In accordance with the Electricity Market Directive 1, all suppliers of electricity are required to disclose their electricity portfolio with regard to energy source and environmental impact, specifying the emissions of CO2 and the production of radioactive waste. The aim of these requirements for electricity disclosure is to provide consumers with relevant information about power generation and to allow for informed consumer choice, which would not only be based on electricity prices.
The Renewable Energy Directive 2 defines a guarantee of origin as a means of proving the origin of electricity. In the case where electricity delivery is not based on a Guarantee of Origin the disclosure to customers should be based on a residual mix of electricity. The residual mix is calculated so that the renewable attributes covered by guarantees of origin which have been cancelled in the region or in a third country have been removed.