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Directory:Mixing Sea and River Water

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Devices based on a natural process -- when a river runs into the ocean, a huge amount of energy is unleashed because of the difference in salt concentration.

Salt Water + Fresh Water Mixed = Energy

Think of it as the oposite of desalination, where: Salt Water + Energy --> Fresh Water (+Salt)

Contents

About

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 electro dialysis (RED) (or osmosis) with ion specific membranes." [1]

Overviews

  • Salt could shake up world energy supply - Two small projects to mix sea and river water seek to capture the energy released when fresh and salt water are mixed, build on knowledge that has been around for centuries -- in one case imitating the process of osmosis used by trees to suck water from their roots. The technology is still far from being economically viable. (WBCSD; Mar. 19, 2008)

Projects

Norwegian project

  • http://www.sintef.no/ - Norway’s independent research organisation SINTEF, working with power company Statkraft started in the 1990s and its creators have already installed two small-scale plants, but have yet to build a bigger demonstration plant to boost production
  • Osmotic Power Plant Set To Open - Norway has announced the opening of the world’s first osmotic power plant, due to begin operations on November 24, 2009. This prototype plant by Statkraft will demonstrate the potential commercial feasibility of the technology the uses the differential between the incoming fresh water and the salt water to cause water to climb against an osmotic gradiant then turn a turbine.. (Alt Energy News; Nov. 4, 2009)
  • Statkraft to build world's first osmotic power plant - Osmotic power, feasible where fresh waters meet salty, could contribute around 1,600 TWh on a global basis annually. First plant, by Norwegian company, putting out just 2-4 kW, is expected by the end of 2008. The technology could become competitive within a decade. (PESN; Oct. 7, 2007)

Wetsus project

set-up.jpg

Dutch Centre for Sustainable Water Technology or Wetsus

supported by a consortium of Dutch companies

have still a long way to go before they can be applied commercially

Penn State

  • Mixing Fresh and Salt Water / Microorganisms > BioElectricity >
    Unique salt allows energy production to move inland - Production of energy from the difference between salt water and fresh water is most convenient near the oceans, but now, using an ammonium bicarbonate salt solution, Penn State researchers can combine bacterial degradation of waste water with energy extracted from the salt-water fresh-water gradient to produce power anywhere. (Energy-Daily; March 5, 2012)

How it Works

Source: http://msnbc.msn.com/id/10463585/

The Dutch apply something called reverse electrodialysis while the Norwegians use a kind of osmosis.

Both methods rely on membranes or thin films made of special material used for chemical separation. In the Dutch project, separation is done by membranes using an electrical current.

It works like a water battery.

The Norwegian device applies pressure to force the water through membranes.

The principle behind the Norwegian device is that fresh water and salt water are channelled into a membrane module. The fresh water is transported through the membranes and over into the pressurised sea water. The pressurised mixture of sea water and fresh water flows out of the module and into a hydropower turbine that generates electricity.


Cost

Power produced by mixing sea with river water is several times more expensive than wind or solar energy. (Ref)

History

The idea of producing electricity from salt and fresh water was first explored during the energy crisis of the 1970s, but membrane technology was not sufficiently advanced and scientists dismissed the process as hopelessly expensive. The membrane industry has matured since then and is now widely used in water and pollution treatment, power generation, production of medical, biotech and electronics devices. (Ref)

Potential

The production potential in Europe is estimated at 200 terawatt hours a year, or nearly twice the electricity consumption of a country like Norway. The potential in Norway alone is estimated at 10 percent of its annual power needs. The river Rhine, for instance, could deliver 3,000 megawatts of power where it flows into the sea in the Netherlands -- the equivalent of five big coal-fired plants. (Ref)

Companies

  • KEMA - ‘Blue energy’ is electricity produced by harnessing the difference in salt concentration between fresh water and salt water. Thanks to advances in the electrical modification of plastics, the special membranes needed for blue energy can now be made very cheaply, which means blue energy has become affordable for countries with river deltas.
  • RED Stack - RED: Reverse Electro Dialysis – Stack: operating membrane and electrode unit - Developing a power plant based on mixing sea/river water to harness the energy in different salt concentrations. Hopes to reduce the current production cost of 1.40 €/kWh to 0.14 €/kWh by 2010 and to design and build a 200 MW power plant.


Research and Development

  • Electricity from salt-fresh water mix - The amount of energy available where fresh water meets salt water is equivalent to a waterfall 225 meters [739 feet] high. An Italian physicist has come up with a 'salination cell' that relies on two chunks of activated carbon, a porous carbon commonly used for water and air filtration. Once jump started with electricity, a continuous flow of water keeps it running. (Physics Central; July 23, 2009)

In the News

  • River runs through this energy source - European researchers are working on ways to generate electricity based on the principle that when a river runs into the ocean, a huge amount of energy is unleashed because of the difference in salt concentration. (MSNBC; Jan. 3, 2006)

Comments

See Discussion page

See also

WATER FOOTER

OBTAINING WATER

ENERGY FROM THE MOVEMENT OF WATER

WATER AS FUEL

OTHER ENERGY TECHNOLOGIES INVOLVING WATER

POLLUTION

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