Background

The U.S. Navy researched an approach to growing kelp in the open ocean.  In the early 1970s, Dr. Howard A. Wilcox of the U.S. Navy first proposed that farming kelp in the open ocean could provide relatively inexpensive energy.1  Due to the oil embargos of the period, the U.S. Navy was researching alternative domestic sources as a national security issue. Working with renowned kelp expert Professor Wheeler North of Caltech and with funding from the Energy Research and Development Agency (ERDA, forerunner of the Department of Energy), the U.S. Navy, the National Science Foundation, and the American Gas Association, Dr. Wilcox developed the concept that giant kelp can convert over 1% of the incident sunlight into useful stored chemical energy, fertilized by nutrients actively upwelled from the depths.

Giant kelp, Macrocystis pyrifera, La Jolla, California, USA, Licensed from Phillip Colla Photography

Most of the well-lit surface of the oceans is a nutrient “desert”, devoid of major macroscopic plant production because the surface waters are nutrient-poor.  Deeper, colder waters are nutrient-rich.  Often there is an abrupt transition that occurs as deep as 300 meters (but often much shallower) between the warmer, nutrient-poor surface waters and colder, nutrient-rich, deeper waters.  Dr. Wilcox proposed large farms – typically 100,000 acres each – that would consist of a huge “net” of ropes to which the kelps would be affixed.  Deep water would be pumped up from a depth of 300 meters to provide nutrients.  Dr. Wilcox calculated that the cost of the rope substrate would be much too large if the farms were anchored to the bottom and had to withstand the forces of currents, waves, and storms.  Instead, he envisioned farms that floated freely and used propulsion systems to give modest control actions sufficient to keep them circulating around the large eddy patterns in the oceans, such as those between California and Hawaii. 

A major difficulty with the huge kelp farms envisioned by Dr. Wilcox was the enormous capital cost of the system.  In order to produce energy at competitive costs, the proposed farms would have to be extremely large, 100,000 acres or more.  This need for excessive start-up capital results mostly from the tendency of the upwelled nutrients to promptly “leak” away around the edges of small farms.  Eventually, the U.S. Navy documented the research and field experiments in multiple volumes,2,3 and abandoned the project in the late 1970s.

After many years of pondering these problems, Brian Howard Wilcox (son of the late Dr. Wilcox), co-founder of Marine BioEnergy, Inc., filed a patent in 2008 on a new approach – to use low-cost underwater drones to tow farms of kelp in the open ocean, diving to depths to absorb nutrients and surfacing to absorb sunlight.  Brian has 35 years of experience designing and building robots for extreme environments for NASA, DARPA, and others.