Draining Carbon From Wastewater Networks

According to the Environment Agency, over 10B litres of sewage are produced every day in England and Wales. To treat this volume of sewage requires approximately 2,800GWh of energy, equating to 1.7M tonnes of greenhouse gas emissions. And of course, that’s only the operational carbon footprint…embedded carbon is quite another matter!

No one is underestimating the size of the challenge facing the water industry when trying to address the increasingly urgent issue of carbon footprint reduction in wastewater collection networks. Regulatory demands mean that water companies must reduce their operating costs by 15% by 2015 is part of UK Plc’s climate change responsibilities. As a major energy user, the water industry must start scrutinising its energy-intensive processes, systems and equipment to deliver an effective approach to energy reduction. To encourage and enable debate and thoughtleadership on this topical issue, WWT hosted a gathering of industry minds at the Institute of Directors’ impressive headquarters in Pall Mall.

Sponsored by ABS Wastewater Technology, the event was chaired by Professor Tom Stephenson, head of the school of applied sciences at Cranfield University and adviser to the board of BluewaterBio.

The directive for the round table event was clear, to probe what actions water companies are taking to enable carbon footprint reduction in wastewater networks, what barriers they face, and how they believe the process can be accelerated.

The first point put to the panel was whether water companies have the necessary drive to stimulate the ‘right levels’ of activity that can underpin reductions in carbon emissions? To add extra weight to the question, Stephenson pointed out that 90% of water/wastewater costs are attributable to the underground asset, highlighting the scale of the carbon footprint challenge. First to take the baton was Paul Fisher, design & build standards manager – wastewater service at Severn Trent.

“I think the industry has already achieved a lot regarding the issue of carbon reduction but clearly we can do more,” he said, a sentiment met with nods of agreement. “Energy use at water companies has escalated 100% since 1990 and this is simply not sustainable. We include energy usage in all our cost benefit analyses now – everyone wants to see less energy consumption, not least our investors.”

Today, virtually every company’s Strategic Direction Statement will cover the issue of energy efficiency and carbon reduction targets. Certainly at UKWIR, carbon reduction and energy efficiency is one of the key research themes in which the industry is investing as part of its innovation roadmap.

“Due to the Climate Change Act there is little doubt that sewerage assets will come under pressure,” said Stephen Bird, operations director at South West Water. “It’s vital that we examine how to best use the capacity of the existing sewage asset network before we start building more storm storage attenuation. Factors such as real time control and smart operation pumping stations are fundamental drivers.”

Matthew Pluke, energy manager at Anglian Water, supported these comments, adding that creating the right level of drive was easy as the business, social and environmental reasons all pull in the same direction.

Yorkshire Water’s asset strategy manager, Ben Roche, said his company’s efforts (backed by customers and stakeholders) were very focused on carbon emissions. However, he added that this focus was very much on operational, not embedded carbon for now, largely due to financial constraints.

“On the network side we’re in a catchup phase,” added Steven Wilson, head of wastewater at Welsh Water. “We need to think carefully about storage, spill frequencies andwhere the carbon debate takes us regarding big storage solutions, which have a lot of embedded carbon, versus other options.”

According to Sarah McMath, head of asset planning, optimisation & innovation at Thames Water, the big challenge so far has been around data and understanding where network energy is being used. Until this is understood, she suggested, it is hard to have a high level strategy to drive reductions. As

a result, the approach at Thames Water has been on automated meter reading at sewage pumping stations across the company’s whole estate. “We also need to think about going back upstream,” said Fisher. “At the moment we have to treat everything that flows in our direction. The industry needs a more holistic approach to catchment management.”


With other drivers such as the carbon tax and schemes like Ofwat’s Service Incentive Mechanism (SIM), as well as incentives to address the customer experience around flooding, there is clearly a desire for more efficient operation of wastewater networks, a point put across by Bird, whose comment was followed by a succinct statement by McMath.

“If 80% of our energy costs are on pumping, common sense says that if you reduce the amount of sewage being pumped you reduce your costs and, therefore, your carbon,” she said. “Within Thames we have water efficiency under the same management area as energy and carbon because we see those two absolutely linked; they are both about optimising resources and minimising waste.”

It is a salutary point and everyone concurred with the logic, including Pluke, who wanted to introduce the topic of blockages to the debate. “We need to be talking to our customers about what they shouldn’t be flushing down their lavatories because reducing blockages will also lead to energy efficiencies. Even the best available pumps still block.”

Charles Gaisford, principle consultant at SKM Enviros, outlined recent research he had undertaken for Defra that examined the lifecycle impact of pumping stations. The work highlighted the trade-off between reliability/ pollution risk and efficiency, and also the issues surrounding non-flushable products. Of course, everyone in the industry is aware of the main offenders when it comes to flushed undesirables: disposable baby wipes, latex contraceptives/gloves, paper hand towels, sanitary products and cotton wool buds all appear on the least wanted list.

