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Issue link: https://insideunmanned.epubxp.com/i/643419
48 unmanned systems inside January/February 2016 MARINE AQUACULTURE-MARICULTURE "A fish is going to eat 1 to 3 percent of his body weight a day, and they feed seven days a week, 365 days a year," Kelly said. "So if you start to think of the scale of feeding involved with a top-of-the-line, industry-level farm, take a 20,000 square meter (containment) pod, which is pretty standard in the salmon industry, stock it with 20 kilograms per me- ter of fish; have it eat 1 percent of its weight a day—and you're looking at four metric tons of feed per day for that pen. You start to multiply that out by a week and now you're to 28 to 30 metric tons of feed that that pen is going to consume each week." The feeders are automated and deliver the food to the fish through a tube, Lanzetta said. "We will be utilizing a robotic device called an automated feed-buoy," she said, "that was developed by NOAA (the National Oceanic and Atmospheric Administration) and the Univer- sity of New Hampshire. It holds 20 tons of feed and it will feed four pods—it's big." Cleaning the pens is also a huge job. Both Kelly and Lanzetta would like to find the equiv- alent of an underwater Roomba—a robotic sys- tem that would, without a lot of human interac- tion, keep enclosure walls clean. "You are putting stuff into the primordial soup of life," explained Kelly. "Mother Nature sees it, likes to grow things on it." Biofouling causes increased drag on the equip- ment. It also reduces the water flow through the cage and therefore the amount of dissolved oxy- gen reaching the fish—causing stress. "We have to clean the exterior of the pods," Lanzetta said. "It's very important that it be kept clean. Something that might attach and go around the outside of the pod and clean off what grows there. That could be very interest- ing to me." Unfortunately, Kelly said, the capabilities of the systems available today are limited. "Coming from an autonomous vehicle- technology snob perspective, it sort of looks 1950s to me," Kelly said, "but it works and it may make money, so it is what it is." The problem is the current generation of pen cleaning equipment is a "brute force" solution that is clunky, difficulty to use and heavily op- erator dependent, Kelly said. Riptide Autonomous Solutions and Open Water Power have partnered to create a new unmanned underwater vehicle with a 1,000-mile range and a more budget-friendly price tag. Priced at about $10,000 Riptide's Micro-UUV comes in lengths ranging from 25 to 72 inches. Using regular alkaline batteries it can operate for roughly 30 hours and, at 2 knots, traverse some 60 miles. With the new Open Water Power battery, the vehicle's range jumps to 1,000 miles with an operational time of 400 hours. The battery, to be available later this year, uses machinable aluminum and water to create energy, said Jeff Smith, Riptide's president and CEO. Open Water found a way to make the aluminum mildly reactive, he said, then matched it with a specifcally tuned electrolyte. The result is a battery with a very high energy density that is very safe—as has been demonstrated in tests at some of the naval labs, Smith said. "They've put these things in fres. This aluminum, it doesn't burn, doesn't react up to reasonably high temperatures." New battery gives underwater vehicle 1,000-mile range An automated feed-buoy developed by the National Oceanic and Atmospheric Administration and the University of New Hampshire. Photos courtesy of Riptide Autonomous Solutions and the University of New Hampshire