Guarantees of Origin (GO): what they are, how they work and what they are used for
What are Guarantees of Origin (GO)?
Guarantees of Origin (GO) have become a key element in promoting a clean energy model and contributing to transparency in the electricity market. Their use encourages decarbonisation and the use of clean energy while responding to a growing demand for electrification and energy traceability. But what exactly are Guarantees of Origin, how do they work and what are they used for? We take a look at the role of these certificates, who issues them, how they are traded and why they have become a strategic tool for both companies and consumers.
Guarantees of Origin (GO) are electronic certificates that attest that a specific amount of electricity has been generated from renewable energy sources, such as onshore or offshore wind, solar or hydroelectric power. Each certificate generally corresponds to one megawatt-hour of renewable electricity produced and fed into the electricity network. Their main function is to provide traceability and transparency to the electricity system, making it possible to demonstrate the renewable origin of the energy consumed.
Although the electricity flowing through the electricity networks cannot be physically distinguished according to its source, Guarantees of Origin make it possible to prove and document, in a verifiable manner, the link between renewable production and the energy consumption of businesses, public authorities and private individuals.
What are Guarantees of Origin used for and what are their benefits?
As well as promoting transparency, Guarantees of Origin serve to drive and encourage the development of new renewable capacity. By creating a specific market for certificates, they provide an additional financial incentive to clean energy producers and enable energy suppliers and large companies to underpin renewable supply contracts.
They are also a tool used by companies to demonstrate compliance with sustainability targets, emissions reduction targets and climate commitments. Many companies use them to show that some or all their electricity consumption is linked to renewable generation, which is particularly relevant in sustainability strategies and international decarbonisation initiatives.
Some of the main benefits of Guarantees of Origin are:
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Energy transparency
Guarantees of Origin enable the renewable origin of the electricity consumed to be identified and verified. Consumers and businesses can use these certificates to verify that their energy is backed by clean production.
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Promotion of renewable energy
They encourage new investment in renewable technologies by facilitating the issuance of certificates for clean generation.
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Emissions reduction
They help companies and institutions to support climate targets and carbon footprint reduction strategies linked to electricity consumption.
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Compliance with sustainability criteria
Guarantees of Origin enable companies to demonstrate their environmental commitments to investors, customers and regulators as part of their corporate responsibility policies.
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Traceability and market confidence
The system prevents the double counting of certificates and ensures that each unit of renewable energy can only be used once to certify green consumption.
How does the Guarantees of Origin certification system work?
The renewable energy certification system operates through institutions or registration and tracking platforms that certify the production, transfer and cancellation of renewable certificates. Although the model shares common principles across much of the world, there are regulatory and operational differences between regions.
Certification of Guarantees of Origin is specific to the European Union (EU) and European Directive 2018/2001/EC (previously European Directive 2009/28/EC) harmonises it, establishing a common framework for its promotion. The model is particularly well developed in the Nordic EU Member States, where renewable energy penetration is high, and is also fully integrated into systems in countries such as Spain.
In the United Kingdom, following the UK’s withdrawal from the EU, the certification system is based on REGOs (Renewable Energy Guarantees of Origin) as opposed to the European Guarantees of Origin, and these serve a function equivalent to the European Guarantees of Origin, albeit within their own regulatory framework.
Outside Europe, there are similar systems and instruments, but with different structures. In the United States and Canada, RECs (Renewable Energy Certificates) are used; these certify renewable generation and are traded on regional or state-level markets. Regulation is not standardised at federal level, resulting in a more fragmented system than the European one.
There is also an international mechanism known as I-RECs (International Renewable Energy Certificates), designed to facilitate the trading of renewable energy certificates between different countries, particularly in regions where there is no robust national system. This standard provides a consistent approach to certification and broadens access to global green energy markets, and is becoming increasingly common in countries across Asia, Africa and Latin America.
Process of issuance, transfer and redemption
In the Guarantees of Origin system, there are three fundamental concepts relating to different aspects of the model: issuance, transfer and redemption.
Issuance is the point at which the Guarantees of Origin certificate is issued. Renewable energy producers generate electricity and feed it into the electricity network. Based on this verified production, a certificate is issued for every megawatt-hour of renewable origin. These certificates are registered in an official system that ensures their traceability.
Transfer refers to a key feature of the system: Guarantees of Origin can be traded between different players in the energy market. Producers can sell them to energy suppliers, intermediaries or large consumers who need to demonstrate the renewable origin of their electricity consumption. At the European level, these transfers can take place between European Union countries, thanks to the interconnection and interoperability of national systems.
Redemption or cancellation involves assigning the guarantees to an electricity consumer, who is identified by their CUPS (Universal Supply Point Code) or NIF (Tax Identification Number). This is to prove that the energy consumed is renewable. The Guarantee of Origin certificate must be cancelled or redeemed and therefore ceases to exist on the market to prevent its reuse. The aim is to ensure the integrity and reliability of the mechanism.
The life cycle of a Guarantee of Origin (GO) certificate
The Guarantee of Origin certificate system, specific to the European Union, serves to certify that the electricity consumed has been generated from renewable sources. This is how the model works.
