Environmental Engineering Reference
In-Depth Information
Fahrenheit (32º Celsius) at the surface. Far below the surface,
though, the temperature of the ocean can be much cooler—
perhaps as cold as 55ºF (13ºC). Heat is another form of energy,
just like the motion in moving waters. Scientists have found
several interesting ways to turn the ocean's heat into electricity.
These different methods are called ocean thermal energy
conversion (OTEC).
One method uses the heat in the water to make the substance
ammonia boil. Ammonia boils at a much lower temperature
than water. The warm water travels through a pipe into a
container that holds ammonia. When the ammonia boils, it
becomes a gas that is forced past a turbine, which spins, causing
a generator to produce electricity. (The electricity is carried by
cables to land.) Then, cold ocean water in another pipe is used to
turn the gas back into a liquid, and the ammonia can be reused.
Another OTEC system turns the warm surface water into
steam to power a turbine. In a process that is called lash
evaporation, the warm water goes from a pipe into a container
in which a short, rapid burst of heat creates the steam. After the
steam leaves the turbine, it passes through tubes placed in the
colder water. Once again, the colder water turns the steam back
into water.
The irst working OTEC power system was built in Cuba in
1930. It produced 22 kilowatts of electricity, but it required
more power than this to work. A power plant must generate
more power than it uses, or it does not make sense to build it.
The owners would lose money. Newer OTEC systems are able to
produce more electricity than they use. Plans are underway to
test small OTEC plants that could produce up to 10 megawatts
of power.
