One of the many advantages perpetually claimed for the external combustion Stirling engine over it's internal combustion (IC) contemporaries is that it produces lower exhaust pollutants. However, this claim was made before carbon dioxide (CO2) was identified as one of the most important contributors to the undesirable greenhouse effect. Unfortunately, the more efficient combustion of a Stirling system results in proportionately more CO2 being produced than with an equivalent IC engine. Therefore, if the Stirling is to maintain it's position as an environmentally friendly engine, then some efficient means of removing the exhaust CO2 must be found. Of the many techniques available for removing this gas, the cryo-process appears to be well suited for use with the Stirling. However, a rudimentary analysis, presented in this paper, of such a system has indicated that the performance penalties imposed by making provision for CO2 removal would probably be unacceptable.