Allocating carbon dioxide emissions from cogeneration systems: descriptions of selected output-based methods

Many companies, government agencies and researchers have struggled with the question of how to allocate emissions for cogeneration systems. Some work has been performed, but the results obtained thus far, are not universally accepted, and are often inconsistent, overly complex and difficult to use, and are not based on sound reasoning. In this article, selected methods for allocating emissions for cogeneration systems are described and compared. In addition, exergy values for typical commodities encountered in cogeneration are presented. The reasoning behind this author's view is that the exergy-based method is the most meaningful and accurate of the methods.