Food/Open ocean farms

69% of the planet is ocean; if we can effectively farm this area, there can be no scarcity of food.

Open ocean farming is currently being researched by several companies and universities. Floating nets are used to grow edible seaweeds ("sea vegetables"), and floating or submersible cages are used to breed fish in. As with all water-based agriculture, the plants grow about 10 times faster than with land-based agriculture. Inedible seaweeds can converted efficiently into edible fish; 4 tons of seaweed feed will typically yield 3 tons of fish. Seaweed also makes good fertilizer for land-based growing.

This presentation from researchers at Wageningen University calculates that less than 240,000km² of open ocean farms worldwide would provide all the protein needs for 9.3 billion people. This is a modest amount of space to dedicate to ocean farming; it is about the size of Madagascar and could be spread across offshore areas near population centres. (Most people live near coasts.) Realistically, ocean farms will be only one of several protein sources, so this large an area will not be necessary.

• Ocean Farm Tech use floating geodesic spheres that hold fish inside
• Ocean Harvest Technologies grow seaweed on floating nets
• http://oceanfarmtech.com/news.htm - lots of links
• http://www.openblueseafarms.com/who_we_are/our_company.html