Can Green Bonds Actually Accelerate the Energy Transition?

Investors have been eager to purchase so-called “green bonds” or debt used to finance green projects like renewable energy generation, carbon emissions reduction, carbon capture technology, recycling, electrification, etc.

Unfortunately, this has also led to “greenwashing”, where green financing is not really turning into a useful green initiative in the real world. So despite macro-level research generally associating green bonds with lower emissions and increased renewable-energy deployment, the real impact at a company-level is more dubious.

A new study by researchers at Cardiff University (UK) and Sun Yat-sen University (China) analyzes the impact of green bonds and discusses the future of this important tool in deploying capital in a more sustainable fashion.

It was published in Energy Economics¹, under the title “Green bonds and the energy transition: From instrumental use to intrinsic value”.

Green Bonds Studies

Usage of green bonds has been steadily growing since the European Investment Bank’s inaugural issuance in 2007. By 2024, the cumulative value of green bonds reached $818B, with participation spanning supranational entities and 112 countries.

In parallel, economic studies on the impact of green bonds have followed, with a steep surge in 2019-2020, reflecting heightened scrutiny over the market’s environmental integrity, particularly the risk of “greenwashing”.

Source: Energy Economics

For both academic researchers and finance specialists, the important question is “do green bonds genuinely accelerate the energy transition, or do they merely relabel existing investments?”

The study gathered economic literature published since 2007, with 206 studies ultimately incorporated in this review, with the journal Energy Economics the most used source.

Source: Energy Economics

What We Know About Green Bonds

The research on green bonds can be structured around 3 main themes:

1. Asset pricing of green bonds.
2. Corporate finance of green bonds.
3. Environmental effects of green bonds

Assets Pricing

This research theme focuses on the connectedness between green bonds and other assets, especially oil, natural gas, carbon emission allowances, and clean energy indices.

The findings generally suggest that green bonds offer diversification benefits to equity investors, but their safe-haven feature is weaker than gold.

It also reveals that green bonds receive more volatility (vulnerability to outside shocks) but transmit less volatility to treasury bonds (treasuries are not much affected by green bonds’ volatility).

Maybe more important for investors and fund managers, portfolios with green bonds bring higher risk-adjusted returns than portfolios with conventional bonds in both the US and EU markets.

Lastly, the sample period plays a role in the results of these studies, as studies covering crisis episodes such as COVID-19 or the Russia-Ukraine energy shock tend to find stronger connectedness.

Green bonds and alternative investments have shown strong connectedness. Evidence shows that green bonds exhibit heavy-tail dependence on both cryptocurrencies and artificial intelligence stocks. Overall, green bonds are an effective hedging tool against shocks arising from climate uncertainty, Fintech, and Bitcoin markets.

When it comes to correlation between green bonds and specific assets or asset classes, the result is less clear, with inconsistent results between countries, or on the link between green bonds and oil, gas, carbon credits, or energy ETFs.

The researchers judge that these heterogeneous results stem from different conditions in different geographical markets, and the quick evolution and expansion of the green bonds market over the time period covered.

Corporate Finance Of Green Bonds.

This research theme covers green bond issuance, yields, liquidity, and investor behavior.

Bond issuance is affected by internal factors, like ESG disclosure score, brand reputation, and board structure.

Regarding yields, a long debate in the finance industry and economic science has been whether green bonds enjoy a lower required yield (“greenium”). It seems that greenium estimates differ between certified and self-labeled bonds.

Green bonds are generally more visible and considered for potential investment than standard bonds. Overall, investor behavior around issuance indicates that green bonds enhance corporate visibility and attract an investor base that values transparency, sustainability, and long-term orientation.

Environmental effects of green bonds

While correlation to other financial assets and bonds’ financial characteristics are important for investors, the whole point of green bonds is their potential to have a real-world impact on environmental conditions.

At the macro/country level, studies found positive links between issuance of green bonds and lower CO2 emissions across G10 countries, as well as ecological footprint.

Green bond issuance is associated with increased wind and hydro energy consumption across OECD countries, though the effect on solar energy is not significant, indicating that the effect is not equally spread between renewable energy technologies.

