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The plankton ocean digester (POD) provides ecologically sound energy, fresh water, and food production with the carbon sequestering cycle illustrated below. Fresh water, a February 2009 insight - Anaerobic digestion produces the molecules used for forward osmosis, carbon dioxide and ammonia. In reverse osmosis, pressure forces pure water through a membrane excluding salt molecules. The pressure required is proportional to the salt concentration and is known as the osmotic pressure. In forward osmosis, one concentrates molecules that can be removed without significant energy on the “pure water” side of the membrane. When the removable molecule concentration exceeds the salt concentration, the osmotic pressure works to draw pure water through the membrane. Forward osmosis researchers are using carbon dioxide and ammonia for the removable molecules. Carbon dioxide will dissolve in sufficient concentrations for seawater forward osmosis at about 50 atmospheres pressure. Not including the cost of dissolving the initial carbon dioxide supply, the energy cost of recycling and recompressing carbon dioxide in a seawater forward osmosis process is about 0.4 kWh/m3 of fresh water produced. The bacteria in high-pressure anaerobic digestion may produce the dissolved carbon dioxide at the necessary concentration and pressure and avoid the 0.4 kWh/m3 energy cost. Also, a high-pressure anaerobic digestion biomethane production facility would require relatively little additional structure to incorporate forward osmosis seawater desalting. Simultaneously produce: 400 million MWh ( .
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