What Is a Renewable Energy Credit? Uses, Trading, and Retirement

A renewable energy credit, often abbreviated REC, is a tradable certificate representing the environmental attributes of one megawatt-hour of electricity generated from a qualifying renewable source and delivered to the grid.¹ The credit carries the “green” value of that power — the fact that it came from wind, solar, geothermal, or biomass — while the physical electricity flows into the shared grid and is used by whoever happens to draw it. Because those two things are legally separate, a REC can be bought, sold, and retired on its own, and that separation is what makes it possible for a business in a coal-heavy region to credibly claim it runs on renewable energy.

What a REC Actually Represents

A REC is a market-based instrument that conveys the property rights to the environmental and other non-power attributes of renewable electricity generation. One credit equals one megawatt-hour. The credit does not include the electrons themselves; it includes only the environmental value of having produced that megawatt-hour from a clean source.¹

Because the credit is distinct from the power, it functions as intangible personal property. The generator initially owns both the electricity and the credit. Once the power enters the grid, the generator can sell each one to a different buyer under different contracts. That is why RECs exist as a category at all: the grid mixes electrons from every source, so there is no way to physically deliver “solar electricity” to a specific customer. The credit is the accounting mechanism that assigns the renewable claim to one buyer and only one buyer.

What Information Each Credit Carries

Every REC carries identifying data that stays attached to it from creation through retirement. According to the EPA, that includes:

Renewable fuel type, such as solar photovoltaic, wind, or biomass
Facility location
Nameplate capacity of the project
Project vintage — the date the facility began commercial operation
Certificate vintage — the month and year the electricity was generated
A unique identification number that prevents any megawatt-hour from being counted twice
The tracking system ID showing which registry issued the credit
The utility to which the project is interconnected
Whether the credit qualifies for a particular state’s renewable portfolio standard

This record lets regulators, buyers, and auditors verify exactly where, when, and how the renewable electricity was produced.¹ The unique identification number matters most: it is what stops the same megawatt-hour from being assigned to two different credits.

Bundled and Unbundled Credits

RECs come in two forms. A bundled REC is sold together with the underlying electricity, typically through a power purchase agreement between a generator and a buyer. An unbundled REC has been separated from the physical electricity, so the environmental attributes are sold as a standalone product to a different buyer.²

In regulated electricity markets, the local utility is often the only permitted buyer of the physical power. The generator can sell the electricity to the utility under one contract and sell the RECs separately to a corporate buyer or REC marketer under a different one. In competitive markets, the generator has more flexibility and can sell both together or split them. Projects in all states can sell unbundled RECs as a standalone product regardless of market structure.²

Who Buys RECs and Why

State Compliance Markets

The largest source of demand comes from state Renewable Portfolio Standards. An RPS requires electric utilities and other retail electricity providers to supply a minimum percentage of customer demand with eligible renewable resources.³ Roughly 30 states, Washington D.C., and two U.S. territories currently have mandatory renewable or clean energy requirements, and a handful more have set voluntary goals.

Utilities prove they have met their obligations by submitting RECs to state regulators. If a utility falls short, most states impose an Alternative Compliance Payment — a per-megawatt-hour financial penalty that varies by jurisdiction. Those penalties create a price ceiling of sorts for RECs in compliance markets, because utilities will generally pay for credits whenever the market price sits below the penalty. Targets, eligible technologies, and penalty amounts differ by state, so a credit that qualifies under one RPS may not count toward another’s.

Voluntary Buyers and FTC Rules

Outside government mandates, corporations, institutions, and individuals buy RECs voluntarily to meet their own sustainability targets. Voluntary buyers face no government penalty for skipping a purchase. They do, however, face the Federal Trade Commission’s rules on environmental marketing when they make public claims.

