Blue energy 4711003 222436386 2008-06-29T09:54:46Z Mion 724747 /* Testing */ +restoring PRO capacity {{Renewable energy sources}} '''Blue energy''', '''osmotic power''' or '''salinity gradient power''' is the energy retrieved from the difference in the salt concentration between [[seawater]] and [[Fresh water|river water]]. Two practical methods for this are Reverse Electrodialysis <ref>Power generation by reverse electrodialysis[http://mtg.tnw.utwente.nl/teaching/assign/blue/]</ref> (RED), or Pressure Retarded Osmosis <ref>How does PRO work?[http://www.statkraft.com/pub/innovation/osmotic_power/osmotic_power_in_brief/the_pro_concept.asp] </ref> (PRO). Both processes rely on [[osmosis]] with ion specific [[artificial membrane|membrane]]s. The key waste product is [[brackish water]]. This byproduct is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water. The technologies have been confirmed in laboratory conditions. They are being developed into commercial use in the Netherlands (RED) and Norway (PRO). The cost of the membrane has been an obstacle. A new, cheap membrane, based on an electrically modified [[polyethylene]] plastic, made it fit for potential commercial use <ref>History of osomtic power[http://www.statkraft.com/Images/Faktaark%20OSMOTIC%20ENG_tcm4-7797.pdf]</ref> ==PRO (Pressure Retarded Osmosis)== [[Image:Blue energy mechanism.png|thumb|right|The [[water potential]] between [[fresh water]] (right) and [[sea water]] (left) corresponds to a [[hydraulic head]] of 270 metres]] In PRO, the [[water potential]] between [[fresh water]] and sea water corresponds to a pressure of 26 [[Bar (unit)|bar]]s. This pressure is equivalent to a column of water ([[hydraulic head]]) 270 meters high. <ref>[http://www.statkraft.com/pub/innovation/osmotic_power/osmotic_power_in_brief/osmotic_power_in_brief.asp How does it work?] - [[Statkraft]]</ref> However, the optimal working pressure is only half of this, 11 to 15 bar. <ref>[http://www.tekniikkatalous.fi/doc.te?f_id=993960&plain=true Osmoosivoimalan toiminta] - ''[[Tekniikka & Talous]]'' {{fi icon}}</ref> ==RED (Reverse ElectroDialysis)== In reverse electrodialysis (RED) a salt solution and fresh water are let though a stack of alternating cathode and anode exchange membranes. The chemical potential difference between salt and fresh water generates a voltage over each membrane and the total potential of the system is the sum of the potential differences over all membranes. It is important to remember that the process works though difference in ion concentration instead of an electric field, this has implications for the needed properties for a suitable membrane<ref>[http://mtg.tnw.utwente.nl/teaching/assign/blue/ See note 2]</ref> In RED, as in a [[fuel cell]], the cells are stacked. A module with a capacity of 250 kW has the size of a shipping container. In the [[Netherlands]], for example, more than 3,300 m³ fresh water runs into the sea per second on average. The membrane halves the pressure differences which results in a water column of approx. 135&nbsp;meters. The energy potential is therefore e=[[Potential_energy#Gravitational_potential_energy|mg&Delta;h]]=3.3*10^6&nbsp;kg/s*10&nbsp;m/s^2*135&nbsp;meters ca.= 4.5*10^9&nbsp;Joule, Power=4.5*10^9&nbsp;watt. <!-- These numbers do not work out correctly: see Talk. Theoretically the output is 2.5 MJ or 0.5 kWh/m³. This corresponds to about 3,000 MW, which is about one-third of the national electricity consumption ([[2005]]). --> ==Testing== With RED, in 2006 a 50 kW plant in planned located at a coastal test site in [[Harlingen, Netherlands|Harlingen]], the Netherlands, the focus is on prevention of [[biofouling]] on the [[anode]], [[cathode]] and membranes and increasing the membrane performance <ref> [http://www.netserver2.net/waterforum/index.asp?url=/template_a1.asp&que=paginanr=3716 Friese wereldprimeur met stroomproductie uit zoet-zout water]</ref>. In 2007 the Directorate for Public Works and Water Management, Redstack and ENECO signed a declaration of intent for development of a clean plant in [[Afsluitdijk]] dam in Netherlands [http://corporateuk.eneco.nl/pages/default.asp?PageID=60&Mainmenu=News%20and%20media&MainmenuID=45&Mainmenusub=Press%20releases&MainmenusubID=60&ShowNieuws=13424&ModuleitemID=424]. To start with, the conditions for the construction of an