OSMOTIC POWER

Submitted By,Snehitha Bolla(2619442)Raja Sandeep (2660330)

OUTLINE Motivation Introduction Osmosis Osmotic power Principle Pressure retarded

osmosis (PRO) Construction

Components Operation Experimental results Advantages Disadvantages Future scope Conclusion

MOTIVATION Non conventional power

in various sources is effected predominantly by climatic conditions and cannot be operated throughout the year.

Need for development of new type of non conventional power that can be operated 24/7 and that is osmotic power.

First osmotic power plant is built in Tofte, Norway in 2009.

INTRODUCTION Osmotic power is energy available from

difference in salt concentration between sea water and river water.

It is huge and unique energy source. Renewable energy source that converts

pressure differential between water with high salinity and water with lower or no salinity in to hydraulic pressure.

Fresh water moves by osmosis through membrane in to sea water.

OSMOSIS Physical process in

which solvent moves across semi permeable membrane separating solutions of different concentrations.

Osmosis is vital process in biological systems as biological membranes are semi permeable.

Before Osmosis After Osmosis

Osmotic pressure: Minimum pressure that should be applied to

a solution to prevent inward flow of water across semi permeable membrane.

Measure of tendency of solution to take in water by osmosis.

Potential osmotic pressure: Maximum osmotic pressure that can be

developed in a solution if it were separated from fresh water by a selective permeable membrane.

OSMOTIC POWER

RESULTS

Conclusion

PRINCIPLE Osmotic power is

generated by pressure retarded osmosis (PRO).

Technique to separate solvent (fresh water) from a solution that is more concentrated (sea water) and also pressurized.

Turbine

PRESSURE RETARDED OSMOSIS It relies on water molecules moving through

a semi permeable membrane. Semi permeable membrane allows solvent

(fresh water) to pass to the concentrated solution (sea water) side by osmosis.

This technique can be used to generate power from salinity gradient energy resulting from the difference in salt concentration between sea water and river water.

Output is proportional to the salinity.

CONSTRUCTION

Fig: Commercial Setup for Osmotic Power Generation

COMPONENTS1. A semi permeable membrane contained

in modules.2. Fresh water and sea water filters that

optimize membrane performance.3. A turbine that generates a driving force

based on osmotic pressure and permeation flow rate.

4. A pressure exchanger that pressurizes sea water feed required to maintain high salinity levels downstream from membrane.

OPERATION

Fig: Operation of Osmotic power

OPERATION Fresh water and sea water sent into two

different modules.

The two modules are separated by a semi-permeable membrane.

The Fresh water seeps through the semi-permeable membrane to the Salt water side.

This increases pressure on the salt water module.

OPERATION The salt water flows

through the turbine which in turn generates electricity.

The brackish water is sent out to the sea.

The high pressure salt water is again sent to the modules through a pressure exchanger.

Fig:Francis Turbine(Cortesy: www.Google.com)

EXPERIMENTAL RESULTS

Fig: Plot to describe salt water pressure for the flow of water

EXPERIMENTAL RESULTS

Fig. Power production from prototype membranesTFC: Thin film membrane composite;

CA: Asymmetric Cellulose Acetate

EXPERIMENTAL RESULTS

Fig: Results for maximum power density (Wmax)

EFFICIENCY The efficiency of this Osmotic power is

91.0%.

The Efficiency(Npx) of the Osmotic power is given by the above expression.

Emech,salt is the energy potential of salt water. Emech,brackish is the energy potential of fresh water.

ADVANTAGES Steady, predictable output.

Adaptable for small or large generating stations.

Scalable or modular design (membrane modules added as required), making it possible to increase installed capacity.

Generating sites near load centers, limiting power transmission needs.

Good potential for power plant sites.

ADVANTAGES & DISADVANTAGES Technology similar and complementary to

that of hydro-electric power, with osmotic power plants able to be built on already-harnessed rivers.

High risk of clogging and gradual degradation of semi-permeable membranes, necessitating pressure-filtering pretreatment of fresh water and periodic membrane re-placement (every 5 to 7 years)

CONCLUSION An analysis of the PRO processes for energy

production from mixing of freshwater and seawater has been performed at realistic conditions for physical plant operation.

A freshwater utilization efficiency of 40% of the maximum mixing energy of freshwater with sea water.

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