“As a pump manufacturer we spend a lot of time and effort on our latest range of products to make them more resistant to blocking, because the blockage-free pump hasn’t been invented yet,” said Clive Patten, managing director, ABS Wastewater Technology.

The point was made that in the event of a sudden storm, everything gets washed down the drainage network, and the impact of grey water on wastewater collection systems is considerable.

“Yes, ultimately we need a set of assets that are transmitting sewage to treatment facilities and as little rainwater, infiltration stream water and highway drainage as possible, in a system that is 60-70% combined,” said Bird. “I accept it’s a challenge and it will probably take 30/40/50 years, but we need to get going. Some have made a start in this current five years; some of us will have integrated urban drainage approaches. I suggest it will probably pick up the pace, particularly ahead of the climate change adaptation challenge.”

Bird also wanted to make a point about blockages. “In light of recommendations made by the Pitt Review and the Flooding Act we must work closely with the EA and local drainage authorities to understand the complexities of combined systems. We are undertaking some joint working in Torbay to identify misconnections where there is a mix of waste that can cause pollutions and problems. If you solve that, it will improve network efficiency.”

Ultimately the carbon debate is about attitude and the trade-off between profitability in the short term and sustainability in the long term.

“If you want to be ethical and conserve what will be a scare resource in the future, then good leadership will promote growth through your influence – because you are credible – then growth in terms of business because you are influential,” said Roche.

After the corporate viewpoints had been aired, Stephenson asked whether the Government and regulators should provide incentives for water companies to invest in energy saving technology.

“The short answer is yes,” said Pluke. “The EA has done good work regarding embedded carbon calculations in certain projects – the regulators are open for discussion about incentives and we need to work with them.”

Ofwat’s infrastructure serviceability measures are key incentives, and this point was ably made by Bird, who added there were plenty of mechanisms to focus attention on the effect of operation and maintenance to the network.

“I’m unsure about regulators driving incentives – they certainly drive challenges,” said Roche. “In the past few years we’ve had six or seven changes to energy and carbon type legislation incentives. This is a very volatile area and it does little to encourage a culture of timely and effective response, given a five year investment cycle that is fixed in terms of capital investment.”

“We are not lined-up enough with the regulators regarding quality schemes,” agreed McMath. “We’re sometimes driven down a route that is almost non-negotiable on quality, which potentially means energy and carbon reduction comes way down the list of priorities.”

The industry appears to be caught between a rock and a hard place, where on one hand it has to respond to calls for greater quality, and on the other for reduced energy consumption. Herein lies the dual challenge, since increased water treatment is likely to result in some increase in carbon emissions. Yes, technology can help, but both Fisher and Bird were agreed that there is a cost risk associated with innovation; that not all adopted technologies will give the anticipated outcomes in terms of carbon reduction or functionality in terms of flooding risk, and this should be more closely considered by regulators if water companies are to meet carbon reduction targets.

From here, Stephenson wanted to push the thought train towards innovation, asking what kind of technology is required, and which areas most need investment to help reduce energy consumption.

“There is clearly a need for innovation, but not always in a conventional way,” said McMath. “For instance, at Thames Water we’re looking at the hydraulic modelling and operational management of networks. If you have level and flow monitors within the network and you have very good hydraulic models you can start to make daily decisions on moving sewage around, instead of just accepting that it simply flows to a sewage works. There are good opportunities for efficiencies in this area.”

Gaisford was keen to outline the difficulties of measuring the performance of pumping stations, particularly regarding the efficiency of certain sections of the network. Here, determining best practice appears to be open at the moment – with industry divided about the most effective way to rate and benchmark these systems.

“Technology is great but the key issue relates to people, i.e. up-skilling,” added Fisher, introducing a new theme for debate. “As an industry we seem to have forgotten some of the things we did 15 years ago. Yes, we need to consider the right technology and the right processes, but let’s not forget to ask if people have the right skills. At Severn Trent we’re on a journey to encourage our people because they can, inevitably, be blockers.”

“Yes, there’s plenty of existing innovations, but I agree it’s also about educating the people who operate these technologies and helping overcome resistance to change,” said McMath. “Introducing a new pump can be journey for an operator if they’ve used the previous model for 15 years. But by giving data and information, and making that part of what they are monitored on, you start to get a very different operational response. For instance, at Thames Water we recently moved one of our operations managers to head of energy and carbon, and as a result we’ve seen a step change in the way we’re running our pumping station – that’s very much about people.”

“At Welsh Water we’re also starting to see greater response, having given operations managers more data on their pumping station network,” added Wilson.

“Innovation is vital, particularly long term, but there’s enough to be getting on with now in terms of the capabilities we have within our people,” said Pluke. “We have capabilities within our suppliers as well, which we can pull on, so there are enough immediate opportunities to go and make energy and carbon savings now.”

