Introduction to Fish Oil
The Alaska Energy Authority and EPA sponsored a pilot scale test of fish oil biodiesel with some of the fuel supplied to UAF where the fuel University of Alaska was tested in a diesel genset. The results indicate that fish oil biodiesel can be used for diesel-based generation, but needs to be handled differently from standard diesel. Two of the biggest issues are its comparatively high cloud point temperature (34ºF) when solid waxy particles begin to form within the diesel fuel and plug delivery systems, and its tendency to oxidize more quickly than petroleum based diesel. Using oxidized fish oil biodiesel in a diesel generator can cause a varnish to form on the fuel injectors and damage the engine’s fuel handling system. The demonstration project ended when every engine used in the test failed due to failures in the fuel delivery system. Subsequent work revealed that the conversion of raw fish oil to biodiesel had removed the natural anti-oxidants in the oil, and that treatment with a food grade anti-oxidant could slow the rate at which the fuel degraded, but that fish oil had a strong natural tendency to oxidize and polymerize.
Where Does Fish Oil Come From?
Fish oil is a natural product obtained by rendering fish, and is sold as a dietary supplement, sometimes by prescription for cholesterol control. However, the potential supply of fish oil is currently greater than the market for human consumption, so it can also be used as a fuel, especially in communities with fish processing plants. Worth noting is the relative values of fish oil in its various forms—as a prescription drug, it sells for several thousand dollars a gallon, as a non-prescription dietary supplement it sells for several hundred dollars a gallon, and as a substitute for diesel fuel it is valued at several dollars per gallon.
The oil is rendered from fish waste using a multi-step process of heating, pressing, centrifugal separation, and filtering. Fish oil can be used either directly as a boiler fuel or converted into a biodiesel and used for diesel engine fuel and/or heating fuel. Raw fish oil is also being used by a number of fish processors around the state for onsite heating and power generation.
Fish Oil in Alaska
Despite these challenges, fish oil and fish oil biodiesel can be an economical alternative in communities where large quantities of fish oil is readily available. The recent rise in the cost of diesel fuel has created greater incentive to render fish oil to replace conventional diesel in rural Alaska. Alaska currently produces roughly 8 million gallons of fish oil each year. The majority of this oil is produced by the largest fish processors in the Aleutian Islands.
Challenges of Fish Oil
Statewide, there is an estimated 13 million gallons of unrecovered fish oil each year from the fish waste of Alaska’s many small fish processors. Individually, these processors do not have the throughput to justify the capital cost of fish oil rendering equipment. A portable fish oil rendering facility might provide a solution to this problem. For the past several years, the Alaska Energy Authority has tried to encourage the development of such a module, but unfortunately its efforts have met with little success. Long distances between processing sites and short, overlapping fishing seasons are significant hurdles that hurt the economics of a portable fish oil rendering module.
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