How much CO2 emissions do we reduce by saving electricity? A focus on methods

In this paper we evaluate two approaches for estimating CO₂ emission reduction from electricity savings: one based on average CO₂ intensities of electricity generation and another that relies on marginal CO₂ intensities. It is found that the average CO₂ intensity approach has a significant shortcoming when it comes to scenario-based approaches for CO₂ emission reduction. This shortcoming lies in the chicken-egg problem created, where larger future electricity savings are actually big enough to change the CO₂ intensity in such a way that it cannot be used anymore to estimate the CO₂ emission reduction. We show that in these cases the marginal approach is preferred. To correctly apply this approach, it is important to determine the CO₂ intensity of the future power mix which will not be built in order to avoid under or overestimation of the CO₂ savings calculated. We propose a seven-step approach which can be used in scenario-based potential studies as guidance for estimating the CO₂ 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 CO₂ reduction potential with the underlying reference scenario. © 2013 Elsevier Ltd.