Dale Foster, Business Development Manager at wastewater technology specialists HUBER Technology, explores why water companies and urban developers/ built environment owners in the UK (exceptions in Scotland) have still not embraced the potential of using thermal energy from wastewater for renewable energy generation and as a source of potential revenue.

Dale Foster: In this article, I’d like to take a look at what is still currently a largely untapped opportunity for wastewater energy recovery- which even now to date the UK still has yet to take advantage of. It’s arguably the most obvious and abundant renewable.

For some time now, the impacts of climate change, security of energy supply, rising energy costs, pressure on both individual and organisational expenditure, household bills, spending power, household budgets, costs of doing business, drive to net zero, have been high on the agenda in the UK. They will continue to be so for some considerable time to come.

Readers who follow technology news in the press may have seen an article in The Guardian newspaper last week saying that sewage waste is now being seen as a reliable heat source for millions of homes in the Netherlands.

With a typical temperature of 10°C - 25° C, all year round and a yearly average of 17° C, unlike intermittent energy sources like wind or solar power, municipal or Industrial wastewater is a hidden and seldom used source of energy running through the sewer network. The other major benefit compared to established renewables is that most of the infrastructure already exists, is mainly out of sight below ground and the greater the population the greater the energy available.

Constant supply of wastewater 24/7 - ideal, uninterruptible energy source for heating and cooling buildings

Image: Typical urban area & buildings marked that could benefit from this technology

This constant supply of wastewater is available 24/7, making it an ideal, uninterruptible energy source for both heating and cooling buildings.

According to the Water Environment Research Foundation (now part of the Water Research Foundation), wastewater contains nearly five times the amount of energy needed for the wastewater treatment process – the majority in the untapped area of thermal energy.

So the key question for me, which I’m still puzzling to find a meaningful answer to is why an energy resource which has been accepted and used to great effect for decades overseas has failed to see any discernible uptake in the UK. Wastewater heat recovery technologies are a proven solution and have been widely adopted elsewhere – but not here.

Just to take our own patented HUBER ThermWin® technology as an example, this is now installed in over 40 locations globally. Examples include a wastewater energy recovery system which has been operating in Straubing in Germany since 2010. The system covers 102 apartments in total spread across five buildings. In Winterthur, Switzerland, another system which has been operating since 2011 provides 480kW of heating and 840kW of cooling to a 28 story office building. The HUBER RoWin® heat exchangers can either add heat to the building’s own systems or take excess heat away from the building and into the sewers to help cool the building.

Why has this tried and tested technology not been brought into more widespread use in this country?

So given its demonstrable advantages and benefits, why has this tried and tested technology not been brought into more widespread use in this country?

A brief run through of just a few of the benefits might also get other people thinking about the same question.

Firstly, it doesn’t require massive upfront capital investment – it simply taps into and capitalises on the existing infrastructure, processes and systems which are already in place. England alone has some 350,000 miles of sewers.

It is a decentralised potential energy source available at a local level – it does not have to form part of a larger strategic grid, but can do.

In the context of climate change, this solution can be used in residential environments for heating purposes in the winter and cooling in the summer as we face the prospect of increasingly frequent heatwaves. In commercial buildings (offices, leisure centres and many public buildings etc.) the tendency is that after initial heating, cooling is required for most of the rest of the working day.

What are the perceived barriers preventing uptake?

So what are the perceived barriers preventing uptake? There are three broader issues in particular I’d like to open up to further discussion.

Firstly, whether the focus on innovation is distorting the landscape at the expense of making the most of what’s already there. The water companies are all facing common problems and challenges. There are a lot players in this space – Ofwat’s innovation fund, The Carbon Trust, Innovate UK, UKWIR to mention just a few. However, innovation isn’t always about the latest novel technology, treatment process. Sometimes it can be simply be about looking at what’s already there in a new way.

Secondly, there are a lot of organisations operating in the built environment space which can lead to a siloed approach to planning decisions – rather than taking a systems thinking approach and considering the challenges in a holistic way. Moving towards a circular economy has a key role to play on the path to Net Zero and energy recovery from wastewater could make a significant contribution - from which new housing development, commercial buildings, industrial complexes, public sector buildings, Smart Cities etc could all stand to benefit.

Thirdly, and going forward, whether optimising energy recovery from the regulated companies’ existing assets should properly be regarded as part of the water companies’ core business of providing water supply and sewerage services to their customers.

Regulation could play a useful role in encouraging greater uptake

One of the counter-arguments put forward in the past to adopting this approach has been that it doesn’t square with Ofwat’s insistence that the water companies should focus on these core business activities. In my view this approach doesn’t really necessarily deliver the optimum benefits it can provide to their customers.

In an increasingly funding, resource and energy-constrained world grappling with the serious challenges of climate change, maybe a rethink is now needed on broadening the definition of these core business activities.

This is an issue which I really feel would stand to benefit from opening up to wider discussion beyond the water companies themselves. Raising awareness of the potential of energy recovery with a wider audience - local authorities, planners, architects, consulting engineers, structural engineers, facilities management organisations, and renewable energy providers - has a key role to play.

Regulation could likewise also play a useful role in encouraging greater uptake – I’m thinking here of the phased approach taking to introducing SuDS. Initially introduced as an option for using sustainable drainage to be taken into account by builders, developers, planners and architects, the benefits of SuDS have finally been recognised.

First introduced in the Flood and Water Management Act 2010, the decision to make SuDS mandatory by 2024 with the implementation of Schedule 3 of the Act was announced by DEFRA at the start of this year.

To sum up, I’m as interested in finding out why people think using technology for wastewater energy recovery won’t work for them, as from the people who think it will and want to know more about what’s on offer and how they can incorporate into their own developments.

If anyone would like to have a wider discussion and explore the issues further, contact Dale at This e-mail address is being protected from spambots. You need JavaScript enabled to view it or Mob: 07980 316059.