6.5.3 Supply curves of conserved carbon dioxide
CO2 conservation supply curves relate the quantity of CO2 emissions that can be reduced by certain technological or other measures to the cost per unit CO2 savings (Sathaye and Meyers, 1995). The measures, or packages of measures, are considered in order of growing marginal CO2 abatement cost, therefore forming a ‘supply curve’ for the commodity of CO2 reduction.
Figure 6.4 depicts the potentials for CO2 abatement as a function of costs for eight selected recent detailed studies from different world regions. The steepness of the curves, that is the rate at which the costs of the measures increase as more of the potential is captured, varies substantially by country and by study. While the shape of each supply curve is profoundly influenced by the underlying assumptions and methods used in the study, the figure attests that opportunities for cost-effective and low-cost CO2 mitigation in buildings are abundant in each world region. All eight studies covered here identified measures at negative costs. The supply curves of developing countries and economies in transition are characterized by a flat slope and lie, in general, lower than the curves of developed countries. The flat slope justifies the general perception (for instance, which provided the main rationale for the Kyoto Flexibility Mechanisms) that there is a higher abundance of ‘low-hanging fruit’ in these countries. More concretely, the net costs of GHG mitigation in buildings in these countries do not grow rapidly even over 30–50% of emissions reductions. For developed countries, the baseline scenario assumes that many of the low-cost opportunities are already captured due to progressive policies in place or in the pipeline.