A new kind of PORSHE joins the race for energy

Japanese scientists are proposing to float giant rafts in the South Pacific to convert sun and sea into a powerful new form of inexhaustible energy.

The idea is to extract from sea water hydrogen, which, when liquefied, could be carried in tankers to feed the world's industries and its cars long after global crude oil supplies have run out.

The Project for Ocean Rafts System for Hydrogen Economy - known as PORSHE for short - is the brainchild of Tokio Ota, a professor of engineering at Yokohama National University near here.

He has been working on the idea for the past seven years, and now believes it is close to becoming reality, if Japanese government and industrial financial backing is available.

The most likely site is off the group of South Pacific islands now known as the Republic of Belau (formerly the American-administered territory of Palau).

In essence, says Professor Ota, it's simply a matter of separating water into its component parts of hydrogen and oxygen.

''Hydrogen in liquid form has a calorific value 2.5 times that of gasoline.''

''Unlike other alternative energy sources now being touted - like solar and wind power - liquid hydrogen can be stored and transported just like gasoline. So it is an eminently suitable replacement for petroleum fuels in cars and even aircraft.''

(Other experts point out that liquified hydrogen has to be kept at very low temperatures or absorbed on special materials. It is also highly explosive if it leaks. All this presents serious problems in everyday use.)

Even more important: it doesn't pollute.

The main problem that has held up development of hydrogen as an energy source , however, is the immense amount of energy needed for the separation process.

This is where PORSHE comes in.

Ota envisages floating a fleet of huge rafts to utilize the strong sunlight of the South Pacific.

Using plastic parabolic mirrors resistant to salt damage, the rafts would concentrate the sun's heat to power steam turbines.

These, in turn, would generate the necessary electricity to first desalinate the sea water and then break it down into oxygen and hydrogen through electrolysis.

The final process would be supercooling to produce liquid hydrogen and liquid oxygen.

The PORSHE Project Study Team, involving 12 Japanese companies, was formed in September 1978.

But it was still really only an idea until Belau Vice-President Alfonso Oiterong heard of it and wrote Ota offering the island republic as a site for the first raft.

The Porshe team initially wants to build a 100-meter-square raft on site at an estimated cost of $25 million.

They estimate it would be able to produce 2,000 cubic meters of hydrogen a day, pumped via an undersea pipeline to power a small coastal factory.

Ota says it would also be possible to produce ammonia by combining the hydrogen with nitrogen extracted from the air. Margarine and soap could be manufactured through chemical reactions with hydrogen and coconut or fish oil, he says.

At this stage no target date has been set for floating the first raft, as there are still many aspects of the project to be studied. Of particular concern is the low level of technology in Belau which, Ota believes, could hamper effective use of the sophisticated technologies involved.

''At this stage, we would need some sort of firm local economic base before moving on to something more grandiose - especially serving as a supply source for world industry,'' he explains.