticks or corrode all but the most expensive metals known.

But the search for ways to tap Neptune's power progresses. It is a broad-based hunt, which some expert say should focus on an energy source which, although not renewable, is thought to be plentiful -- offshore oil.

The United States Geological Survey has estimated that between 12.5 billion and 38 billion barrels of undiscovered, recoverable oil lie beneath the US outer continental shelf (OCS) -- a hefty potential compared with the country's proved reserves of 27.1 billion barrels of crude oil.

To date, only minimal drilling has been attempted. Of the 578 million acres of OCS land under federal government control, less than 4 percent of that total has ever been leased to oil companies. Only 2 percent currently is under lease.

Although the drilling so far has yielded mainly "dry" holes, oil company executives contend that if there is a last oil bonanza to be discovered in the United States one of the most likely places to find it is beneath the sea. The best way to get that oil, they argue, is to step up the pace of offshore leasing -- a strategy they hope an apparently sympathetic Reagan administration will support.

But of all the possible energy resources of the sea offshore oil drilling is the most controversial. Environmentalists, who charge that oil companies lack the technological experience to drill safely in deep waters, have fought long and hard to protect ecologically sensitive ocean tracts. They are not expected to surrender now.

Even as this much-publicized fight continues, however, scientists and engineers are charting calmer waters as they seek out the ocean's energy potential.

Among the more promising resources they are studying is wave power. The United States, Great Britain, and Norway are all experimenting with wave projects. The Japanese already have built an experimental barge carrying a wave-fed turbine that generates electricity for transmission to shore.

There are also energy resources in the tides, which have an estimated potential for replacing 1 billion barrels of oil on a worldwide basis. The French already have proved this power can be tapped; since 1967, they have operated a 240-megawatt tidal-powered plant on the La Rance estuary.

Engineers also are studying the possibility of capturing the energy created where freshwater rivers meet the ocean, a process known as salinity gradient. In theory, they say, if all this power could be converted, it would supply 10 percent of the world's present energy demands.

It is OTEC, however, which today seems the form of renewable ocean energy most likely to hit the commercial market first.

Unlike other ocean energy systems, which generally still require years of research and technological development to define their commercial feasibility, OTEC engineers say this concept appears to have the crucial ingredient necessary for marketing any alternative energy technology: a projected production cost equal to, or lower than, the cost of producing a barrel of oil.

So far, OTEC has been demonstrated only on an experimental basis. Tests conducted in 1979 on a barge off the coast of Hawaii showed that the system could work. Mini-OTEC, as the $2.5 million project was called, produced 50 kilowatts of electricity, enough to power the barge's operations and still have a surplus of 12 kilowatts, or roughly enough energy to light 120 100-watt bulbs.

In the past, OTEC skeptics have claimed that engineering difficulties would prove insurmountable. As recently as 1978, the Congressional Office of Technology Assessment (OTA) reported that OTEC "probably could not become a viable part of the US energy system in this century."

Such challenges, however, say OTEC engineers, are being overcome one by one. And although a 1980 OTA report on OTEC claims that "formidable engineering development challenges" remain in creating a large commercial system, it also takes note of "the substantial and significant work" accomplished in the past two years, with the operation of Mini-OTEC being one of the most important technical achievements.

"If there's a weakness [with OTEC], it's something we don't know yet. I can't imagine what it would be," says one TRW scientist who was involved with that company's OTEC program for seven years. "OTEC is not only way ahead of all the others by a couple of orders of magnitude, it's way ahead of [land-based] solar."

First proposed a century ago by French scientist Jacques d'Arsonval, OTEC is a relatively simple energy conversion concept. But it did not attract much serious scientific attention until the oil crisis of 1973, when the search for alternative energy sources began in earnest.

OTEC is essentially a low temperature boiler and gas turbine system. It relies on the temperature difference between the 79-degree F. sun-heated surface waters of the tropics and subtropics and the 40-degree waters a half-mile below the warm surface.

