Public information

Having worked since 2001 to improve and simplify the system of tracked energy, RECS Energy Certificate Association (formerly RECS ) has unmatched expertise in the issuance, trade, and cancellation of renewable energy certificates – the process that allows consumers to claim the use of a specific volume and type of renewable energy.  

You will find more information below about EAC systems, standards for EAC markets, and the role of RECS . RECS members have access to more detailed information on a wider range of topics on the member’s information page.

Understanding EAC markets

Energy attribute certificates (EACs) have been around since the late 1990s. More than 20 years later, the market for EACs has developed significantly. While these markets were initiated in Europe and the US, in many countries around the world EAC markets are now emerging and evolving. Regulation and procedures may differ between these EAC systems, but at their core these systems have one common function, to trace the attributes of a given megawatt-hour of electricity from a producer to a consumer.

By reading further you can learn about the history of these markets, their basic components and principles and the various concepts associated with them, such as full disclosure and dual reporting. To understand more about EAC markets in other countries, click here.

The basics of EAC markets

EAC markets were created because electricity cannot be tracked between producer and consumer as other products, such as Fairtrade coffee, can. Electricity is not a tangible product that can be physically transported. It is a charge that must be maintained on a grid. Even if you buy your power from a specific producer they cannot box and deliver this power directly to you. Instead, they inject their electrical charge onto the grid in one place and somewhere else you take the same amount of charge off the grid. System operators work to maintain a balance between the injection and off-taking of power. Without this balance, the grid will fail and cause blackouts. When we buy power, we are not buying physical electricity, we are buying the right to remove a given amount of charge from the grid. Therefore, the only way to track the production and use of a megawatt-hour of power, along with its attributes, is through a book & claim accounting system, which lets EAC market participants book the attribute certificates when power is injected into the grid, transfer those attributes to their consumer, who then claims them as proof that they paid for a given type of electricity.

At its most basic level, the EAC system works as follows:

  1. a producer of (renewable) electricity generates 1 unit of electricity (generally this is 1 megawatt-hour (MWh))
  2. for each MWh of power they inject into the grid the producer requests an EAC from the issuer; the EAC, which is an electronic certificate, contains factual information attributes about the specific unit of electricity such as the technology used to generate the power and where it is located.
  3. the EAC can be traded between market participants through registries with the ultimate aim of selling it to a consumer (also known as an end-user).
  4. The end-user or their representative consumes the EAC by cancelling it so that it cannot be used again – without cancellation, there is a risk that one EAC can be used twice (known as double counting)
  5. the consumer can then claim to have consumed the unit of power that was represented by the EAC.

The EAC market is separate to the electricity market. Even though each EAC is associated with a specific unit of electricity, EAC markets are not about allocating the electricity but are about allocating its attributes. Most often these are “renewable attributes” so that the electricity consumer can claim the consumption of renewable power.

Energy attribute certificate systems prevent the double sale or consumption of the attributes of a particular unit of electricity. All consumption of energy attributes should have the associated EAC cancelled, as there are no other means to ensure the prevention of double issuance or claiming. This applies to all electricity contracts including power purchase agreements (PPAs).


An EAC, such as the guarantee of origin (GO) in Europe, is a unique electronic certificate, which is issued for a single MWh of electricity produced. The certificate is generated within an electronic registry and consequently traded via the owners of these registry accounts. At the end of its life cycle, the EAC must be cancelled by a consumer or their representative (such as a power supplier), so that it cannot be used (and disclosed or claimed by another consumer).

EAC registries are created and maintained by different companies, such as Grexel in Europe, Unicorn in the US and I-REC Services globally. In Europe, each EU Member State and EEA country has their own issuing body and registry operator.

It is important that the different registries are compatible, so that market participants can easily trade EACs between countries. The Association of Issuing Bodies (AIB) has created a “hub”, a central data space via which trades can take place between compatible national registries. The AIB also created a standard for issuing, trading and cancelling GOs, the European Energy Certificate System (EECS) Rules.

Trading attributes

Markets evolve where there is a demand. There have been electricity markets since the beginning of the 19th century, but the demand for renewable attributes only came into existence when there was a desire to consume electricity from renewable sources.

Each MWh of produced electricity has its unique characteristics associated with it, such as:

  • time and date of production
  • location of the generation device
  • generation technology (eg. wind turbine, hydropower plant etc.)
  • age of a production device

These characteristics are called attributes, and the EAC market offers a tool for trading these attributes. This list of attributes is potentially endless (for example, should anyone be interested in the colour of the wind turbine they are buying power from this could be an attribute on the EAC). While we commonly speak of purchasing renewable energy, the consumer is actually purchasing renewable attributes. This is understandable given that attributes are an abstract concept to many consumers who are focused on using energy from renewables.

