Green bonds and infrastructure: criteria, opportunities and limitations

The first green bond was issued in 2007 by the European Investment Bank. Since then, the market has experienced considerable growth, exceeding one trillion dollars in cumulative issuances in the early 2020s. This growth, driven by institutional investors seeking placements aligned with their climate commitments, has transformed how a growing share of infrastructure is financed.

For a project owner or infrastructure operator, the green bond has become an instrument to consider in the financing structure. It is not always appropriate, it does not replace other instruments, but it offers possibilities worth knowing and evaluating.

The Green Bond Principles, published by ICMA (International Capital Market Association) and regularly updated, structure the market. They define what makes a bond eligible to be qualified as "green" with a minimum of credibility. Several variants have been added since (social bonds, sustainability bonds, sustainability-linked bonds, transition bonds), each responding to a different need.

This article presents the architecture of the Green Bond Principles, eligibility rules for infrastructure projects, impact reporting mechanisms, greenwashing risks and alternatives gaining traction.

The four pillars of the Green Bond Principles

ICMA's Green Bond Principles rest on four components that structure every credible green bond.

First component, Use of Proceeds. Funds raised must be used to finance or refinance eligible green projects, clearly identified in the issuance documentation. Eligible categories include: renewable energy, energy efficiency, pollution prevention and control, sustainable management of natural resources, biodiversity, clean transport, sustainable water management, climate change adaptation, green buildings, circular economy.

Infrastructure projects are well represented in these categories, particularly renewable energy, low-emission transport, energy efficiency in buildings, water management.

Second component, the process for project evaluation and selection. The issuer must describe how it identifies and evaluates eligible projects: eligibility criteria adopted, internal governance process, scope of application, alignment with international standards (Climate Bonds Standards, EU Taxonomy, other taxonomies).

Third component, management of proceeds. Funds raised must be tracked on a dedicated basis, either via a separate bank account or via a robust internal tracking system. The issuer must be able to demonstrate at any time that use of funds remains consistent with the commitment made at issuance.

Fourth component, reporting. The issuer must publish annually (at minimum) a report that details actual use of funds and, ideally, the environmental impacts generated. This reporting is required at least until full allocation of funds, then in case of materiality.

External verification

The Green Bond Principles are not self-sufficient. To secure the credibility of the issuance, quasi-universal practice includes external verification, under one of four forms recognised by ICMA.

The Second Party Opinion (SPO) is the most common option. An independent body examines the issuer's green bond framework, verifies its consistency with the Green Bond Principles and applicable standards, and publishes an opinion before issuance. Recognised actors in this segment are numerous (Sustainalytics, ISS ESG, Moody's, S&P, CICERO, Vigeo Eiris).

Certification (Climate Bonds Certification) is a more demanding approach. It requires alignment with sectoral Climate Bonds Standards, with pre-issuance verification and post-issuance verification by an accredited auditor.

Verification is a form of independent review focused on a specific aspect of the issuance.

Rating is a specific score produced by an ESG rating agency.

For an infrastructure project, the Second Party Opinion is the most widespread form. Its cost is significant but largely offset by the credibility it brings with investors.

Eligible infrastructure projects

Several categories of infrastructure projects are directly eligible for green bond issuances.

Renewable energy projects. Solar farms, onshore and offshore wind farms, hydroelectric plants under certain criteria, geothermal, sustainable biomass. Specific criteria vary according to standards (Climate Bonds Standards, EU Taxonomy, others).

Low-emission transport projects. Railway networks, metro and tram systems, electric buses and their infrastructure, electric vehicle charging infrastructure, rail freight transport. Conventional motorways are not eligible, but dedicated lanes for zero-emission vehicles may be according to recent taxonomies.

Energy efficiency projects. Building energy renovation, high-efficiency cogeneration, optimisation of power grids, smart energy management systems.

Water management projects. Drinking water treatment and distribution, wastewater treatment, efficient irrigation, flood protection and climate adaptation of hydraulic infrastructure.

Green buildings. New construction or renovation meeting recognised certifications (BREEAM Excellent, LEED Platinum, national equivalent).

