Ocean Farming Research Articles

The ocean as a supplier of food and energy

This paper presents the concept of raising seaweeds and other valuable organisms with the aid of huge structures (‘ocean farms’) emplaced in the surface waters of the open oceans. Potential advantages from and difficulties to be expected in realizing the associated technologies are briefly set forth. Much of the published literature pertaining to the concept is referenced and summarized. Wave-powered upwelling of cool, nutrient-rich waters through vertical pipes extending to depths of 100–300 m is indicated as desirable. Technologies are outlined for using the harvested seaweeds to create foods and other valuable products such as animal feeds, fertilizers, fibers, plastics, synthetic natural gas (methane), and alcohol and gasoline fuels. Results from site selection studies and economic analyses are given. It appears that dynamically positioned farms orbiting with the surface current patterns typically found on the ocean will be most cost-effective. The general conclusion is stated that open ocean farming will become economically more feasible as the cheaper fossil fuels and food producing lands of the earth become increasingly consumed in the course of the next century.

Dewatering Kelp for Fuel, Feed, and Food Uses: Process Description and Material Balances

ADSTRACT THE Ocean Food and Energy Farm Project envi-sions using Macrocystis pyrifera (giant kelp), grown in vast ocean farms, as a source of a fermentable material for producing a substantial portion of our nation's fuel gas and as a source of animal feed and/or human food. However, the high ash content of kelp may be inhibitory or toxic to anaerobic fer-mentation and may limit the proportion of kelp in animal feeds. A process has been developed by the Western Regional Research Center which reduces the ash and water content of kelp and increases its caloric and bulk densities. In a typical example, kelp is treated with CaCl2, heated, and pressed to remove 75 percent of the moisture and 65 percent of the ash initially present; 70 percent of the organic solids are retained for fermentation. Technical feasibility of the process has been demonstrated in pilot-plant testing using com-mercially available equipment.

Oceanexpo–Offshore

Oceanexpo—Offshore ′74, the Second International Conference and Exhibition on Ocean Farming and Industrial Offshore Techniques, will be held in Bordeaux. France, from October 1 to 6, 1974.As in 1971 Oceanexpo—Offshore will bring together several exhibitions, such as an international exhibition of ocean equipment; a working demonstration of marine and submarine engines and equipment; an international scientific and technical conference; and an industrial film festival on ocean farming and offshore techniques.

Flow estimate for the perpetual salt fountain

STOMMEL et al. (1955) pointed out the perpetual salt founta as an interesting oceanographical curiosity that might possibly be used for pumping up nutrient-rich deep water to the surface for ocean farming applications. The fountain would work in a region where there is a salinity minimum below the warm surface layer of the ocean. STOMMEL et aL state, If a long tube were lowered from the surface to depth of low salinity water, and the deep water were slowly pumped to the surface through the tube, and the pump then disconnected, the water would continue to flow, by itself, forever. This remarkable phenomenon occurs because slow motion through the tube allows the water inside to attain the same temperature as the surrounding water. Its salinity, and hence density, is therefore less than that of its surroundings outside the tube, and hence the entire column of water inside the tube is buoyant with respect to the fluid outside at the same level. If the direction of pumping is reversed, so that the fluid initially goes downward, it will of course continue to flow downward forever on account of its excess in density over that of the water outside the tube. In order to estimate the rate of flow in the salt fountain, let us assume that a straight tube of length L extends slanting from the surface to a depth h in a horizontally stratified ocean. The vertical co-ordinate y is taken positive downward and zero at the surface, and 0 (y) and S (y) represent the temperature and salinity, respectively, of the ocean. Inside the tube the salinity is uniformly equal to S (h) for upward flow and the temperature is designated by 4' (Y), steady state being assumed. Taking the temperature inside the tube as a function only of y presupposes complete mixing in any horizontal layer and leads to a slight over-estimate of heat conduction and hence flow rate especially in the case of laminar flow, but this will not seriously affect the results. The water density inside and outside the tube is taken as a linear