Exergoeconomic methods provide an effective approach for identifying,
evaluating and reducing thermodynamic inefficiencies and costs in an energy
system. The aim of this paper is to show the potential for cost reduction on
the demand side, using the exergoeconomic method in the example of real
processes for coffee roasting. More than 6.5•109 kg of coffee beans is
roasted worldwide annually, mostly in batch roasters. Near the end of the
roast, roasting coffee emits volatile organic compounds, carbon monoxide and
other pollutants, which in many industrialized countries have to be oxidized
in afterburners. Afterburners release exhaust gases with a temperature of
250-450°C, depending on the roasting process and the method of exhaust gas
cleaning. The aim of this paper is to use exergy analysis and exergoeconomic
performance evaluation to determine the energy use for coffee roasting and
the afterburning process, and evaluate the way to utilize waste heat and
reduce costs in the factory. For roasters with the capacity of up to 4 tons
of green coffee beans per hour, the potential of heat recovery is 1.1 MW and
the possibility to save money is around 60,000 € per year. This case study is
similar to many others worldwide, and the results of this analysis could lead
to more general conclusions