The production technologies for the seven basic chemicals with a technology readiness level (TRL) above six were considered in the model (see Table for the technologies considered). They were categorized into three types: an initial technology, which was today's unabated production technology; an end-state technology, which was a fully abated production technology; and a transition technology, which only partially reduced emissions and required an upgrade to an end-state technology in a later year but was needed when end-state technologies were unavailable yet.