The FTC’s Green Guides, codified at 16 CFR Part 260, include a section on renewable energy claims. Under those rules, it is deceptive to claim a product is “made with renewable energy” unless all, or virtually all, of the significant manufacturing processes are powered by renewable energy or matched with RECs. A company that generates its own renewable electricity but sells the RECs to someone else cannot also claim to use renewable energy itself.⁴ The guides also recommend specifying the source, such as wind or solar, to reduce the risk of misleading consumers.⁵

How Credits Are Issued, Traded, and Retired

RECs are created, transferred, and retired inside electronic registries run by regional tracking organizations. Nine primary tracking systems currently cover all U.S. states, including WREGIS in the west, PJM-GATS in the mid-Atlantic and parts of the Midwest, M-RETS in the Midwest, NEPOOL-GIS in New England, and NAR across several additional states.⁶

Before a registry issues a credit, the generating facility provides verified output data from revenue-quality meters that measure electricity flowing into the grid. The tracking system audits that information against historical production before minting the digital certificate. Once validated, the registry creates the electronic record that is the REC.

After issuance, the generator can transfer the credit from its registry account to a buyer’s account within the same tracking system. Both parties confirm the transaction, and the ownership records update. Large-volume traders often use standardized agreements that include warranties against title defects and double counting.

The final step is retirement. When a utility needs to prove RPS compliance, or a corporation wants to back a public claim, it retires the credit. Retirement permanently removes the REC from circulation so it can never be sold or transferred again. The EPA advises buyers to make sure their RECs are retired in their name, or retired on their behalf by a supplier, to prevent two parties from claiming the same megawatt-hour.⁷

Vintage and Useful Life

Each credit carries a vintage: the month and year the underlying electricity was generated. Many state RPS programs require the vintage to fall within a specific window, often within a few years of the compliance period. For voluntary programs like RE100, credits generally must come from the same calendar year as the consumption they are meant to match. RECs do not expire the way perishable goods do, but older credits can lose eligibility for particular programs, which effectively limits how long they are useful.

RECs Versus Carbon Offsets

People often mix up RECs and carbon offsets, and the difference matters legally. A REC is measured in megawatt-hours and represents the use of renewable electricity. A carbon offset is measured in metric tons of CO₂ equivalent and represents a reduction in greenhouse gas emissions.⁸

Buying a REC lets you claim you used renewable electricity from a low- or zero-emissions source, which lowers your market-based scope 2 emissions from purchased electricity. Buying a carbon offset lets you claim you reduced or avoided greenhouse gas emissions somewhere outside your own operations. RECs do not require an “additionality” test, meaning proof that the project would not have been built without your purchase. Offsets do.⁸ Buyers of RECs should not make greenhouse gas emission reduction claims based solely on retiring credits; the two instruments answer different questions.

How To Buy a REC

There are several ways to acquire RECs, depending on your local electricity market and how much you need:

Utility green pricing programs. Many utilities offer a green tariff that lets you pay a small premium on your electricity bill in exchange for RECs sourced from renewable projects. This is usually the simplest option for a residential customer.
Community choice aggregation. Some local governments aggregate demand within their jurisdiction and negotiate bulk renewable contracts for participating customers.
Direct purchase agreements. Larger buyers can contract directly with a renewable generator through a physical or virtual power purchase agreement tied to a specific project’s output.
Unbundled REC purchases. Any buyer can purchase credits as a standalone product from a REC marketer or broker, separate from their electricity service, in any state.

Whichever route you take, confirm the RECs will be retired in your name inside a recognized tracking system. That is the only way to make sure the environmental claim is legally yours and that no one else can use the same credit.⁷

1
US EPA. Renewable Energy Certificates (RECs)
2
US EPA. Unbundle Electricity and Renewable Energy Certificates
3
US EPA. Chapter 5: Renewable Portfolio Standards
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eCFR. 16 CFR Part 260 – Guides for the Use of Environmental Marketing Claims
5
FTC. Guides for the Use of Environmental Marketing Claims
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US EPA. Status and Trends Report on U.S. Energy Attribute Tracking Systems
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US EPA. Double Counting
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EPA. Offsets and RECs: What’s the Difference?