This paper describes the results of a calculation of the exergy flows in term of the circulation of matter obtained from composting garbage in an urban area. The purpose of using the concept of exergy is to show explicitly the relation between the rate of the production of renewable resources such as vegetable and compost and the rate of the consumption of non-renewable resources for the transportation of garbage and the operation of a composting plant. It is found that the amount of exergy consumed for operating a composting plant is twelve times that of exergy contained by the vegetable produced using the compost. The amount of exergy consumed for the delivery of the garbage and the compost is one-fourth of the exergy contained by the vegetable.