Guarantees of origin
A guarantee of origin (GO) provides proof that a renewable electricity generator is actually producing renewable energy and injecting it into the public grid.
To provide irrefutible evidence of the origin and quality of the electricity, the GO — which is issed by the system operator free of charge — must include the following information:
energy source from which the energy was produced and the start and end dates of production;
wheter it relates to electricity or heating or cooling;
the identity, location, type and capacity of the installation where the energy was produced;
whether and to what extend the instatalltion has benefited from support and the type of support;
the date on which the installation became operational;
he date and country of issue and a unique identification number.
The system operator normally issues the guarantees of origin using E-Control's GO database, where the amount of renewable electricity generated by the plant is recorded. OeMAG registers the supported renewable electricity bought by it in the E-Control database itself.
Renewable electricity can only be sold as such if a guarantee of origin is transferred to the buyer. Under the labelling system, the GO is cancelled as soon as the electricity is delivered to the consumer (see section 8 
[Green Electricity Act] and section 79
Elektrizitätswirtschafts- und -organisationsgesetz
With redeeming the GO for labelling, the GO's life cycle comes to an end at the consumer's, who can choose a supplier not only on the basis of economic but also ecological criteria.
If proof of origin cannot be provided for a certain quantity of power, this is referred to as "electricity of unknown origin – ENTSO-E mix". The ENTSO-E mix is the average energy mix of the transmission network operators associated in the ENTSO-E (European Network of Transmission System Operators for Electricity). In 2009, the ENTSO-E mix was made up of 12,58 hydropower, 51,41 fossil fuels, 28,89 % nuclear energy, 6.74 % other renewable energy and 0.39 % other energy sources.