Green bonds can also improve green innovation, including green patents, at least in China.

At the firm level, data are a lot less conclusive, with several authors finding no conclusive effect on CO2 intensity across the US, China, and Russia.

Lastly, green bond policy can shape the effects of green bonds. For example, in China, it has directed them toward innovation, while in Indonesia, they were more toward climate adaptation, and Mexico City municipal green bonds deepened local green finance markets.

An issue with assessing the impact of green bonds is that there is rarely a distinction made between certified and self-labeled bonds, or quality of certification. As such, very real effects of more effective green bonds can be buried in the data when mixed with less reliable ones.

Investors Takeaways

Portfolio Construction

With almost a trillion in value, green bonds are now firmly a part of the global financial landscape, and one likely to keep growing further.

Existing studies indicate that green bonds are a good diversification tool in a portfolio against more speculative assets like cryptocurrencies, AI stocks, and global economic shocks, fulfilling a similar role to traditional bonds.

Importantly, buying green bonds does not mean sacrificing returns, as portfolios integrating them display superior performance.

However, the impact of green bonds on environmental conditions is more mixed, despite being the core reason for their existence in the first place. Green bond issues by governments and the aggregate of all types of green bonds at the country level seem to have a genuine impact on carbon emissions and ESG results.

At the company level, this is less clear if a specific green bond issuance has an impact. Investors should pay close attention to the quality level of the attached third-party certifications (if any exist to begin with) and the overall green credentials and track record of a given company before blindly believing the associated green claims.

Future Of Green Bonds

This likely indicates that green bonds are entering a more consequential phase of market development. Investors will from now on not just focus on financial questions, but also ask whether the capital actually produces additional renewable capacity, emissions reductions and green innovation.

Standardization of certification at the international level, with green-financing frameworks, third-party assurance, and demonstrable operating assets financed by green bonds, will go a long way in reducing fear of greenwashing and improving the impact of green financing.

This will also indirectly put pressure on companies using watered-down sustainability claims to escape their environmental responsibility, increasing further the real-world impact of green bonds.

Investing In Green Bonds

Brookfield Renewable Corporation

Brookfield Renewable is a giant in green energy generation, part of the even larger Brookfield financial conglomerate (BN ), which owns 48% of Brookfield Renewable. The company is accessible to investors through either the ticker (BEP ), a limited partnership, or (BEPC ), a traditional corporation, although the company is moving toward a single merged listing for a single publicly traded corporation.

The company manages 47,300 MW of renewable power capacity, with over 250,000 MW of renewable power assets and a development pipeline (mostly wind, solar, and storage).

Source: Brookfield Renewable

Besides renewables, Brookfield Renewable also owns 50% of Westinghouse, the US leader in nuclear power construction, which services ~two-thirds of the global nuclear reactor fleet, positioning it well into the other, non-renewable low-carbon energy technology.

It is also present in carbon capture, Sustainable aviation fuel (SAF), Renewable natural gas (RNG), and recycling.

The company’s main markets are North America, followed by Europe and Latin America.

Source: Brookfield Renewable

Brookfield Renewable utilizes its Green Financing Framework to issue green corporate securities and notes that fund clean energy generation, storage, and decarbonization technologies. In total, it issued 18 green-labeled corporate bond series in North America, exceeding $5B in total.

This aligns Brookfield with the ICMA Green Bond Principles, incorporates allocation and impact reporting, and provides for independent third-party assurance. This is precisely the type of green bond most likely to have a positive impact highlighted by this study. And the company’s long-established operational excellence in deploying renewable energy capacity also makes it a very credible green bond issuer, helping it raise money for the planned 5-fold increase in capacity in its development pipeline.

(You can also read more about Brookfield Renewable in our investment report dedicated to the company)

Latest Brookfield Renewable (BEPC) Stock News and Developments

Study Referenced

^{1. Peng Zhou et al. Green bonds and the energy transition: From instrumental use to intrinsic value. Energy Economics. September 2026. Article: 109503. Volume: 161. 10.1016/j.eneco.2026.109503}