Blue energy

Blue energy is the energy retrieved from the difference in the salt concentration between seawater and river water with the use of reverse electrodialysis (RED) (or osmosis) with ion specific membranes. The waste product in this process is brackish water.

The technology of reversed electrodialysis has been confirmed in laboratory conditions. As in common technologies, the cost of the membrane was an obstacle. A new, cheap membrane, based on an electrically modified polyethylene plastic, made it fit for potential commercial use.

The water potential between fresh water and sea water corresponds to a pressure of 26 bars. This pressure is equivalent to a column of water 270 metres high.^[1] However, the optimal working pressure is only half of this, 11 to 15 bar.^[2]

In the Netherlands, for example, more than 3,300 m³ fresh water runs into the sea per second on average. The energy potential is therefore 3,300 MW, based on an output of 1 MW/m³ fresh water.

The water potential between fresh water and sea water corresponds to a hydraulic head of 270 metres

Size

As in a fuel cell, the cells are stacked. A module with a capacity of 250 kW has the size of a shipping container.

Testing

2005 A 50 kW plant is located at a coastal test site in Harlingen, the Netherlands. The focus is on prevention of biofouling on the anode, cathode and membranes and increasing the membrane performance.

Statkraft in Norway has decided to build a osmotic power plant prototype in Hurum in Buskerud. The prototype is planned to produce 2-4 kW at the start in 2008.^[3]

See also

• Electrodialysis reversal (EDR)
• Reverse osmosis
• Semipermeable membrane
• Green energy
• Renewable energy

References

• KEMA/VolkerWessels/Velsen Flexoplast
• KEMA
• Wetsus 1
• Wetsus 2
• Wetsus 3 specific page
• Osmotic Energy (1995)
• Salinity Power UN Report
• Norway gets the worlds first salt power plant
• Statkraft builds the worlds first salt power plant

Further reading

• Loeb S., Norman R. S. (1975). "Osmotic Power Plants". Science 189: 654-655. DOI:10.1126/science.189.4203.654. 
• Loeb S. (1998). "Energy Production at the Dead Sea by Pressure-Retarded Osmosis: Challenge or Chimera?". Desalination 120: 247-262. DOI:10.1016/S0011-9164(98)00222-7. 
• Norman R. S. (1974). "Water Salination: A Source of Energy". Science 186. DOI:10.1126/science.186.4161.350. 
• Cath T. Y., Childress A. E., Elimelech M. (2006). "Forward osmosis: Principles, applications, and recent developments (Review)". Journal of Membrane Science 281: 70-87. 
• Loeb S. (1988). "Comments on the suitability of reverse osmosis membranes for energy recover by submarine osmotic power plants Desalination (Review)". Journal of Membrane Science 68: 75-76. DOI:10.1016/0011-9164(88)80044-4. 
• Loeb S. (2002). "Large-scale power production by pressure-retarded osmosis, using river water and sea water passing through spiral modules desalination (Review)". Journal of Membrane Science 143: 115-122. DOI:10.1016/S0011-9164(02)00233-3. 

Donate to Wikimedia