Tackling the challenge of process emissions
10 November 2021
Tackling fugitive emissions is one of the key pillars of Welsh Water’s net zero strategy. Process emissions in wastewater treatment remain one of the more challenging areas to decarbonise and we’re still learning about the current level of fugitive emissions that arise from treatment processes.
Work is ongoing within Welsh Water and the wider UK water sector to improve the monitoring and reporting of such emissions, and from there we are researching technologies to run our sewage works differently to reduce the emissions themselves.
We spoke to Keeley-Ann Kerr, our Energy Analyst, to find out about a key project she’s working on to help minimise emissions. With a Masters in climate change, minimising the company’s greenhouse gas emissions is something she is incredibly passionate about. Read all about it, below.
So Keeley-Ann, tell us about the Cobalt Water project. How is it helping us reach our target of Net Zero?
The purpose of the Cobalt Water project is to help Welsh Water tackle its fugitive emissions, contributing to achieve a 50% reduction in process emissions associated with treatment of wastewater, sewage sludge and the disposal of digested sludge to land. This project is studying six sites, for one-month periods on each site. These findings will help us potentially build a business case to continue research on more sites across the Welsh Water catchment.
What are process emissions?
In the process of treating wastewater and biosolids, greenhouse gases are emitted due to the natural breakdown of waste within wastewater - mainly methane(CH4) and nitrous oxide (N2O). Nitrous Oxide is of particular importance due to its global warming potential (GWP) – which is up to 298 the times of CO2 over a 100-year timescale. GWP is a measure of how much energy the emissions of a gas will absorb so the larger the GWP, the more the gas will warm the Earth compared to CO2 over the same period.
Tell us more about the project
The main purpose of this project is to allow us to gain a greater understanding of what impact our process has on greenhouse gas emission production. It also allows us to understand what improvements can/should be made to improve our process, to reduce emission production and understand which measurement equipment is best suited for our needs.
The first phase of this study was selecting trial sites to collect and collate data of various parameters from our process which were input into a machine learning created by Cobalt Water. We are now in the second phase of the trial, that is installing the Unisense N2O Microsensors on our sites. The first trial is at our Swansea Bay WwTW. The sensor will be installed for a month, and the data collected will help to verify the machine learning and understand exactly how much N2O is being produced during the process.
What’s next for this project?
We will be moving the Unisense monitors to five other wastewater treatment works across Wales. Like at Swansea, they will be kept on site for a month to collect data and allow us to understand N2O production more. This will mean we can look at ways to minimise production of N2O within the treatment process.
Finally, what one outcome are you hoping for at Cop 26?
I hope to see some significant agreements and targets that start the systematic change to help tackle the climate crisis. No matter the outcome of COP 26, I encourage everyone to do what they can, no matter how small, as we as individuals can help drive these systematic changes even further.