installation in or on the Afsluitdijk dam will be investigated. This study should be concluded by the middle of 2008. Subsequently a small 10-50 kilowatt installation will be built to test the RED technology under actual working conditions. These tests will run from mid 2008 until 2010. After that, the capacity will be expanded to 1000 kW and the system will be optimized. It is to be expected that after this phase the installation will be further expanded to a final capacity of 200 MW. In the case of PRO, [[Statkraft]] in Norway has announced that it will build an osmotic power plant prototype in [[Hurum]] in [[Buskerud]]. The prototype is planned to produce 2-4 kW at the start in 2008. <ref>[http://www.statkraft.com/pro/press/Press_releases/2007/Statkraft_to_build_world_s_first_osmotic_power_plant.asp Statkraft to build world's first osmotic power plant]</ref> <ref>[http://www.nyteknik.se/art/52676 Norway gets the world's first salt power plant]</ref>It is estimated that each year 1600 TWh could be generated world wide, and 12 TWh in [[Norway]], sufficient to meet 10% of Norway's total demand for electricity<ref>[http://www.statkraft.com/pro/press/Press_releases/2007/Statkraft_to_build_world_s_first_osmotic_power_plant.asp Statkraft to build world's first osmotic power plant]</ref>. <!-- [[Eneco Energie]], Redstack and the Directorate for Public Works and Water Management ([[Rijkswaterstaat]]) will construct a small 10-50 kW installation in or on the [[Afsluitdijk]] by the middle of 2008. After 2010 the installation could be further expanded to a final capacity of 200 MW.<ref> [http://corporateuk.eneco.nl/pages/default.asp?PageID=60&Mainmenu=News%20and%20media&MainmenuID=45&Mainmenusub=Press%20releases&MainmenusubID=60&ShowNieuws=13424&ModuleitemID=424 ENECO Press release 'Electricity from fresh and salt water' 2007 November 1th]</ref> --> == References == {{reflist}} *[http://www.wetsus.nl/ Wetsus] *[[KEMA]]/[[VolkerWessels]]/[[Velsen Flexoplast]] *[http://www.kema.com/corporate/news/consulting_services/2004/q2/blue_energy.asp KEMA] *[http://www.onderzoekinformatie.nl/en/oi/nod/organisatie/ORG1241843/ Dutch Research Database] *[http://exergy.se/goran/cng/alten/proj/97/o/ Osmotic Energy (1995)] *[http://www.oceansatlas.com/unatlas/uses/EnergyResources/Background/Salinity/sp1.html Salinity Power UN Report] == Further reading == * {{cite journal|author= Loeb S., Norman R. S.|title= Osmotic Power Plants||journal= Science| year =1975 |pages= 654–655| doi=10.1126/science.189.4203.654|volume= 189}} * {{cite journal|author= Loeb S. |year= 1998| title= Energy Production at the Dead Sea by Pressure-Retarded Osmosis: Challenge or Chimera? |journal= Desalination |volume= 120| pages= 247–262| doi= 10.1016/S0011-9164(98)00222-7}} * {{cite journal|author= Norman R. S.|year= 1974|title= Water Salination: A Source of Energy|journal= Science|volume= 186|doi=10.1126/science.186.4161.350}} * {{cite journal|author=Cath T. Y., Childress A. E., Elimelech M.| title= Forward osmosis: Principles, applications, and recent developments ('''Review''')|journal= Journal of Membrane Science||volume= 281|pages=70–87|year= 2006| doi= 10.1016/j.memsci.2006.05.048}} * {{cite journal|author= Loeb S.| title= Comments on the suitability of reverse osmosis membranes for energy recover by submarine osmotic power plants Desalination ('''Review''')|journal= Journal of Membrane Science||volume= 68|pages=75–76|year= 1988| doi= 10.1016/0011-9164(88)80044-4}} * {{cite journal|author= Loeb S.| title= Large-scale power production by pressure-retarded osmosis, using river water and sea water passing through spiral modules desalination ('''Review''')|journal= Journal of Membrane Science||volume= 143|pages=115–122|year= 2002| doi=10.1016/S0011-9164(02)00233-3}} ==See also== {{EnergyPortal}} {{Portal|Sustainable development|Sustainable development.svg}} *[[Electrodialysis reversal]] (EDR) *[[Reverse osmosis]] *[[Semipermeable membrane]] *[[Green energy]] *[[Renewable energy]] {{FuelCellGroup}} [[Category:Fuel cells]] [[Category:Sustainable technologies]] [[Category:Alternative energy]] [[Category:Energy conversion]] [[da:Saltkraft]] [[de:Osmosekraftwerk]] [[es:Energía azul]] [[id:Sumber energi osmosis air]] [[it:Energia blu]] [[nl:Blauwe energie]] [[no:Saltkraft]] [[nn:Saltkraft]] [[pt:Energia azul]] [[sv:Saltkraft]]