The GO cannot be transferred to multiple holders at the same time: there is only one registered owner for each certificate at any given time
Renewable energy generation
A renewable power station generates electricity. The system measures the amount of electricity generated precisely and records each megawatt hour produced in the GO certificate system.
Issuance of the Guarantee of Origin
The national issuing authority or certifying body creates a digital certificate for every MWh generated and verified as renewable. This certificate includes key information such as the type of renewable source, the date of generation and the amount of certified energy.
Obtaining the Guarantee of Origin
The GO is registered in the name of the energy producer in a national register. This producer may transfer the GO independently of the physical energy.
Transfer
GOs can be sold or transferred to energy suppliers or end consumers. Every transaction is recorded to ensure that the same certificate is not used twice. The producer can transfer the GO to a trader, who will then use it or resell it. The producer can transfer the GO directly to an end consumer who wishes to redeem it to demonstrate their use of renewable energy.
Redemption or cancellation
An end consumer wishing to demonstrate renewable consumption requests the redemption of the GO. This step marks the GO as used, preventing its reuse.
Other regions of the world have models and instruments similar to Guarantees of Origin, but they do not always have a centralised and harmonised infrastructure
SEE INFOGRAPHIC: The life cycle of a Guarantee of Origin (GO) certificate [PDF]
The role of regulatory bodies
In the European Union, each Member State has its own issuing body for Guarantees of Origin certificates, coordinated under common standards that enable interoperability between national systems. Organisations such as the Association of Issuing Bodies (AIB) facilitate this coordination and link the European registers.
For example, in Spain the National Markets and Competition Commission (CNMC) manages Guarantees of Origin within the European framework, ensuring their traceability and correct application. In France, Powernext fulfills this role, while in Germany the Federal Environment Agency (Umweltbundesamt) manages the system.
However, the regulatory role varies in other markets. The Office of Gas and Electricity Markets (Ofgem), the UK energy regulator, manages REGOs; RECs operate under a fragmented system with independent regional registries; and no single public regulator oversees I-RECs either, but authorised local bodies in each country manage them in accordance with the international standard.
The future of Guarantees of Origin and consumer demand
The demand for Guarantees of Origin is linked to the drive towards the electrification of the economy and the decarbonisation targets set by businesses and governments. Holding this type of certification provides proof of a connection to renewable energy sources and a consequent commitment to global climate targets and corporate sustainability strategies. This is particularly important at a time when consumer demand is growing: in its Electricity 2026
External link, opens in new window. report, the International Energy Agency estimates that global energy demand will grow by an average of more than 3.5% per year until 2030.
In Europe, Guarantees of Origin have established themselves as the main mechanism for certifying renewable electricity, and all the signs suggest that their importance will continue to grow. The expansion of sectors such as electric vehicles, data centres and industrial electrification, together with the growth in renewable energy power purchase agreements (PPAs), is expected to bring with it the need to provide verifiable proof of renewable consumption. The European Commission itself considers that these systems will be fundamental to building more transparent, integrated energy markets geared towards a cleaner energy model.
One area that will influence the accuracy of energy traceability is the drive towards digitalisation, which may even enable real-time estimates. Technologies such as artificial intelligence can enhance the security of this certification system.
However, the system also faces significant challenges. These include the need to harmonise international standards, avoid an oversupply of certificates that would reduce their value and ensure that Guarantees of Origin genuinely contribute to driving new renewable capacity rather than merely certifying existing production. Even so, the global trend points towards an expansion of these mechanisms, with systems such as I-RECs extending renewable certification to emerging markets and fostering the development of an international green energy market.
Frequently asked questions about GOs
Here are some of the most common questions about certificates that attest to the renewable origin of electricity.
How can I be sure that the energy is 100% renewable?
The way to verify that an electricity supply is 100% renewable is through a certificate such as Guarantees of Origin in the EU, RECs in the US and Canada, or I-RECs in other countries. Energy suppliers purchase and redeem these certificates to back their customers' consumption, thereby certifying that an equivalent amount of renewable electricity has been generated and fed into the electricity network.
Do Guarantees of Origin certificates have an expiration date?
Yes. Guarantees of Origin have a limited validity period to ensure that the renewable backing is linked to recent electricity generation. The general rule stipulates a validity period of 12 months from the date of generation, although some countries extend this period to 18 months. In these cases, the additional six months are solely for the purpose of redeeming the Guarantees of Origin.
Are Guarantees of Origin issued in one EU Member State valid across the EU?
Yes. The European system of Guarantees of Origin is harmonised under EU legislation, which means that certificates issued in one country can be transferred and used in other Member States. This facilitates an integrated European market for renewable electricity and enables companies or suppliers to purchase Guarantees of Origin from different European countries.
Are Guarantees of Origin issued in Europe valid in the rest of the world?
No. European Guarantees of Origin operate primarily within the European regulatory framework and in the countries connected to that system. Outside Europe, there are other equivalent mechanisms, such as RECs in the US and Canada or I-RECs in international markets. Although they all aim to certify renewable energy, there is not always direct mutual recognition between systems, as they are based on different regulations and standards.