Actors in EAC markets

Renewable attributes trade occurs separately from the electricity market itself. The actors in EAC markets also differ from the actors in electricity markets, because the former operate often in the realm of sustainable and environmental developments, while the latter are only concerned with the electricity itself.


Issuers of EACs are generally independent organizations that facilitate the market and do not participate in the generation, purchase, sale or trade of the EACs. Most issuers in more regulated markets are appointed by the national government to conduct this role and are frequently TSOs, regulators or other natural private parties. In some EAC markets, the issuer will be appointed by a group of local stakeholders or market parties if the government has not appointed the responsible authority. Issuers can broadly be categorized by the standard to which they adhere. The EAC World Map shows a list of issuers, linked to their respective standards.

Market participants

Market participants may broadly be categorized into generators, brokers, traders, suppliers, and consumers. Depending on their mission, which is often influenced by their historical origins, these companies may be only be placed in EACs markets, or they may participate in markets for other products as well, such as electricity or other energy types

The majority of RECS members are market participants of one type or another and collaboration between them and actors on the regulatory side is important to keep EAC markets transparent and well-functioning.


Thanks to EAC systems electricity consumers can choose to buy their power from a renewable source. Consumer choice has always been a major spearhead for RECS and we have seen the role of consumers in accelerating the transition to renewable energy growing and receiving more attention over the years. Some consumers, particularly smaller ones such as households, rely on electricity suppliers to offer ‘green tariffs’ which they deliver on by cancelling GO’s on behalf of their customers. Larger consumers, such as big corporate entities, source power themselves and make deals directly with electricity producers. As a result, renewable energy markets have become more diverse and vibrant.

Household consumers, although often consciously choosing a renewable tariff, are commonly not concerned with, or aware of, the complex matter of EAC systems. They rely on their suppliers to manage the legal side of EAC markets, and they can do so with confidence because the GO is well established in EU law.

For corporate consumers, this is often a different matter. Large multinationals with legal and compliance teams, detailed procurement policies and operations in multiple countries, have to be sure that they are securing agreements that meet their specific needs at a reasonable price. Therefore, they often develop power purchase agreements bi-laterally with electricity producers.

Historical background to EAC developments

The founders of RECS created the first EAC system back in the late 1990s. Although these first “RECS” systems, as they were called, no longer exist, they provided the foundation for what was to become a Europe-wide system for reliably tracking electricity attributes: the Guarantee of Origin system.

Historically, electricity markets in Europe were monopolies and electricity consumers were unable to choose their preferred electricity supplier. With the implementation of the 1996 EU Liberalisation Directive (96/92/EC), electricity markets in Europe were opened up. The idea behind this reform was to increase competition (with the hope of lower prices and better service) and secure supplies. As a result, electricity consumers were able to choose their electricity supplier based on their preferences for service and price.

Renewable energy technologies were still in their infancy in the early 1990s, but the development of environmental policies in the Netherlands created some consumer demand for electricity from renewable sources. Electricity suppliers in the Netherlands, who at that moment still held a monopoly position, were obliged to deliver a given percentage of electricity from renewable sources. A simple book & claim system was created to share the cost of the production evenly over the various suppliers.

This initial book & claim system served as a prototype of the first Renewable Energy Certificate System (RECS). A pilot was conducted between the Netherlands, the United Kingdom, Denmark and Germany. The point of departure was to allow attributes of electricity from renewable sources to be traded across national boundaries. A pan-European system was on the horizon and producers and suppliers across Europe initiated national RECS systems. At this stage, there was little interest from governments or other policymakers engage with the development of RECS systems. As such, these initiatives were led by producers and suppliers together with RECS as their representative.  Together they pushed for the further development of tracking systems in Europe, and for harmonizing these national systems across the continent.

In 2001 the European Union introduced the Guarantee of Origin (GO) in the first Directive on the promotion of the use of energy from renewable sources (2001/77/EC). This system was based on the RECS system and, once it was proposed by the European Commission and agreed by the Council and Parliament, the RECS system was replaced by the GO system. The adoption by the European Institutions of this EAC system was a great achievement and meant that it was now no longer governed by the market but became legally embedded into European Union law.

