45 



The design consisted of an open ocean farm covering 100,000 acres, 12.5 miles on a 

 side, located 100 miles off the coast of Southern California. Following site survey 

 studies, 3 sites in Southern California were recommended. The farm substrate, 

 maintained at a depth of 34 meters was to be made up of flexible triangular moduls, 

 1,000 feet on a side each covering about 10 acres. Each module would be held in 

 place by diesel-powered propulsors. Nutrient-rich water was to be upwelled from a 

 depth of about 91 meters by wave-powered pumps. 



Kelp plants, attached to the substrate at a density of one plant per 34 square 

 meters, would take about 4 years to mature and then the standing crop would be 

 harvested by a harvesting ship six times per year. The estimated yield of the farm 

 was about 15 dry tons/acre/year of which eight tons would be organic biomass. In 

 comparison, the productivity of natural kelp beds is estimated by Dr. Wheel North 

 and others as 1-2 tons/acre/year. 



To test the technical and economic feasibility of the commercial-sized ocean 

 energy farm, a research program was initiated in 1976 jointly sponsored by ERDA 

 (subsequently DOE) and the American Gas Association and managed by the General 

 Electric Company. Scientific and engineering support is provided by the Institute of 

 Gas Technology, the U.S. Department of Agriculture and Global Marine Develop- 

 ment, Inc. Under this program a quarter acre module (QAM) of the sea farm was 

 constructed at a site off Laguna Beach, CA. The QAM consisted of 8' diameter buoy 

 which stands upright in the water and is attached by a swivel joint to an umbrella- 

 shaped set of radial arms to which kelp plants are attached. Nutrient-rich water is 

 pumped up through 2' diameter fiberglass pipe using 3 pumps of 3,300 GMP driven 

 by a 35 HP diesel. The test farm was deployed at sea in 1978, and soon thereafter 

 was seeded with juvenile kelp plants, but due to a number of technical problems, 

 the initial plantings failed to survive. A second test of the experimental system was 

 in preparation at the time this article was written. In the meantime, a DOE- 

 sponsored engineering and economic analyses of a number of proposed aquatic 

 biomass energy farms, including both freshwater and marine species and unicellular 

 algae as well as seaweeds and higher plants, carried out by Dynatech R/D Company 

 of Cambridge, MA cast some considerable doubt on the cost-effectiveness of the 

 proposed kelp farm both with respect to economics and the energy input:output 

 ratio. 



Seaweed culture as a large-scale commercial operation is still very much in its 

 infancy. The few practices scattered around the world are, for the most part, 

 primative and make little use of modern technology. Much remains to be learned 

 about the basic biology of the plants, particularly with respect to their nutrition and 

 growth and factors that control their organic productivity. The much more difficult 

 task of developing a technology for growing seaweeds in the open sea must await 

 our ability to grow them in small, controlled experimental units on land or in 

 protected coastal areas, and to fully understand and define their growth potential 

 under different conditions. In short, open-ocean energy farming of seaweeds must be 

 regarded as a long-term prospect that cannot be expected in a time frame of less 

 than tens of years. 



It would be a serious mistake to neglect the challenging potential of producing 

 biomass from the open sea. But it would be equally wrong, in my opinion, to plunge 

 headlong into large-scale and costly experiments in this area where so much funda- 

 mental science and technology remains to be done. Repeated failure of such hastily 

 conceived efforts will lead inevitably to the premature elimination of open-ocean 

 energy farms from further consideration. That would be unfortunate, because the 

 ocean is just about the only place on earth where truly large-scale biomass produc- 

 tion, capable of contributing significantly to the world's energy budget on a non- 

 competitive basis with man s other space needs, could conceivably be carried out. 



High-yielding terrestrial and aquatic crops 



[Units in dry weight tons per acre per year] 



Experimental (small scale, maxima): 



Sugar cane (Puerto Rico) 22 



Napier grass (Puerto Rico) 26 



Water hyacinth (Florida) 35 



Gracilaria (Florida) 52 



Commercial (large scale, average): 



Silviculture (U.S.) 10 



Sugar cane (Hawaii) 16 



Sugar cane (Mainland U.S.) 10 



Corn (U.S.) 5 



Kelp (People's Republic of China) 20 



Gracilaria (Taiwan) 6 



