Engines of Our Ingenuity

No. 425:
COLD WATER

by John H. Lienhard

Click here for audio of Episode 425.

Today, let's throw cold water on the inventive mind. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Deep in the ocean, 2000 feet below Keahole Point in Hawaii, the water is cold. Engineers at the Natural Energy Lab have run a pipe down to reach it. They bring 25,000 gallons a minute to the surface, and they do wonderful things with it.

It may sound strange, but the first thing an engineer thinks of when he sees all that cold water is power production. Any heat engine needs a flow of heat from a hot place to a cold one. Heat flowing from the 80-degree Pacific sea water into 43-degree water from below can be made to generate electricity. That's the first thing these engineers set out to do.

They've built the power plant, but it's been hard. Normal plants operate between a furnace at thousands of degrees and a cold condenser. They're trying to milk energy from less than a 40-degree difference. They can produce power, but so far it costs more than energy from cheap oil. It's a start, and it can be improved. When oil prices rise, it could be attractive.

Yet, as these engineers worked, that modest temperature difference tickled their inventive genius. They saw how it could make food. For example: now they run cold water pipes through beds of strawberries and lettuce. The pipes cool them so they can grow in the warm Hawaii climate. But water from the air also condenses on the pipes. Then it drips into the beds and irrigates them.

The engineers also mix the cold water with warm surface water and use it in lobster farms. The water is the same temperature -- year around. These lobsters don't have to hibernate through winter. They take only half as long to mature.

Possibilities keep tumbling out of that pipe. The purity of water, so far from surface pollution, makes it ideal for growing algae to make pharmaceuticals. And now the lab has taken up fish farming as well. That water can produce a whole megawatt of power. They even use it in their air conditioning.

The creative mind is fed by oddity -- by the thing out of the ordinary. These Hawaiian engineers, faced with the oddity of cold water pouring into a warm place, have feasted upon the image. They've seen possibility within it. That recognition has given us lobsters, strawberries, and electricity where no one would have looked for lobsters, strawberries, or electricity. These engineers have plumbed the wealth of their imaginations and found new wealth in the sea.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Halloran, R., Tapping Ocean's Cold for Crops and Energy. The New York Times, 'The Environment,' Tuesday, May 22, 1990, p. B6.

I'm grateful to

Ms. Rebecca Crockett, Public Affairs Specialist, and
Dr. Thomas H. Daniel, Technical Director
Natural Energy Laboratory of Hawaii
P.O. Box 1749
Kailua-Kona, Hawaii 96745
808-329-7341
for additional technical information.


The Engines of Our Ingenuity is Copyright © 1988-1997 by John H. Lienhard.

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