The GO market has since undergone tremendous development. The Association of Issuing Bodies (AIB) created a standard for the GO system, the European Energy Certificate (EECS) standard, in order to harmonize the various national systems and to offer a central “hub” for the trading of certificates between compliant national systems. While the AIB was concerned with the registry and the process of using the GO (issuance, trade and cancellation), RECS took on the role of representing the users themselves, their position in the markets and their needs from a wider perspective.

Compliance markets and voluntary markets

EACs can be used to measure progress towards national renewable targets, in which case they are part of what are called compliance markets.  These are markets where the cancellation of an EAC is proof of contributing to compliance with the target. Such compliance markets only exist in certain US states, where renewables targets are set in the form of ‘portfolio standards’ under which suppliers have to provide a certain percentage of their power supply to customers as renewable. Even in such compliance markets, consumers can voluntarily choose to buy a greater percentage of their power as renewable than that on offer from their supplier.  When this happens, they create what is known as regulatory surplus – the use of EACs over and above that which is needed to meet the target.

The EU does not use compliance markets with EACs to set renewable energy targets. At European level, targets are set for the amount of renewable energy produced either at a national level (under the 2009 Renewable Energy Directive) or at the EU level (under the 2018 Renewable Energy Directive). Where compliance markets do operate in the EU, such as the Scandinavian El-cert scheme, they are purely created as a support scheme and by purchasing the certificate no claim can be made about the consumption of renewable electricity. Buying GOs (European EAC) is completely voluntary in Europe but must be done in order to claim the usage of renewable electricity for disclosure purposes.

Disclosure can be defined as the public reporting of consumed electricity as verified by a reliable EAC. Generally, RECS recognizes two forms of disclosure, voluntary disclosure and compliance disclosure. Voluntary disclosure is often done by large organizations that report their electricity usage to third-party sustainability standards (such as CDP, RE100, GHGP or others). This is a voluntary form of public information that is not legally mandated but part of an internal expectation regarding their own transparency around their energy use. Generally, it is viewed as a best practice that voluntary disclosures are verified and audited by third parties.

Compliance disclosure, on the other hand, is the requirement to release information about energy use (or fuel-mix (the percentage of a supplier’s power that comes from different generation technologies) if a supplier) to the public and or your clients. Frequently, in Europe, the requirement of compliance disclosure is on the supply company who must report their fuel-mix to their clients as backed by GOs. The disclosure to clients is generally mandated and audited by the national regulator or ‘competent body’. The history of disclosure regulation in Europe is deeply imbedded in EU electricity market rules and is integral to consumer choice in electricity markets.

Dual reporting

Dual reporting means that the production and consumption of electricity are disclosed separately. This is only relevant for Europe because the United States has a market where everything is based on consumption (disclosure and compliance). In Europe, disclosure (the reporting of the electricity people use) is based on consumption but compliance targets (the EU’s targets to increase renewable energy) are based on production.  This, however, is not the full story – as the text of the 2009/28/EC directive on how the gross final consumption shall be calculated explains: “For the purposes of paragraph 1(a), gross final consumption of electricity from renewable energy sources shall be calculated as the quantity of electricity produced in a Member State from renewable energy sources, excluding the production of electricity in pumped storage units from water that has previously been pumped uphill”. Therefore, for legal purposes, the consumption of renewables is based on the calculation of their production.

Dual reporting would give a more accurate view of reality. By counting consumption as well as production it would reflect the choice of renewable energy consumers in national statistics. Moreover, it would require all end-users to report their electricity usage, not only those who currently choose to do so by using GOs. At RECS we believe that if we expect the consumer to play a larger role in the energy transition we must also acknowledge when they are engaging in that transition by buying renewable energy.

The relevance of the residual mix

The true value of purchasing EACs becomes clear when the opposite has no value. In other words, when not purchasing EACs leads to negative consequences, creating an incentive to make a deliberate choice for renewable attributes. EACs provide the instrument for deliberately choosing electricity from renewable sources. Any electricity which is not documented via an EAC tracking system is defined as the residual mix.

As long as not all consumption is tracked using GOs, a residual mix is needed to define the attribute values of electricity which was not documented with a tracking instrument. If the renewable attributes had a certificate attached but were not removed from the mix, then these could be counted by suppliers when disclosing their energy mix, and result in double counting of the attributes. Therefore, only certificates which are not cancelled can be returned to the residual mix.

Most notably this concerns carbon intensity. Where the carbon emissions associated with renewable attributes are zero, the carbon value of non-documented electricity is an average of the carbon emission of all the resources in the residual mix. However, imported and exported attributes need to be taken into consideration and as Europe is an integrated electricity network, the residual mix must be calculated centrally. The AIB publishes the residual mix of Europe on an annual basis: the European Attribute Mix (EAM).

