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Batteries for Efficient Energy Extraction from a Water Salinity Difference

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journal contribution
posted on 13.04.2011, 00:00 authored by Fabio La Mantia, Mauro Pasta, Heather D. Deshazer, Bruce E. Logan, Yi Cui
The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called “mixing entropy battery”, which can extract and store it as useful electrochemical energy. The battery, containing a Na2−xMn5O10 nanorod electrode, was shown to extract energy from real seawater and river water and can be applied to a variety of salt waters. We demonstrated energy extraction efficiencies of up to 74%. Considering the flow rate of river water into oceans as the limiting factor, the renewable energy production could potentially reach 2 TW, or ∼13% of the current world energy consumption. The mixing entropy battery is simple to fabricate and could contribute significantly to renewable energy in the future.