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UTILITY WEEK | 6TH - 12TH MAY 2016 | 21 Sponsored report Case study " Power from poo: How Northumbrian Water slashed its energy bill The things we're doing are not novel, but how we've applied them is a little bit different. Water and wastewater are heavy to move, so every time you add another process unit, you're adding more cost into your value chain, and using more energy. Our annual energy bill is £40 million, and treating wastewater accounts for more than half of that. We take 100 per cent of our sludge and turn it into energy. We very deliberately talk about this as 'power from poo', to help our employees, our customers, and our stake- holders understand what we're doing. When you are asking your customers to support a massive shi in strategy, and spend £35 million building a new plant, it's really important that they buy into it and understand it, and for us that's been incredibly successful. We treat 2 million m 3 of sludge each year and generate 10MWh a day of electricity. That's enough to power 30,000 homes. We reduce that 2 million m 3 of sludge down to about 150,000 m 3 of sludge, thus reducing the cost of energy required for transport. Digestion's been around a long time, but our approach has been a little bit dif- ferent. Our focus on every wastewater treat- ment work is to maximise the amount of sludge we produce. We have 430 treatment works and take all the sludge into six hubs for de-watering, and then to two industrial- scale plants. Having it on such a large scale, and thinking about it regionally and strategi- cally, has allowed us to get as much energy as we possibly can out of sludge, ultimately reducing our overall electricity bill by about 20 per cent. Anaerobic digestion is great for freeing energy from sludge, but it's only about 45 to 50 per cent effective in terms of energy recovery. It's far more effective to take that gas and put it straight into the national gas grid. We're putting gas into the grid equiva- lent to powering 7,000 homes. That has helped us to drive another £3 million of effi- ciency. Ultimately all these things help to keep our bills low. There is huge potential to reduce the cost of pumping water, to make more of our reservoirs, to pump when energy is cheaper, and to make the most of the cheapest water sources. Managing that is incredibly com- plicated. A couple of years ago we took a very brave step to stop our people operators from managing our water network and to give all of that control to a computer sys- tem. Our operators found that to be a mas- sive challenge in terms of cultural change. We now have 28 treatment works, 64 pump- ing stations, 97 service reservoirs, and a plethora of control valves operated by a system called Acrobat. If a part of the plant fails, or we take something out or have an incident, it rethinks and makes sure that we're always operating at an optimal level. That's helped us to drive down energy bills by £1 million a year. We didn't stop there. We've worked with researchers at Sheffield University on discoloured water, diving efficiencies and improving the quality of water in custom- ers' taps. Working with Newcastle Univer- sity, we've had a trial plant running for a year, the first in the world to run on real waste water, and it has produced hydrogen throughout that year. If we can tap into that energy inside wastewater and derive hydro- gen as a clean fuel, it has the potential to be a game changer." Maxine Mayhew, Northumbrian Water Group commercial director Brought to you in association with Northumbrian Water Group Fast facts: 2.7m water and wastewater customers in north of England 1.8m water customers in Essex and Suf- folk £40m annual energy bill 2m cubic metres of sludge each year 100% of sludge turned into energy 20% reduction in energy bill owing to anaerobic digestion 10MWh a day generated, enough to power 30,000 homes Power from poo: Northumbrian Water Group uses simple messaging to explain to customers how it is transforming the business by turning sludge into energy. Pictured is Bran Sands sewage treatment works Teeside, complete with anaerobic digesters.