A diesel engine running in dual fuel mode with diesel as pilot fuel and producer gas as primary fuel produces 3.5 kW at rated engine speed and is coupled directly to a generator for producing electricity. The amount of diesel and producer gas consumed per hour is 460 ml and 12.5 m3, respectively. Assuming calorific value of diesel and producer gas as 35280 and 3.97 MJ m-3, respectively, the brake thermal efficiency of the engine in percentage is