Consequences of a residual mix

Consumers who make a deliberate choice to purchase EACs can claim the use of renewable attributes, but consumers who deliberately choose not to purchase EACs automatically consume the Residual Mix. The more renewable energy attributes are documented and consumed, the more these will be removed from the country’s Residual Mix. As such, the Residual Mix will become “dirtier”, containing more non-renewable attributes, with higher carbon intensities. For companies who need to reduce their environmental impact, using this dirty Residual Mix becomes a risk. Ultimately then, this creates an incentive for companies to deliberately consume renewable electricity, as proven through certificates that detail their attributes.

Standards for trading energy attributes

This chapter could have been termed “EAC systems around the world”, but it is important to realise that in each of the various countries and regions where they operate EAC markets have their own set of rules. At the national level, regulation of EAC markets and systems is intertwined with national laws, usually related to environmental or electricity-related laws. RECS works with members and stakeholders in these national EAC markets and provides expertise to members who seek to become active in these markets. For countries within the European single market, it is important that the rules and regulations which govern their national GO systems are harmonized in order to avoid barriers to trade and to secure a level playing field.

Standards are required for the successful development of EAC markets around the world. The importance of standards is seen clearly in Europe with the development of the Guarantee of Origin system. The creation of the EECS (European Energy Certificate Standard) for GOs allowed for the development of a robust and reliable EAC market in Europe that is now adhered to by most EU Member States, as well as some other EEA/EFTA countries. On an annual basis, we see more than 600-TWh of voluntary trade with 15% growth year-over-year in the use of EECS-GOs in Europe. This robust attribute tracking market is only possible because of the adherence to best practice standards such as EECS. (AR)

Several Experiences in Europe taught us that adherence to a standard for RECs is important for growth and development:

  1. It increases the use of the system by corporate companies (e.g. stimulating external/foreign investment)
  2. Simplifies the choice and trust consumers have when choosing renewable
  3. Eliminates implementation problems when starting a new system, and
  4. Can reduce or even eliminate costs around implementing a REC system.

Other REC standards, beyond the EECS, are the REC Standard and the US REC system which is largely organized by United States laws and consumer regulations.  While many REC markets are large and highly regulated systems all REC markets start their development in a simple step-by-step process. It is a series of very small steps that create a valuable market for renewables producers in the country.

Basic principles for EAC standards

Since the creation of the first EAC system in Europe (see “Historical background to EAC developments”) many EAC systems have been created around the world. Several general principles are crucial in order for these systems to be reliable.

  • No more than one EAC may be issued for each unit (MWh) of produced electricity (Double issuance must be avoided)
  • Jurisdictional areas for issuing bodies should not overlap
  • There can be only one owner of a particular MWh and as such, the attributes of this MWh can only be claimed once
EAC market in Europe and the EECS standard

The GO market in Europe is enshrined in EU law and has been developed through a series of Renewable Energy Directives that came into force in 2001, 2009, and 2018. The new Renewable Energy Directive (2001/2018/EC) includes Article 19 on Guarantees of Origin, which both expands their use in the EU and strengthens the systems that support that use. RECS has developed a detailed analysis of this law, along with guidance for the EU Member States on its implementation at the national level. This guidance follows a number of general principles:

  1. The use of GOs in different EU Member States should be harmonised and standardised. An important step to achieving this will be ensuring that every EU Member State has a nationally mandated body as a full AIB member.
  2. GOs should be issued for all RES electricity production, whether subsidised or not, so that every consumer can know about the power they are using.
  3. In implementing Article 19 of the RED-2, Member States should move beyond basic implementation and towards the development of ‘full disclosure’ systems where every megawatt-hour of electricity production is certified by a GO.

The 2018 Renewable Energy Directive requires Member States to put in place mechanisms for the management of GO systems that are compliant with the European CEN – EN 16325 standard. This standard is a sometimes described as a ‘boiled down’ version of the European Energy Certificate System (EECS) standard that is maintained by the Association of Issuing Bodies (AIB [LINK]) and which must be adhered to by all AIB members. To date, the EECS standard has been adopted by 23 countries[1], who, because they follow common practices, can cross-trade GOs (often referred to as “EECS-GOs”) through a registry which is connected via a central “hub”. The primary role of the AIB is to maintain the EECS code and maintain the functionality of the hub. As a result, companies who want to trade GOs across boundaries benefit from fewer obstacles and less uncertainty.

