Organic Rankine Cycle Working Fluid Considerations for Waste Heat to Power Applications

This paper describes the results of an analysis of the opportunity for industrial waste heat to power in the United States using the organic Rankine cycle. The EPA National Emissions Inventory databases are used to quantify the available heat content and temperature of the sources. By frequency, the majority of waste heat sources are at temperatures below 450 degrees F (232 degrees C) however, more than half of the total opportunity for waste heat to power comes from sources with exhaust gas temperature between 500 degrees F and 1000 degrees F (260 and 538 degrees C). While these temperatures are not high enough to make steam based generation attractive they are high enough that working fluid decomposition must be considered in the opportunity analysis. For sources under 1000 degrees F (538 degrees C) including the limitations of working fluid decomposition brings the technically recoverable power from 44 to 32 GW. Total opportunity, including all sources over 300 degrees F (149 degrees C) is estimated to be 51 GW In addition to opportunity analysis the kinetics of working fluid decomposition are discussed and calculated for several widely used fluids as a function of temperature.