Combined Generation of Electricity and Power in the Dairy Industry

Summary

The study into the application of Total Energy systems in the dairy industry is restricted to medium size units (about 500 kw) and to the sector of powder manufacture. The power and heat demand of this process is analyzed. This leads to TE systems with a low heat/power ratio. Gas engines or diesel engines fit this demand. The study is concerned with an existing skim milk powder plant. The power demand ranges from 425 till 700 kW depending whether the power demand for the handling of the liquid milk is included. The heat should be utilized in the preheating of the drying air, but other ways of energy recovery may be competitive. Diesel engines are less expensive than gas engines, but the heat utilization is slightly lower. The choice will mainly depend on price and availability of the fuel.

In the case studied it appeared attractive to choose for only one engine, and to pay for stand-by power from the public power supply. The charge made for this stand-by power varies strongly from district to district.

The energy savings are substantial; because of the rather high investments the pay back time amounts still about 6 years. When fuel prices increase the savings will increase too, but not at so rapid a pace when the central power stations will use cheaper fuel in the future.