Carbon Dioxide, as it is co-produced in only a small way - - relative to some all-natural and un-taxable sources of it's emission, such as the Earth's inexorable processes of planetary volcanism - - by our economically essential use of Coal in the generation of abundant, reliable and affordable electric power, is a valuable raw material resource.
Carbon Dioxide can be reclaimed, either from the environment or from various industrial exhaust gas streams, such as those produced by some plants that process that "clean energy alternative", natural gas, which is often contaminated with a large percentage of CO2 just it exits it's natural reservoirs, to make the long-distance shipment and subsequent combustion of that natural gas more efficient. Such extracted Carbon Dioxide from natural gas, as far as we know, is now most often just simply vented to the atmosphere, and is in addition to that generated by natural gas when it is combusted.