THE NET ZERO CHALLENGE
The UK water industry has set out its roadmap to achieve net zero carbon emissions by 2030 -
https://www.water.org.uk/routemap2030. Key greenhouse gases emitted by the water industry include carbon dioxide, methane and nitrous dioxide. However, not all greenhouse gases (GHG) have the same global warming potential (GWP). Methane has a GWP 27.2-29.8 times that of carbon dioxide, whilst for nitrous oxide the GWP is even higher at 273 times that of carbon dioxide for a 100-year time frame according to the International Panel on Climate Change (IPCC) in 2021. Direct emissions from sludge and wastewater treatment account for the majority (70%) of gross carbon emissions from the water industry, so reducing these scope 1, operational emissions is the main focus of efforts. Sludge treatment is the biggest source of methane emissions, and wastewater treatment is the largest source of nitrous oxide emissions.
Taking United Utilities as an example; in response to the Water UK roadmap UU has pledged to reduce scope 1 and 2 emissions by 42% by 2030 with a 100% reduction by 2050. (Scope 2 emissions are indirect GHG emissions associated with the purchase of energy, so can be addressed by purchasing certifi ed renewable electricity and/or installing renewable energy generation on site.) It makes sense for companies to go fi rst for the big, quick wins: “Currently in our pilots we are targeting nitrous oxide monitoring on the secondary treatment stage as this has the biggest emissions,” explains Richard Bragg, Principal ICA Engineer at United Utilities, “for methane emissions monitoring is focussed predominantly on the sludge process, on secondary digestors and open sludge tanks further down the process”.
Currently the industry uses Carbon Accounting Workbook emissions factors to estimate methane and nitrous oxide release from wastewater and sludge treatment processes. This means there is limited monitoring activity across the sector and a growing recognition that the sector must measure these emissions to develop effective management techniques. A recent review of monitoring activity across the sector by Richard Smith, Wastewater Innovation Architect at Severn Trent Water, is summarised in the fi gure below. It illustrates where GHG are currently monitored, where leaks are detected and where there is currently no monitoring of GHG and shows there are opportunities for the adoption of new monitoring technologies. A few available technologies that can assist the water industry with reducing GHG emissions are listed in Table 2.
“Nitrous oxide monitoring is currently focused on the aerobic suspended growth process,” admits Richard Bragg, “we don’t yet monitor nitrous oxide emissions upstream or downstream of this, such as monitoring biofi lters which serve a large proportion of
Table 1: Opportunities to improve monitoring of GHG emissions in the water sector ©Richard Bragg, 2021
Improvements are needed for monitoring GHG in the water sector in terms of:
• Sensing technologies for GHG • How to measure GHG in open spaces and in soluble form • Validation of GHG emissions • Optimisation of GHG emissions from processes • Predictive monitoring of GHG (PEMS)
• Relationships between GHGs and known process variables (surrogates) • Sensor suitability for GHG • Operational expenditure (OPEX) for GHG sensors • Future legislation and best practice • Funding routes
• Scalability of sensor solutions
Figure 1: Current monitoring of GHG, leak detection and processes which are not currently monitored for GHG in wastewater treatment © Richard Smith, 2021 Severn Trent Water.
the population.” For methane monitoring, the focus is currently on leak detection from sealed tanks, using existing technologies such as thermal imaging, using camera systems and optical methods. There are many more technologies that are not being used yet. Richard Bragg has identifi ed various ways that monitoring GHG emissions could be improved, which innovators could address when developing new technology solutions (Table 1).
Another opportunity for innovators is to address the level of uncertainty in whether GHG emissions can be reduced in the water sector - estimated to be 30%. There is a need to reduce this uncertainty by better quantifi cation of GHG emissions from
the sector. Also the Water UK route map assumes that nitrous oxide emissions can be reduced by 40% by adjusting operational processes, but there is uncertainty around whether this fi gure can be achieved. In the near future, Richard Bragg predicts that GHG monitoring will be further improved through the use of innovative technologies, novel sensors, non-contact sensors, imagery, AI, machine learning, modelling and applying the data as a service model in the water sector. Most water companies have an innovation team that is happy to engage with innovators. United Utilities has an Innovation Lab which welcomes approaches about new technologies.
Table 2: A few technologies on the market that help water companies to cut carbon emissions Technology Carbon emissions reduction Nitrate and nitrite monitoring • Real time monitoring
• Enables optimisation of biological nitrogen removal processes • Reduce energy intensive aeration requirements and related carbon emissions
Nitrous oxide sensor
• Real time, online monitoring of N2 • Able to monitor where and when N2
O O is produced and lost
• Enables climate friendly control for oxygen and carbon demand (ammonium turnover and COD/N ratio) • Enables process control to minimise production of N2
O Bio-electrode sensor
• Real time monitoring of exoelectrogenic microbial activity • Enables quantifi cation of microbial activity to improve understanding • Enables energy optimisation • Operators can turn off Biological Aerated Flooded Filters (BAFF) during periods of low microbial load – can lead to savings of 10-20% per site or £50k - £100k of energy costs (subject to the unit cost of energy).
Rosa Richards is an Environmental Consultant and Programme Manager of SWIG specialising in water policy and monitoring. She is Programme Manager of the Sensors for Water Interest Group (SWIG), and a freelance writer of science and technology. This article is based on a SWIG/KTN Sensor Sprint webinar held on 24 November 2021.
www.swig.org.uk
Author Contact Details Rosa Richards, Environmental Consultant and Programme Manager of SWIG • Bristol • Tel: 01934 830658 • Email:
rosapmrichards@gmail.com • Web:
https://www.linkedin.com/in/rosa-richards-7a515936/
IET ANNUAL BUYERS’ GUIDE 2022/23
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96
