North West water company United Utilities is well on the way to building a “virtual power station.” Energy manager Andy Pennick describes how getting smarter with energy use can pay dividends and boost green credentials.
We know that energy is one of our biggest costs so our mantra is to use less, generate more and use our assets smarter. We’ve done a lot of work already on installing more energy-efficient equipment and we’re generating some 18 per cent of our own electricity through biogas and other renewable sources. But it was the “getting smarter” that led us to trialling Dynamic Demand, a dynamic frequency response solution offered by Open Energi.
Water companies are ideally placed to make use of frequency response. Certainly we use a lot of power, but often we can be flexible about when we need to use it thanks to the storage available in our assets.
Take clean water pumps for example. Some service reservoirs have many hours of storage and the pumps don’t necessarily have to operate immediately when water levels start to fall. Another good example for wastewater is the air blowers on activated sludge plants. When managed, there’s headroom available in the process that allows for flexibility in precisely when the air blowers need to cut in, especially suitable for those with variable speed drives.
In 2014 we decided to trial Dynamic Demand at three sites, Hoghton water pumping station, Bolton Wastewater Treatment Works and Birkenhead Wastewater Treatment Works.
What are the challenges?
It was easy enough to identify the types of site and process that would lend themselves to Dynamic Demand, but one of the biggest challenges we faced was persuading our operational teams that it was a good idea!
The top priority for our employees is maintaining compliance. We had to create a cultural shift so they were prepared to accept handing over some control of our processes. We did that by sitting down with the operators involved and working through the numbers in extreme detail.
HazOp is a risk-based analysis tool we use to brainstorm all the things that could possibly go wrong on each site where we planned to trial the technology.
This allowed us to set safety margins within which the equipment could respond to changes in frequency. Once outside those margins, the process takes priority again. It does require a certain trust in the solution and that was the most difficult obstacle for us to overcome.
We know that energy is one of our biggest costs so our mantra is to use less, generate more and use our assets smarter.
To date we have installed the technology at 10 of our larger activated sludge plants, (biological wastewater treatment) including Davyhulme in Manchester, St Helens, Preston, Runcorn, Warrington and Widnes. We have also successfully integrated Dynamic Demand onto other sites, for example a water pumping station. Over the coming months we are targeting a further 10 activated sludge plants and have started to evaluate new waste and fresh water processes that we feel would work with the technology.
We are also embarking on a programme with Kiwi Power to automate our back up diesel generators for deployment in the STOR market alongside working on DSR trials with our local DNO, Electricity North West.
Our aim, by 2020, is to provide access to 50MW of Demand Side Response for National Grid – enough to displace a peaking power station. I think that’s a very tangible ambition, and it shows there’s real potential for the water industry to help build a sustainable future UK energy market.