Abstract: Gaseous carbon compounds can be converted to carbon neutral or negative products using biological processes to metabolise the gaseous carbon compounds or use thermochemical processes to convert gaseous carbon compounds to syngas followed by thermochemical or biological processes to produce products. The gaseous carbon compounds include a mixture of CO2 and CH4 from either a single source, or two or more different sources. Separate biological processes are incorporated to process different gaseous carbon compounds. A gaseous carbon compound produced as a by-product of one biological process can be used as at least part of the feedstock for another process. A renewable energy system can be provided to power equipment. A control system can be used to control flow of gaseous carbon compounds and reactants entering the entire carbon processing systems to provide mass balanced quantities of gaseous carbon compounds and reactants in each processing system and/or between processing systems.