What Is a Green Bond?

A green bond is a fixed-income debt instrument that works exactly like a conventional bond in terms of repayment obligations, except that the issuer commits to spending the money it raises exclusively on projects with a defined environmental benefit — renewable energy, energy efficiency, clean transportation, sustainable water management, and similar categories.

How it works mechanically

A green bond has the same basic anatomy as any other bond: a face value, a coupon rate, a maturity date, and a credit rating tied to the issuer’s ability to repay. An investor buying a green bond is still primarily assessing the issuer’s creditworthiness, not the environmental project itself — the bond is a claim on the issuer’s general repayment capacity (or, in some structures, on specific project revenue), not equity in the project.

What makes it “green” is a layer on top of that standard structure:

• Use-of-proceeds commitment. The issuer designates the funds raised for a specific pool of eligible green projects, tracked separately from its general funding.
• Project evaluation and selection criteria. The issuer publishes how it decides which projects qualify.
• Management of proceeds. Funds are typically tracked in a sub-account or otherwise formally earmarked until they’re allocated.
• Reporting. The issuer periodically reports on where the money went and, often, the environmental impact achieved — additional disclosure that a conventional bond doesn’t require.

Many issuers align this structure with a recognized voluntary framework, such as the Green Bond Principles, and some seek an external review or second-party opinion confirming the bond meets the framework’s criteria. None of this is legally required in most markets — it’s a market-driven set of conventions that gives investors confidence the “green” label reflects a real, disclosed process rather than just marketing.

Who issues them

Green bonds are issued across the same range of borrowers as conventional debt: national governments (sometimes called sovereign green bonds), municipalities, supranational institutions like development banks, and corporations across sectors well beyond obviously “green” industries — utilities, real estate, manufacturers, and financial institutions all issue them to finance eligible capital projects.

Green bond vs conventional bond

	Conventional bond	Green bond
Repayment obligation	Backed by issuer’s general credit (or specified assets)	Same — repayment isn’t tied to project performance
Use of proceeds	Unrestricted, general corporate purposes	Restricted to designated eligible green projects
Reporting	Standard financial disclosure only	Standard disclosure plus periodic use-of-proceeds and impact reporting
Credit risk	Based on issuer’s overall financial health	Same — the “green” label doesn’t change credit risk
Yield	Set by market conditions and credit rating	Same drivers, sometimes trades at a modest yield premium or discount (“greenium”) to a comparable conventional bond

The credit risk point is worth underscoring: a green bond from a financially weak issuer is not safer than a conventional bond from that same issuer. The environmental commitment governs what the money is used for, not the likelihood of repayment.

The “greenium”

In practice, green bonds from the same issuer sometimes price slightly differently than an otherwise identical conventional bond — commonly at a marginally lower yield, reflecting stronger investor demand from funds and mandates specifically seeking sustainability-labeled debt. This yield difference is informally called a “greenium.” It isn’t universal or guaranteed, and when it does appear it tends to be small — a few basis points rather than a meaningfully different return profile. It reflects demand dynamics in the market at issuance, not a structural feature of the bond itself.

The main risk: greenwashing

Because the “green” label rests on the issuer’s own disclosed criteria and voluntary reporting rather than a single universal legal standard, the central risk for investors is greenwashing — proceeds being allocated to projects with a marginal or contested environmental benefit, or reporting that’s vague enough to obscure what was actually funded. Investors who care about the label’s substance generally look for third-party verification, clear and specific eligible-project categories, and follow-through on reporting commitments in the years after issuance, rather than taking the “green bond” label alone as sufficient.

How it relates to other bond features

A green bond can be combined with other standard bond features — it can be callable (see what a callable bond is), it can carry specific covenants (see what a bond covenant is), and its yield relative to its coupon still follows the same coupon rate vs yield to maturity mechanics as any other fixed-income instrument. The environmental use-of-proceeds designation is layered on top of, not a substitute for, all the usual bond mechanics an investor needs to evaluate.

The takeaway

A green bond is ordinary debt with an added, disclosed commitment: the proceeds fund a defined set of environmentally beneficial projects, tracked and reported separately from the issuer’s general finances. Credit risk and repayment obligations work exactly as they would for a conventional bond from the same issuer — the label changes what the money is used for and what gets reported, not who’s ultimately on the hook for repaying it.