pressure retarded osmosis
TRANSCRIPT
PRESSURE RETARDED OSMOSIS
By: Matthew FenechSubject: Alternative Power GenerationLecturer: Ing.T. Darmanin
Ocean Technology
• Tidal Energy; Abundant but Untameable!
– Unpredictable
– Requires large control effort
• Calmer Waters are also abundant in energy
– Osmosis is the key!
– Dealing with forward osmosis (not reverse)
Theory of Operation• Osmotic Power, “A pressure that must be applied
to the solution (sea water) to just prevent osmotic flow”
• Harnessing energy where river freshwater and seawater meet
• Seawater is pumped into a pressure exchanger where the osmotic pressure is less than that of the freshwater pressure
Theory of Operation
• Freshwater(solvent) flows through the semi-permeable membrane towards the seawater (solute) chamber and increases the mass and volume (Δh)
– But Why? Water flows from a lower concentration to a higher concentration to equalize the concentration levels
– Semi-permeable inhibiting salts to pass through the fresh water side
• The head that is generated where generally heads of 120 - 270m (26Bar) are reached
• Compared to a waterfall head, for hydro-power generation (Fernanda Helfer, N/D)
History of Pressure Retarded Osmosis
• 1954, Pattle published free-energy acquisition via freshwater and saltwater mixing
• 1973, interest in technology reemerged due to oil crisis
• 1975, PRO was first invented by Prof. Sidney Loeb & Osmotic Heat Engine
• 2006, Starkraft (Norway) developed the first PRO powerplant generating 10KW
(Andrea Achilli, 2010)
Pressure Retarded Osmosis
Technology
• “The Energy Released from the mixing of freshwater with saltwater”
• Salinity gradient power is the energy created from the difference in salt concentration between two fluids, fresh & salt water.
• Applications:
– Standalone power plants
– Hybrid power plants
Pressure Retarded Osmosis
Technology
• Main Components
– Pumps
– Stacks of Semi-permeable membrane, Hollow Fibre Membranes, generating 4.4W/
– Pressure Exchanger, energy recovery system
– Piping Network
– Hydro-Turbine
– Generator
Geographical Power
Generation
(Irena, 2014)
Economics
• Membranes account up to 80% of capital costs
– EUR10/ -> EUR30/
– To be competitive (with other renewables) must be dropped down to EUR2/ -> EUR5
• For a 2MW plant, 2million of membranes are required
• Cost projections for 2020 EUR0.08/KWh to EUR0.15/KWhr
(Irena, 2014)
Drivers and
Barriers
+ Emission Free power generation
+ It is alternative and sustainable
‒ Biological Fouling due to microorganisms
‒ Excessive capital costs‒ Membrane lifetime, 5 years
‒ Ecological Aspects; River deviations
‒ Environmentalists unrest
Conclusion
• Infant technology
• Other Salinity Gradient Technology
– Reversed Electro Dialysis (RED)
– Osmotic Heat Engine
• Future trends…
Questions?
References
• Andrea Achilli, A. E. (2010). Pressure retarded osmosis: From the vision of Sidney Loeb to the first prototype. Nevada: Elsevier.
• Fernanda Helfer, C. L. (N/D). Osmotic Power with Pressure Retarded Osmosis: Theory, Performance and Trends – a Review. Southport.
• Irena. (2014). Salinity Gradient Energy, Technology Brief. IRENA (International Renewable Energy Agency).