It is well documented that most water companies have taken advantage of the combination of real time control linked to SCADA systems into control centres. They also have experts who can review thermodynamic testing online, review CDN type information and plan preventative maintenance, which can be based on mechanical failure risk or on moving away from the optimum energy efficiency curve.

“In terms of technology we are often guilty of focusing solely on large equipment,” stated Bird. “If someone developed a ‘cheap as chips’ equivalent it would probably get introduced to every small pumping station without hesitation. Ultimately more can be done to increase the efficiency of the technology we have, to make it cheaper. We could then use real time control and SCADA/smart systems to sort the wheat from the chaff about which assets you ask your experts to look at in terms of energy efficiency.”

Despite calls for increased innovation and more enabling technology, Patten silenced the table with the claim that (as a technology supplier) he experiences very little ‘pull’ from water companies and that the onus is all on ABS to ‘push’ new products and press for trials.

“That’s amazing, that fact – as a supplier of energy efficient pumps to a sector where around 80% of the industry is pumping, there isn’t much pull,” said Roche, emphasising a general feeling of disappointment shared by the delegates.

“Perhaps frameworks have something to do with it,” added Patten. “Sometimes water companies have a set framework with a current supplier and we come along with something we would like you to trial and it’s difficult to break in.”

While the table reflected on the apparent lack of industry ‘pull’, Stephenson deemed the point had been adequately made and took the opportunity to advance the discussion. He drew a comparison with the automotive industry, and a case study some 15 years ago where a large auto OEM introduced a formal way to see if the whole supply chain was innovating. Does anyone here have this kind of procedure, he asked?

“It’s a good point and certainly a challenge for us all,” said Roche. “At Yorkshire Water we have no hard measures or contractual stipulations, but what we do have is belief. All of our suppliers must do more than simply hit their performance targets – they must innovate or it’s the end of the relationship.”

“Previously it was about compliance or energy/carbon savings – and which mattered most. But now the ethos is changing, it’s about compliance and energy savings – you must do both, and this can only happen with innovation from supply chain partners,” said Pluke.

Stephenson pitched a theoretical question to the panel, asking what technology they would most like to see, if given a green field ‘canvas’? The viewpoints returned were varied, and while all are some way from becoming reality, none are distant pipe dreams.

“We need to think about technologies that give us the benefits of good, old fashioned gravity,” remarked Bird. “Things like the deployment of permeable materials in urban infrastructure assets; if people are going to pave over their gardens then for goodness’ sake use permeable materials.”

“We’ve had some R&D schemes looking at the potential to use the inherent energy in effluent discharges and in CSOs,” added McMath. “It’s small and I’m not sure there’s enough power behind that at the moment. From a technology perspective something smart that could take that inherent energy instead of shed loads of sewage going into a river would be very interesting.”

“Asset condition is another area,” added Bird. “It would be nice if technologies such as ground penetration radar advanced a little. This would be a massive boost compared to deploying endless CCTV down manholes to check asset condition.”

Most supported the need for better, more focused data, and perhaps this is the biggest stumbling block to genuine progress. “In terms of ICA [instrumentation, control and automation], for me the ‘I’ is the really important thing – to know what instrumentation you need and what parameters need to be measured,” said Fisher. “Until we fully understand that, then we are tilting at windmills to be honest.”

Stephenson cited the possible presence of DRIP (data rich, information poor) syndrome in the industry, suggesting that a more formal link between water companies and manufacturers might help identify and drive innovation and energy solutions in this area.

“At Anglian Water we’ve worked hard to develop our supply chain relationships,” said Pluke. “In the recent past we shared our top10 ambitious goals with our supply chain, two of which were about carbon reduction, and invited manufacturers to help us develop joint business plans to solve the issues. We’ve been working with ABS since 2007, since when we’ve saved around £700,000 in energy costs.”

There are clearly gains on offer from closer collaboration with technology providers and Stephenson asked whether anyone had thought about a strategy shift on asset management – have they asked suppliers to provide lifetime asset maintenance rather than owning their assets outright?

“We’re still getting to grips with what the true life cost of ownership is,” said Fisher, “and I’m sure our key suppliers can help us do that. We certainly need more collaboration with suppliers; to really understand whether we should be refurbishing, whether we should be maintaining or replacing a particular pump at any one time.”

Having listened to the viewpoints on offer, Stephenson invited each delegate to state what single thing could affect the biggest change for carbon reduction.

“The way forward for UK Plc is about strategic partnering and new technologies to maximise the available capacity and assets that are already underground and have been doing us proud since the Victorians put them there,” stated Bird. “But before we’ve cracked that, I personally wouldn’t advocate pouring an awful lot more concrete or installing more online or offline storage tanks.”

“Our 2050 view on waste infrastructure has to be about ‘sewers for sewage’ and the benefits will be carbon. However, it’s going to be a long, progressive journey,” said Roche.

“Yes, there’s going to be some quick wins, but along the way there will also be some big ticket items, especially concerning the flooding agenda, which is very much in the public mindset.”