In the same boat – international water partnerships to cut carbon

This is a guest blog from Severn Trent’s Net Zero Hub and Tapping into Sewer Heat projects, which were awarded funding in Water Breakthrough Challenge 3 and Water Breakthrough Challenge 4 respectively. 

The UK water sector faces many challenges that it must urgently solve, from achieving net zero emissions, to preventing leaks, ending the overuse of storm overflows, tackling pollution and adapting to the impact of climate change; all while ensuring customers are properly served. But the UK is far from alone. Increasingly there is collaboration on innovation across borders to find solutions.

In this latest blog in our series on international collaboration, we highlight the experiences of two projects – Net Zero Hub and Tapping into Sewer Heat – led by Severn Trent and include international partners. We explore what this international expertise brings to these projects, and how water companies can learn from work happening abroad.

Net Zero Hub

Severn Trent’s investment of £40 million in transforming the Strongford wastewater treatment plant into a Net Zero Hub including £10 million from the Ofwat Innovation Fund, marks a significant step towards their goal of net zero carbon emissions.

Severn Trent’s ambitious Net Zero Hub project marks a significant advancement in environmental technology, reducing greenhouse gases by building the world’s first net zero wastewater treatment hub and sharing its learnings with others. The partnership with Aarhus Vand in Denmark and Melbourne Water in Australia, supported by UK and Irish water companies, underscores the global commitment to sustainability, of which Severn Trent are taking a leading role.

Innovative suppliers are developing technologies to reduce, remove and avoid carbon. The aim is to integrate the most promising technologies on one site for the first time – creating the Net Zero Hub – trialling them at scale to deliver a blueprint for water companies to retrofit their own wastewater treatment plants. This has included:

• Partnering with Suez, the Actilayer system was developed to cover and treat nitrous oxide emissions from proof of concept to full-scale installation at the Net Zero Hub via intensive research and development at our Resource Recovery and Innovation Centre (R2IC) and Suez’s own development facilities in Paris and Nantes. Through the trials, Actilayer was proven to treat emissions of nitrous oxide, a gas that represents most direct emissions from wastewater. Nitrous oxide has nearly three hundred times the global warming potential of carbon dioxide and is roughly nine times more potent than methane.
• Working with Atkins Realis and JN Bentley the design and construction of the Net Zero Hub has employed innovative construction approaches such as 3-D printed concrete and streamlined assurance processes to ensure rapid delivery.
• The installation of advanced monitoring systems for greenhouse gases, including nitrous oxide and methane, enables real-time tracking of emissions, establishing a blueprint for future environmental monitoring.

The power of collaborative innovation

This initiative is not just a leap in technological advancement but also a testament to the power of collaborative innovation. By transitioning from concept to full-scale application, the project exemplifies a shift towards sustainable practices within the industry. The blueprint developed offers a comprehensive strategy for emission quantification and introduces cost-effective retrofit solutions, aligning with the ambitious net zero targets set for 2030.

The project’s inclusive approach, sharing knowledge with utility partners and the global community, enhances its impact. Severn Trent has published an open access documentary and shared knowledge at conferences and in trade journals. These serve as educational tools, demystifying complex technologies and promoting widespread adoption of emission reduction strategies. As the project progresses, this commitment to disseminate findings will empower other water organisations to embrace this model, fostering a collective movement towards net zero goals.

Severn Trent’s rigorous evaluation of over 50 technologies to identify the most cost-efficient solutions highlight the proactive measures being taken to overcome financial barriers associated with carbon reduction technologies. The development of digital twin technology further augments this process by enabling precise simulation and optimisation.

The forthcoming industrial-scale deployment at the Net Zero Hub promises to provide tangible, verifiable data, bolstering the industry’s efforts to minimise its carbon footprint. This integrated approach not only addresses current environmental challenges but also paves the way for future innovations in carbon reduction.

The Net Zero Hub stands as a beacon of progress, guiding the industry towards a more sustainable and responsible future. Severn Trent will continue to share the outputs, enabling other water organisations to apply this concept and support their net zero journey.

For more information on this project, check here.

Tapping into Sewer Heat

The UK government has set ambitious targets for heat decarbonisation as part of its broader commitment to reduce greenhouse gas emissions and combat climate change. The UK water companies treat approximately 11 billion litres of wastewater every day which theoretically results in nearly 400 TWh of renewable heat that could be recovered (enough to heat 33 million homes). However, the heat available in wastewater remains a largely untapped resource, with reluctance in the UK to exploit this heat resource due to:

• fears around installing equipment in sewers – leading to the potential for increased risk of blockages, and
• the lack of district heating infrastructure which is needed to make treated effluent heat recovery a viable option.

Although using wastewater heat seems like a great solution – it requires validation, not just from a carbon perspective, but from an operational, societal and commercial perspective too.

There are isolated examples of sewer heat recovery (not direct in-sewer) and treated effluent heat recovery in the UK, albeit of different designs to that proposed for this project. For example, Scottish Water Horizons have installed technology at Borders College where sewage is pumped out of a sewer, the rags removed and returned to the sewer and then the flow directed to a heat exchanger, and Scottish Water and Anglian Water have a few final effluent heat recovery systems.

It’s unlikely that wastewater heat recovery will gain traction without further development of both the technology to maximise the efficiency and the commercial model, which needs to stand without incentives.

This project will install a first-in-the-UK in-sewer heat recovery technology with a novel heat distribution model, with a water utility, an energy utility and an industrial off-taker working in partnership to accelerate the deployment of wastewater heat recovery in the UK.

Eon has a two-year track record of in-sewer heat recovery in Germany which has shown that these systems have the significant advantage over effluent heat recovery as the source of heat can be immediately adjacent to the heat demand.

This project will demonstrate that recent developments can effectively mitigate the risk of blockages, improve the economics and deployability and will represent the first time that these technologies have been combined. This project has been designed to gather the evidence to properly assess this risk and provide clear guidance on any mitigation necessary.

For more information on this project, check here.

Catch up on the previous blog in this series ‘World in motion – bringing innovation to life through international collaboration‘

We look forward to hearing from more projects in the Ofwat Innovation Fund who are looking to import innovations from around the world into the sector. Please reach out to us should you want to showcase your project and its ambitions.

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If you’d like to speak to us about the fund and future opportunities, the Ofwat Innovation Fund will be exhibiting at the following events over the next few months:

• Wastewater 2025 Conference & Exhibition, 28-29 January 2025
• WWT Innovation Summit, 25-26 February 2025