Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/1202034
24 | FEBRAURY 2020 | WWT | www.wwtonline.co.uk The Knowledge: net zero through carbon sequestration projects. The carbon manage- ment hierarchy is always to reduce emissions first before trying to offset them because it is more cost effective. In simple terms, if you're burning less fuel, you're spending less money purchasing fuel." Net zero is a shared target for water companies in England and Wales and each entity is expected to imple- ment different carbon saving measures and solutions based on their own specific strengths and weaknesses. Yorkshire Water is hoping to exploit its large land real estate portfolio and work with tenant farmers and other significant landowners to promote more sustainable land management practices, including peatland restoration and tree planting. Liz Barber, CEO at Yorkshire Water, said: "It will be very difficult to com- pletely decarbonise without working in partnership with those in our region, thinking needs to be joined up both within the sector and beyond it." Anglian Water wants to exploit its renewable energy resources. During 2017-2018, as part of a carbon mitigation strategy, the company saved over 6.5 GWh of electricity and generated 106GWh of renew- able power from biogas CHP, wind and solar combined. David Riley, head of carbon neutrality at Anglian Water, told WWT: "We've got very ambitious goals around renew- able energy, we want to source 44 per cent of our energy consumption from on-site renewable resources." As with the other Public Interest Commitments, net zero 2030 will be subject to independent scrutiny and held accountable for incremental progress against incremental targets, details of which are forthcoming. Colville comments: "There's a big question of how we manage this commitment post-2020. We need to think through the management framework, we need data re- porting information, and some way of ensuring that we stay on track to satisfy independent scrutiny." Principal offenders Hitting climate targets means pinpointing and tackling the biggest sources of emis- sions. According to figures from Ricardo, grid electricity currently accounts for half of the sector's overall footprint, followed by process emissions related to water treatment and sludge disposal that comprise about 25 per cent. A›er that, various sources are broadly equivalent, such as transport and emissions from the direct use of fuel, like natural gas or gas oil. Look ahead to 2030 and the picture changes somewhat, the rapid decarbonisation of the national grid is expected to reduce related emissions to 30 per cent of the total, elevating the impact of process emis- sions to about half. Behling at Ricardo com- ments: "Decarbonisation of the grid will support the continued decarbonisation of power usage by the sector so energy going into pumps and treatment processes will become less carbon intensive over time. The sector is also investing hugely in renewable energy, both traditional renew- able generation such as PV and wind, and using biogas that comes off sewerage treat- ment processes much more efficiently." Bringing down process emissions will place a greater emphasis on technological innovation. UK Water Industry Research (UKWIR) launched a project in August, specifically linked to net zero, to develop a better scientific basis to quan- tify process emissions result- ing from water and wastewater treatment and disposal. A significant amount of carbon is locked up in more stringent EU environmental constraints and treatment processes required to re- move damaging chemicals like phosphorus from water. Whether the rules remain in a post-Brexit is uncertain, it is possible that regulations will change to favour natural habitat or biodiversity solu- Using anerobic digestion technology The next generation of super-efficient anaerobic digestion technology is expected to result from a research partnership between Yorkshire Water and the University of York. The water company aims to treat 100 per cent of its sewage sludge using anaerobic digestion from this year and make existing digesters work harder to process sewage into biogas for electricity generation. The project is backed by funding from the Royal Society and involved construction of 60 five-litre automatically fed, temperature controlled anaerobic digesters in the Department of Biology at the University of York (known as System-60), as well as a pilot-scale diges- tion facility at Yorkshire Water's wastewater treatment works at nearby Naburn. The laboratory environments will be used to investigate the microbi- al communities that drive digester performance and screen conditions, the pilot rig will demonstrate the benefits at a larger scale to build a case for operational changes across the water company's digester fleet. Improvements to anaerobic digestion would mean more sewage sludge is processed in the same facilities, reducing the need to build new infrastructure, whilst boosting levels of renewable energy produc- tion and generating a higher-quality fertiliser byproduct for farming. Professor James Chong at the Department of Biology commented: "The new facilities we've built allow us to mimic large scale installations and use state-of-the-art techniques to understand how the microbial communities that drive anaerobic digestion change in response to the material that enters the digesters." Yorkshire Water treats around 150,000 tonnes of sewage sludge using anaerobic digestion each year. Anglian's solar site at Jaywick is capable of generating almost 900 kWp.