Climate adaptation projects. Coastal protection infrastructure, reinforcement of structures against climate risks, early warning systems, restoration of ecosystems with protective function.

For each category, the criteria specific to the issuance must be specified in the documentation. An issuer wishing to raise funds for a specific hydroelectric plant will need to demonstrate its alignment with applicable criteria (size, biodiversity impacts, resettlement, methane emissions from tropical reservoirs).

Impact reporting

Impact reporting is the component that distinguishes a credible green bond from a simple labelled issuance. Its quality varies considerably according to issuers.

Robust impact reporting presents several elements.

Detailed allocation of funds. Table of financed projects, with allocated amounts, allocation dates, progress status. Allocation by eligible category is presented.

Impact indicators. By project or by category, the main expected or achieved environmental indicators: MW installed, GWh produced, tonnes of CO2 avoided, kilometres of lines built, m² of certified buildings, m3 of water treated.

Calculation methodology. Assumptions, factors used, comparison frameworks are documented. Reproducibility of calculation is ensured.

Limitations and uncertainties. Areas where calculation is approximate, strong assumptions, alternative scenarios explored, are presented. This transparency strengthens rather than weakens credibility.

Reporting is produced annually, published on the issuer's website, and possibly verified by an external auditor. For investors, it is often impact reporting that determines continuation of the relationship on subsequent issuances.

Greenwashing risks

The green bond market has undergone several episodes of criticism, driven by specialised NGOs or by investors themselves. The main greenwashing risks take five forms.

Undue broadening of eligible categories. An issuer that qualifies as "green" a project that does not meet commonly accepted criteria erodes market confidence.

Excessive retroactivity. Refinancing old projects retrospectively may be legitimate but, if the proportion is too large, it reflects packaging rather than new green investment dynamics.

Absence of DNSH. A project benefiting from a green bond but carrying significant negative impacts on other environmental or social objectives remains problematic.

Insufficient impact reporting. Publishing an allocation without tangible impact indicators leaves the market uncertain about actual environmental materiality.

Absence of corporate transformation. An issuer whose overall activity remains predominantly emitting may be suspected of treating the green bond as a communication tool rather than transition.

Several initiatives aim to limit these drifts: the EU Taxonomy, Climate Bonds certification, strengthened reporting requirements from certain regulators. But investor vigilance remains the first line of defence.

Alternatives: sustainability-linked and transition bonds

The landscape of sustainable bonds has broadened beyond green bonds alone.

Sustainability-linked bonds (SLB) do not finance specific projects but link the financial conditions of the bond to the achievement of performance indicators by the issuer. If objectives are achieved, the coupon remains unchanged or decreases; if they are missed, the coupon increases. This mechanism creates a direct financial incentive for the issuer.

Transition bonds target companies in high-carbon sectors undertaking a credible transition trajectory. They recognise that part of the real economy cannot be classified as "green" today but deserves to be financially supported in its transformation.

Social bonds and sustainability bonds broaden eligible categories to social or mixed social-environmental.

For an infrastructure project owner, the choice between green bond, SLB or other variant depends on the nature of the project and the issuer's strategy. A new renewable energy project naturally leans towards the green bond. A traditional infrastructure company undertaking a transformation may find an SLB or transition bond a better-suited tool.

What investors and DFIs verify.

• Alignment of the green bond framework with ICMA Green Bond Principles.
• Existence of a Second Party Opinion or equivalent, recent and credible.
• Eligibility criteria adopted for targeted categories, their consistency with applicable taxonomies.
• The system for management and tracking of allocated funds.
• Quality of annual reporting, including allocation and impact.
• Absence of DNSH in financed projects.

Green bonds have transformed sustainable infrastructure financing in under fifteen years. They are not a universal solution, but they open up to certain projects broader investor bases, sometimes advantageous conditions, and particular visibility in the market.

Their credibility rests on few rules but they are strict: transparency on use of funds, rigour of impact reporting, independent external verification, alignment with recognised standards. An issuer that respects these rules builds a sustainable reputational asset; an issuer that seeks to circumvent them takes a risk that, in a market becoming increasingly professionalised, is becoming ever more costly.