OCEAN ENERGY! A COMPREHENSIVE SOLUTION TO ENERGY CRISIS
Uploaded by vikalpchauhan on Nov 18, 2017
BLUE ENERGY! A COMPREHENSIVE SOLUTION TO ENERGY CRISIS
Abstract- The possibility of osmotic energy for energy crisis as a solution lies within the technology that needs to be developed further. Osmosis & RED have been discussed for power generation by mixing of fresh & saline ocean water. Efforts have been made to bring blue energy as renewable energy source even if it is only a partial solution to energy & environmental problems.
Keywords:-Osmosis, RED (Reverse Electro Dialysis), Hypolimnion
1. INTRODUCTION TO BLUE ENERGY
The need of new energy sources leads to energy created by transportation of solutions, osmotic energy & salient gradient energy. Salination would be a perfect technique for places where fresh & ocean water mixes naturally.[1]Idea of producing blue energy was explored during energy crisis of 1970’s.Energy released by world’s fresh water rivers flowing into salty oceans is compared to each river ending at its mouth in a waterfall of 739 feet high. With development of membrane technology & electrical modifications of plastics, semi-permeable membranes have been developed to use osmotic effect & RED along with its conversion to mechanical energy.
2. ELECTROLYSIS CONCEPTS
I. OSMOSIS
Osmotic energy is the transportation of pure water & salt water separated by a semi-permeable membrane which is an organic filter with extremely small holes for passage of water molecules. Water aspires to decrease the salt concentration on the side of membrane having most of salt. Water streams through the membrane & creates pressure on other side which is used to gain blue energy by using a turbine & generator.[2] Fig1 shows a test rigg for osmosis process where semi-permeable membrane separates pure water & a solvent with water & salt (NaCl).
Fig. 1: Test rigg for osmosis process
The amount of fresh water passing through membrane depends on salt concentration in salt water. For concentration of 3.5%, osmotic pressure is approx. 26 bars.[3]. Demerit is that with reduced salt concentration in salt water, process slows down. To fix it, both sides must be empty & refill very quickly to avoid run-interference. Membrane wears out because of silt & contaminations getting stuck. Life of membrane gets reduced to approximately 5 months.
II.REVERSE ELECRO DIALYSIS (RED)
Concentrated salt solution & fresh water phase are brought into contact through alternating series of anion & cation exchange membranes. Anions migrate through anion exchange membrane towards anode & cations move through cation exchange membrane towards cathode thereby creating a potential difference. Pressure larger than osmotic head...