Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://zebu.uoregon.edu/1998/ph162/l15.html
Дата изменения: Tue May 19 20:39:43 1998 Дата индексирования: Tue Oct 2 00:33:19 2012 Кодировка: Поисковые слова: р с р р р р р с с с р р р р с р р с р |
More promising technology is OTEC (Ocean Thermal Energy Generation). This takes advantage of the fact that the ocean is an enormous heat engine.
Physics of Heat Engines:
T = 373K
T=273K
T=77K
To get the highest efficiency one wants to maximize the difference between T1 and T2 but then their are material problems (containers melt, freeze, etc)
Typical Case:
How this all works:
Heat Energy from the Ocean
Do this:
Basic principle is that heat difference is used to condense a steam into a liquid then return it to be reheated.
Since heat differences in the ocean will be smaller, then one must substitute ammonia for water as the working fluid.
Example Calculations:
Above sites typically have thermal gradients higher then 22 degrees C
Energy extracted comes from the cooling of the warmer water
this is transferred to the ammonia which does the actual work
of turning the turbine (as ammonia steam)
Energy extracted proportional to the volume of water and the temperature it drops.
Principal energy loss is when the warmer water meets the cooler water in the condenser.
Review of OTEC (Ocean Thermal Energy Conversion)
Ocean Power also comes in 2 other forms:
The ocean is a huge reservoir for storing the energy of the sun that is incident on the earth. How huge is huge?
Incident flux on ocean surface area is 1017 Watts or 0.1 Billion Billion Watts (its a large number)
The oceans are a huge heat engine. Temperature differences, caused by differences in insolation both in latitude and in depth.
Tapping the Current for Energy:
Extracts energy from the kinetic energy of the earth-moon-sun system.
Variations in water level along coastlines can be used to drive
turbines technology is the same as low-head hydro power
Vertical tides on US coast range from 2 feet in Florida to more than 18 feet in Maine
To enhance efficiency of turbines driven by tidal currents, it is desireable to build a damlike structure across the mouth of a tidal basin in order to direct the flow to a turbine
Turbines designed for work at both high and low tide (inflow or outflow)
Intermittent tidal flow is major problem. Tidal facility produces about 1/3 the electrical energy of a hydro facility of the same peak capacity
Two tidal plants in the world:
Proposed New Facilities:
Potential Sites in the US
Bottom Line: There aren't many favorable sites in the world for tidal power and the estimated capacity is 50 times smaller than the world's hydroelectric power capacity.