Integrated renewable energy solutions for seafood processing stations

Abstract

The ENERFISH project aims to demonstrate a new poly-generation application with renewable energy sources for the fishery industry. The distributed energy system utilizes cleaning waste of a fish processing plant to produce biodiesel. The biodiesel is used to produce the locally needed cooling/freezing and heating energy. In addition, a power surplus is generated for the electricity network or local industrial use. The research contribution focuses on optimisation, simulation, validation and planning of piloted concepts. A energy integration auditing and optimisation tools are being developed to carry out feasibility studies for the fishery industry. The advanced CO2 based freezing/cooling system requires optimization and control system planning of special high-pressure equipments. The final biodiesel will be tested in appropriate engines. With a view to marketing possibilities the demonstration will take place in Vietnam. In the demonstration case, the main product of the fish processing plant is catfish filet (about 40 t/d). The fat content of 22 per cent in the fish cleaning waste results in a production of biodiesel of about 13 t/d. A part of the biodiesel is used to produce electricity for the locally needed cooling/freezing (0.3 MW) and heating (1,3 MW) energy. In addition, a power surplus (0,8 MW) is generated for the local industrial use. Fish farming and processing plants in Vietnam produce frozen fish fillet with capacity from some tonnes per day to dozens tonnes/day. One third of fresh fish is yielded as fillet and the rest of fish is treated as fish cleaning wastes. There are some alternatives for utilisation of fish cleaning wastes, one of them is biodiesel and energy production at the own factory. The energy demand at the fish processing factory is dominated by cooling and freezing facilities. 80 % of electricity consumed at the factory is supplied for cooling/freezing compressors, and the cold energy of low temperatures is needed in freezing and cold storage facilities of fillet. Cooling energy of about zero degrees is needed for space cooling of production halls. The specific electricity consumption is about 400 kWh per tonne fresh fish, or 1400 kWh per tonne fish fillet. The electricity load is typically very steady over a day and a year in the Vietnamese conditions. From the energy viewpoint the fish processing plant is energy self-sufficient, when the fish waste oil is processed in a biodiesel processor and further converted to electricity. In addition to this, a part of biodiesel can be sold to the fuel market. The fish processing factory producing fish fillet of 40 ton/day consumes electricity average at a power of 2 MW. 11 ton/day biodiesel is needed for that power production and a surplus biodiesel of 2 ton/day is available for fuel market. At the same time, diesel engine plant generates heat energy at a capacity of 2,6 MW, which is also available. The other end in possibilities of poly-generation is to generate all biodiesel, 13 ton/day, to the fuel market. In Vietnam, electricity and diesel fuel prices are very low being for electricity average 42,6 €/MWh for industry customers, and diesel fuel costs 400 €/ton. This results in shutdown of private electricity production (except during electricity blackout), even if cogeneration heat could be utilized. And the markets for biodiesel should be found outside Vietnam. According to the calculations and assumptions presented in this report, biodiesel production from fish cleaning wastes is profitable, and the payback period of the investment seems to be very short. However, more information on the technical and economical performances related to the operation and equipments are needed.