The company responsible for London’s ‘super sewer’, Tideway, has become the first corporation in the United Kingdom to issue a ‘Blue Bond’ in Sterling. Blue Bonds are a subset of the better-known Green Bonds, and they are termed ‘blue’ to denote specific investor benefits to our seas and marine environments. To date, Tideway has issued 18 green bonds.
The term ‘green bond’ refers to a product which is not dissimilar to traditional bonds. They work in much the same way, except for one key difference: the money raised from investors in green bonds is used exclusively to finance projects that have a positive environmental impact- such as renewable energy and green buildings. The concept of green bonds has been with us since the start of the century; in 2007 we witnessed the issuance of the world’s first green bond by the European Investment Bank (the EU’s lending arm). Since then, many governments and businesses have entered the market to finance green projects[i].
The Tideway project (or the Thames Tideway Tunnel as it is formally known) is designed to intercept the tens of millions of tonnes of sewage pollution that has historically spilled into the Thames River each year. To date, it has captured more than seven million tonnes of sewage pollution, and since the tunnel was fully connected in February 2025, there have been zero sewage discharges from the spill points to which Tideway connected the new infrastructure.
The proceeds from the new £250 million 8-year blue bond will provide Tideway with additional liquidity for the project, which is due to be complete in 2027.
Announcing the news of the blue bond issuance, Tideway CFO Mathew Duncan said: “Tideway was one of the first to issue Green Bonds as the project was getting underway, and so it’s great to be building on that legacy with this latest issuance[ii]. He added: “With the super sewer now protecting the tidal Thames, including therefore the Thames Estuary and the North Sea, it’s wonderful to be able to offer Blue Bonds in the UK for the very first time. Blue Bonds emphasise the importance of the sustainable use and protection of water resources, highlighting the main purpose of the company – cleaning the river.”[iii]
Collectively, growth in the climate bonds market has exploded in recent years. Most recently, The Climate Bonds Initiative reported that climate bonds (all green, social, sustainability, and sustainability-linked bonds- collectively termed GSS+) reached $1.1 trillion in 2024 alone, with the cumulative total for this segment now standing at $5.7 trillion[iv]. The outlook for 2025 appears positive, especially given the increased visibility of green insurance following COP 29 last November. Further, the urgency in which adaptation and resilience spending is required will potentially unlock even greater levels of climate finance.
Caroline Harrison, Director of Technical Development at Climate Bonds said in a press release: “The GSS+ debt market continued to thrive in 2024. The year end market data was not only a huge source of encouragement and optimism but also highlights the opportunities for a broader range of issuers to deploy into the market in 2025. Updated NDC targets, new governments, and increased participation from insurance make ambitious issuance targets credible in the year ahead.”[v]
References
[ii] Tideway | Super sewer project becomes first UK company to issue Blue Bonds
[iii] Ibid
[iv] Climate Bonds | Climate Bonds Publishes Provisional 2024 Numbers and…
[v] Ibid
Lauren has extensive experience as an analyst and market researcher in the digital technology and travel sectors. She has a background in researching and forecasting emerging technologies, with a particular passion for the Videogames and eSports industries. She joined the Critical Information Group as Head of Reports and Market Research at GRC World Forums, and leads the content and data research team at the Zero Carbon Academy. “What drew me to the academy is the opportunity to add content and commentary around sustainability across a wealth of industries and sectors.”
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