1.2.1 Power Systems

CLOSED cycle vs OPEN cycle

Open Cycle:

Working fluid is water

Warm surface water brought under vacuum, pressure lowered, water boils at lower temperature

Steam passes through turbine and is condensed into liquid and then discharged. Alternatively, the vapor can be passed through a heat exchanger cooled by cold water resulting in a source of FRESH WATER

Mini-OTEC tested by Lockheed Martin in Hawaii in 1979 produced an gross output of 50kWe. The cold water pipe dimensions were .71m diameter, 670 m long.

OTEC-1 produced 1MWe in Hawaii. The cold water pipe dimensions were 2.55m diameter and 670 m long. (Castellano, 1981)

1.2 Design Reqs

Major Subsystems:

1. POWER PLANT

2. WATER DUCTS

3. ENERGY TRANSFER

4. POSITION CONTROL

5. PLATFORM

1.1 The OTEC Resource

This is the OTEC resource:

Solar energy captured by ocean is a layer 100-300 ft deep
Tropical Oceans are 15 deg N and 15 deg South, have water temps near 82 deg F
Constant day and night, month to month
Temp varies from 80 - 85 deg F
Deeper about 2500 - 3000 ft you have 40 deg F water
Cold water starts below 3000ft
Water accumulated from polar ice melts, flows along bottom across oceans unmixed
Creates 2 layer temperature difference of 40-45 deg F

OTEC uses this resource to produce electric power
Can operate continuously without significant environment impacts if power generated is 0.5 MWe per square mile of ocean surface
This amount would convert 0.07% of the solar energy to electricity

10Million MWe potential from OTEC vs 165,000 MWe Total US Electricity produced in 1987