Power and process heat uses in the Citrus Processing Industry provide a good opportunity for achieving fuel savings by means of cogeneration. This paper considers cogeneration possibilities using a diesel engine. Following a review of available engine types, a representative diesel cogeneration system configuration is established based on a 4150-kW medium-speed diesel engine burning residual oil. Heat recovery is described from the engine exhaust gas, the charge air cooler, and the cylinder cooler. At full engine load, the fuel savings associated with this recovered heat are equivalent to about 22 × 106 Btu/hr. The resulting cogeneration heat rate is 3990 Btu/kWh, compared to a typical electric utility heat rate of 10,000 Btu/kWh. Economic analysis indicates that the first year pre-tax simple payback for the overall cogeneration system is approximately 5 years. Paper published with permission.