Other key constraints considered in the model were as follows: the upper limit on the ramp up rate for new production technologies, which was set at four plants or a 30% increase in capacity per year to prevent unrealistic explosive growth of a new production technology; the prohibition of new plants with initial technologies after 2025 in order to drive GHG reduction while respecting any existing commitments; and the prohibition of new fossil-based plants in NFAX after 2030 in order to accelerate GHG reduction in this supply scenario. No upper limit was placed on the CCS in the ME or NFAX supply scenarios, assuming the potential export of CO2.