Guarantees of Origin are electronic documents which provide end consumers with proof that a given amount of power was produced using a certain type of technology. Currently, three variants of these documents are envisaged, certifying the following types of power:

• Electricity produced from renewable energy sources;
• Power for heating and cooling produced from renewable energy sources;
• Electricity produced at cogeneration facilities with an efficient or highly efficient operating regime. 

It is the Guarantees of Origin Issuing Body (EEGO) that is responsible for developing and managing the system used to issue Guarantees of Origin. For more information, send an e-mail to the EEGO at the following address: eego@ren.pt