Battery manufacturing emits a lot of CO2, to the point that out of the factory, an EV is less green than an ICEV, and it takes about 2 to 3 years of commuting just to catch up. Now with a plug-in hybrid assuming it has half of the battery capacity, it could very well be that the PHEV is actually greener than an BEV. A smaller battery that is enough 90% of the time + an ICE to make up for that 10% could very well be greener than a BEV with twice the battery capacity.