Ocean thermal energy conversion material requirements for large-Scale systems
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AND W. E. HERONEMUS
T h i s p a p e r s u m m a r i z e s the g e n e r a l c o n c e p t s and c u r r e n t s t a t e - o f - t h e - a r t for O c e a n T h e r m a l E n e r g y C o n v e r s i o n (OTEC) S y s t e m s , a l a r g e - s c a l e s o l a r e n e r g y d r i v e n r e s o u r c e . S p e c i f i c a l l y , it f o c u s e s on the v a r i e d m a t e r i a l n e e d s for such p o w e r p l a n t s . E a c h of the s y s t e m ' s m a j o r c o m p o n e n t s (turbine, heat e x c h a n g e r , o c e a n p l a t f o r m o r hull, and o c e a n w a t e r d e l i v e r y s y s t e m ) is d i s c u s s e d with r e s p e c t to m a t e r i a l r e q u i r e m e n t s (type and magnitude) n e e d e d for the v a r i o u s d e s i g n s . The heat e x c h a n g e r s a r e c o n s i d e r e d to be the key p o w e r plant c o m p o n e n t s and v a r i o u s d e s i g n s and m a t e r i a l c h o i c e s a r e p r e s e n t e d . A l s o , the i m p a c t on m a t e r i a l r e s o u r c e s for l a r g e - s c a l e i m p l e m e n t a t i o n of such s y s t e m s is c o n s i d e r e d .
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p a s t five y e a r s the c o n c e p t of l a r g e s c a l e e n e r g y c o n v e r s i o n via the s o l a r e n e r g y c o l l e c t e d f r o m the w o r l d ' s o c e a n s has b e e n u n d e r s e r i o u s inv e s t i g a t i o n . 1 As shown in T a b l e I, 2 a s a r e s u l t of t h e s e O c e a n T h e r m a l E n e r g y C o n v e r s i o n (OTEC) s t u d i e s , this type p o w e r g e n e r a t i o n s y s t e m h a s m o v e d into c o m p e t i t i o n with o t h e r p r o p o s e d s o l a r e n e r g y s y s t e m s . T h i s s y s t e m (shown in F i g . 1) m a k e s use of a R a n k ine C y c l e coupled with hot and cold w a t e r p u m p i n g s y s t e m s to p r o d u c e u s e f u l p o w e r . In c o n t r a s t to c o n v e n t i o n a l p o w e r p l a n t s with t h e i r c o m p l e x Rankine C y c l e s , this s y s t e m u s e s a s i m p l e c y c l e with only f o u r m a j o r c o m p o n e n t s ( e v a p o r a t o r , t u r b i n e , c o n d e n s e r , and w o r k ing fluid p u m p s ) . Due to the s m a l l t e m p e r a t u r e diff e r e n c e s a v a i l a b l e , a l l the s y s t e m d e s i g n s to d a t e have low t h e r m a l e f f i c i e n c i e s (2 to 3 pct) which d i c t a t e s that d e t a i l e d a n a l y t i c a l s t u d i e s m u s t be c a r r i e d out to m i n i m i z e the s y s t e m l o s s e s and r e d u c e t h e i r c a p i t a l c o s t s . O u r w o r k a t the U n i v e r s i t y of M a s s a c h u s e t t s d u r i n g the p a s t five y e a r s h a s c o n c e n t r a t e d on O T E C p o w e r s y s t e m s , and h a s p r o d u c e d s e v e r a l d e s i g n s , one of which is in F i g . 2, f o r the Gulf S t r e a m b a s e d s y s t e m . 3 At the s a m e t i m e two i n d u s t r i a l g r o u p s l e a d by TRW and L o c k h e e d have d e v e l o p e d s y s t e m d e s i g n s f o r OTEC p o w e r p l a n t s .
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