Ocean thermal energy conversion
(OTEC) systems
報告學生：周暐祥
報告日期：98/12/11
Introduction
• Renewable Ocean Energy:
Tides, Currents, and Waves.
• Oceans cover more than 70% of Earth's
surface, making them the world's largest solar
collectors.
What is OTEC
• OTEC systems use the ocean's natural thermal
gradient—the fact that the ocean's layers of water
have different temperatures—to drive a powerproducing cycle.
• In deep tropical waters ocean surface temperature can
be as high as 27 ℃; and at depths as close as 1000 ft
below the surface, temperature can be as low as 4 ℃.
OTEC system
• There are three types of electricity conversion
systems: closed-cycle, open-cycle, and hybrid.
• Closed-cycle systems use the ocean's warm surface
water to vaporize a working fluid, which has a lowboiling point, such as ammonia.
Closed-loop OTEC facility
Closed-loop OTEC cycle
An OTEC system application case
• Hydrogen can be produced via electrolysis using
electricity generated by the OTEC process.
• Stored hydrogen can then be transported and used to
power fuel cells.
Results
• Results for the given problem data are given in Table
1. At g = 79%, 13,580 kW of power are generated by
the OTEC system requiring close to 61,000 kg/s of
cold ocean water utility. This is with respect to almost
50,000 kg/s of surface ocean water utility .
Table 1
Conclusions
• Beneficial factors that should be taken into account include
OTEC's status as a renewable resource (with no combustion or
waste products or limited fuel supply), and the possibility of
combining it with solar energy, aquaculture, refrigeration and
air conditioning, hydrogen production.
• The main challenges include the cost of production,
transportation, and distribution, relative to other energy
sources and fuels.
References
• Fred P. Moore c, Lealon L. Martin, Applied
Thermal Engineering 28 (2008) 1015–1021
• http://www.renewableenergyworld.com/rea/tec
h/oceanenergy
• http://www.nrel.gov/otec/what.html
• http://en.wikipedia.org/wiki/Ocean_thermal_e
nergy_conversion
Thanks For Your Attention