[1]in 2019, with a few countries awaiting approval

EAC market in the US and the REC standard

Energy attribute certificates in the U.S. are called RECs (Renewable Energy Certificates). As in Europe, a REC is issued for every 1 MWh of electricity produced. US rec markets are governed at the state level and as such the country has a mix of compliance markets and voluntary markets. Most U.S. states have adopted some form of Renewable Portfolio Standard (RPS). Utilities in states with RPS mechanisms are required to comply with rules to sell a specified percentage or amount of renewable electricity to their customers – hence the term compliance markets. Transmission organizations (TSOs/DSOs) or independent system operators (ISOs), which are administered by the Federal Energy Regulatory Commission (FERC), track the generation and retirement of in such compliance markets. RECs in such compliance markets.

Even in compliance markets, aa portion of RECs can be sold on a voluntary basis, outside of the required volumes set out in the RPS schemes. These additional sales are referred to as regulatory surplus. Note that this concept is not relevant in Europe, where consumption of renewables is never subject to targets, and as such cannot be exceeded.

RECs in the voluntary U.S. market are generally sold unbundled from physical electricity delivered to the grid. The U.S. voluntary market is not regulated by TSOs or ISOs, but the Department of Energy and the Environmental Protection Agency (EPA) do encourage the use of tracking systems to regulate generation and retirement and prevent double counting.

REC Standard

The I-REC Standard Foundation is a non-profit organization that provides a robust attribute tracking standard for use around the world. This standard requires local stakeholders and government authorities to facilitate national implementation in adherence with local or national regulations. Based upon the REC Standard and associated Code documents – the blueprints for attribute tracking standards – the Foundation authorizes independent and issuers to implement robust and transparent attribute tracking systems, ensuring the highest quality and adherence to best practices for the avoidance of double counting, double certificate issuance and double attribute claiming. The I-REC Standard ensures that all the RECs issued nationally are done so in adherence with all major international standards including the GHGP, CDP, RE100, ISO and others. More information about the I-REC Standard Foundation can be seen on their website

Non-standardized EAC markets

Non-standardized EAC markets are seen in a few locations around the world from T-RECs in Taiwan to Indian RECs in India. Non-standardized EAC markets are often not as well-regulated as standardised markets. This can make it difficult for stakeholders to fully understand what they are purchasing or compare this to a standardised EAC. Another issue with non-standardized EAC markets is that they often lack a broad understanding of the basic principles of attribute tracking and place requirements on producers or consumers that limit the use or effectiveness of these markets.

The role of consumers in driving renewable energy growth

EAC systems allow for the allocation of renewable attributes from a producer to a consumer. Not only does this provide consumers with an option to choose a specific energy product, but it also puts a level of responsibility on to electricity consumers for the choices they make. Consumers have a choice to purchase renewables or to do nothing. Civil society can, therefore, put pressure on consumers, particularly large corporate consumers to be responsible for their energy use and to participate in the energy transition.

RECS and consumer choice

Historically national electricity markets in Europe were regulated from the top-down, based on monopolized markets where consumers could not choose a specific electricity product. With the liberalization of the electricity markets in Europe, this changed. (See “Historical background to EAC developments”).

Claiming the use of renewable energy

Reliable claims of renewable energy consumption (“renewable claims”) are an important part of the transition to renewable energy economies. Without trust in the claims of renewable energy, the power of consumers to help drive the energy transition will be significantly reduced.

Consumers may make a claim for various reasons, such as brand, complying with internal environmental regulations or for reporting policies.

One example of a consumer claim is: “Our company has consumed 100% renewable electricity this year”

Such claims are not generally regulated by national governments. Before the establishment of attribute tracking standards, such claims could not be verified for reliability and false claims could not be challenged. In response to this problem, standards for good practice in purchasing renewables were established.


It is important not to confuse a ‘Green Label’ with an energy attribute certificate (EAC). An EAC can be applied to energy unit of energy, be it renewable, fossil or nuclear. The EAC only provides information about how, where, and when a given unit of energy was produced.

A green label, on the other hand, can be used to identify a certain quality of EAC, such as one coming from a particular type of energy generation site. For example, when recasting the EU Renewable Energy Directive European legislators instructed the European Commission to: “present a report assessing options to establish an EU-wide green label with a view to promoting the use of renewable energy coming from new installations. Suppliers shall use the information contained in guarantees of origin to prove compliance with the requirements of such a label.”