Electricity is generated by using warm sea water to vaporize a liquid like ammonia, which then turns the turbo-generators. The ammonia gas is passed through another tank where it is condensed by cold waters pumped from depths of 2,000 feet or more. From there, the cycle starts over, with the same ammonia and with more warm water from the virtually limitless sea.

On board OTEC-1 -- a $54 million, US Department of Energy-funded project -- engineers are not producing electricity because the one megawatt system has no turbine. Their work instead has focused on environmental studies and the engineering problems still involved with OTEC -- snags which engineers say result not from technological unknowns but from difficulties of building equipment large enough for a commercial operation. Such experiments are necessary before the next phase of OTEC can be started, the construction of a 10 -to-40 megawatt pilot plant.

Experts estimate that a 40-megawatt plant today would cost approximately $300 million -- no small amount of money, particularly when compared with the much lower capital expenses involved in building a coal power plant.

But because there are no fuel costs for an OTEC system -- sea water, after all, is free -- the payback time for an OTEC plant may be as early as one year, say engineers. At that rate, according to Lockheed Ocean Systems, OTEC could be competitive with oil by the late 1980s and with nuclear and coal by the late 1990s.

OTEC, however, is not likely to be the answer to your energy problems if you live off the coast of Alaska or even California. The only place where both the warm and cold waters needed to power an OTEC system can be found are in the tropics and subtropics -- a band approximately 25 degrees north and south of the equator.

Still, it is in these waters, which include the US Gulf Coast, that some of the world's most energy-starved lands can be found. They include many islands whose residents currently are forced to rely almost entirely on imported oil to meet their energy needs.

Yet in spite of its apparent potential, OTEC appears to be headed for rougher waters, at least in the US. After spending an estimated $100 million on OTEC research over the past five years, the federal government is planning to abandon ship.

The $38 million proposed for OTEC under the Carter budget -- money which would have gone in part to the development of a pilot plant -- has been eliminated from Reagan's proposed 1982 budget. His budget advisers contend that OTEC has been so successful that it should now be taken over by private enterprise.

Engineers argue, however, that without federal help for the dive from proved small-scale systems to the unknowns of a commercial-size plant, the industry's momentum will be seriously -- and perhaps irrevocably --dissipated.

The administration's decision to leave the pilot plant high and dry, they say , also leaves a wide-open market for the Japanese, who are steaming ahead with OTEC development. Already, the Japanese have been contracted to provide a 10 -megawatt pilot plant, set for operation this August, for the South Pacific island of Nauru.

The cutback "will cause a significant delay in the development of OTEC and the loss of much of the industrial capability that's been developed over the past seven years," says Fred Naef, president of the Ocean Energy Council, a non-profit, educational organization.

"I don't think it necessarily means the death of OTEC [for the US]," he continues. "The survivors will have to regroup and find another way to get along. . . . I think OTEC will survive, but it will happen much later and it will be much more expensive in the long run."

Although there is a possibility that Congress may restore some of OTEC's lost dollars. This is considered remote at best by insiders.

"OTEC does not have a constituency, that's a big problem," explains Roger Fuller, program manager for ocean energy at Lockheed. "People don't understand how you can get electricity from the ocean. It sounds crazy to them."

Of some comfort to despairing OTEC advocates is the fact that last year, two OTEC bills were passed by Congress: one which, among other things, sets a goal of the installation of 10,000 megawatts of OTEC power by 1999; and a second piece of "wrap-around" legislation that clears the bureaucratic way for OTEC in virtually every area from licensing to loan guarantees.

The risks, however, are still considered too great by some of the larger aerospace corporations that have been at the forefront of OTEC development. These companies are expected to put OTEC projects on a side-burner, leaving the field to entrepreneurs willing to hunt down the venture capital needed for an OTEC system.

"We're at the point now," says one OTEC engineer from a major corporation, "where an entrepreneur or a guy with a lot of guts has to come into the arena. . . . The technology is definitely there. But it will take entrepreneurial initiative to go the next step."

Tomorrow: Pursuing the elusive "Law-of-the-Sea"

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