Electricity disclosure was mandated by the European Commission in the revised Electricity Market Directive (2009/72/EC). The directive states that all electricity suppliers must disclose to their customers the contribution of different energy sources to the portfolio of the supplier in the preceding year. Additionally, they have to disclose related environmental impact indicators, such as CO2 emissions. The goal of electricity disclosure is to provide consumers with information about their electricity consumption and to allow for informed consumer choice.
As the electricity markets are liberalised and electricity can be traded between nations, an instrument is needed to track the required attributes of electricity. Guarantees of Origin (GOs) are such a tracking instrument. For disclosure of the electricity mix, suppliers can use GOs to account for the share of electricity from renewable energy sources they sell. Furthermore, they can also use the so-called residual mix to account for the rest of the electricity that is not tracked with the help of GOs.
The implementation of the directive into national legislation can vary from country to country. Hence, in some countries suppliers can also use other reliable tracking systems than GOs. A typical example would be allocation mechanisms for electricity that was supported under a feed-in support scheme.
Read more about electricity disclosure at the RE-DISS.