How much CO_2 emissions do we reduce by saving electricity? A focus on methods

摘要

In this paper we evaluate two approaches for estimating CO_2 emission reduction from electricity savings: one based on average CO_2 intensities of electricity generation and another that relies on marginal CO_2 intensities. It is found that the average CO_2 intensity approach has a significant shortcoming when it comes to scenario-based approaches for CO_2 emission reduction. This shortcoming lies in the chicken-egg problem created, where larger future electricity savings are actually big enough to change the CO_2 intensity in such a way that it cannot be used anymore to estimate the CO_2 emission reduction. We show that in these cases the marginal approach is preferred. To correctly apply this approach, it is important to determine the CO_2 intensity of the future power mix which will not be built in order to avoid under or overestimation of the CO_2 savings calculated. We propose a seven-step approach which can be used in scenario-based potential studies as guidance for estimating the CO_2 emission reductions from not only electricity savings but also renewable electricity and mitigation options that consume electricity such as electric cars and heat pumps. Using our approach would avoid a disconnection of the CO_2 reduction potential with the underlying reference scenario.