Comparison of the carbon footprints of combined heat and power (CHP) systems and boiler/grid for supplying process plant steam and electricity

•Grid carbon intensity (Cgrid) has a major impact on carbon footprint comparisons.•There exist Cgrid transition values below which grid provides lowest footprint.•There exist Cgrid transition values above which CHP provides lower footprint.•Fuel type in boiler and CHP affect these transition values.•With Cgrid decreasing globally, CHP and boiler/grid systems may become obsolete.