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Energy Quote

The world is full of tradeoffs, and sometimes 'renewable power' activists fail to recognize that. Solar energy collectors must displace a tremendous amount of natural landscape to produce any significant amount of energy. And anything less requires a great deal of financial expenditures for very little and very inconsistent power.

Ben Lieberman

Salinity Gradient Power

A Brief Description:

Salinity Gradient is a technology that takes advantage of the osmotic pressure differences between salt and fresh water or water of different salinity. Salinity gradient power is completely renewable and sustainable. It is the highest energy concentration (i.e., energy density) of all marine renewable energy sources, an ultra-dense energy resource. Despite its potentilality, salinity gradient energy is often-overlooked source of marine renewable energy.

Various concepts on how to make use of salinity gradient power were proposed more than twenty years ago. One such concept is the Pressure-Retarded Osmosis (PRO). In PRO, seawater is pumped into a pressure chamber where the pressure is less than the osmotic pressure difference between fresh water (or low salinity water) and seawater (or higher salinity water). Freshwater flows through a semipermeable membrane and increases the volume (or pressure) within the chamber; a turbine is spun as the pressure is compensated.

Early technical advances were not considered promising, mainly because they relied on expensive membranes. Membrane technologies have advanced, but to date, they remain the technical barrier to economical energy production. Efforts are underway to address those issues and alternatively develop designs that eliminate membrane. The alternative technologies include vapour compression and the patented hydrocratic generator

31 Jan 2007 10:45:10

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