Taking Action to Reduce Scope 1 Emissions - Where to Start, Progress & Excel?

Emily Wiszniewski (Jacobs Australia), Aprilia Vellacott (Jacobs, Australia), Amanda Lake (Jacobs, UK), Olivia Millard (Jacobs, Australia), Emma Shen (Jacobs, Canada), Mikkel Holmen Andersen (Unisense A/S, Denmark)

Water Authorities globally, including in New Zealand, are increasingly setting Net Zero greenhouse gas (GHG) emission targets. With the use of renewable energy the reduction in Scope 1 GHG emissions (predominately Nitrous Oxide (N2O) and Methane) is critical to achieving Net Zero GHG emissions without significant off-sets. 

This paper provides:
• An overview of the key sources of N20 and Methane emissions
• Practical approaches to monitoring emissions
• Practical tips for reducing emissions from existing infrastructure
• A case study presenting a semi-quantitative assessment of water and wastewater treatment technologies to review net zero technologies for consideration in plant upgrades and augmentations 

N2O is a potent GHG with global warming potential (GWP) of 265. N2O can be generated during biological nitrogen removal (BNR) processes and emitted from wastewater treatment plants and can contribute up to 75 percent of the GHG footprint of WRRFs, especially in locations where the energy grid is primarily from renewable sources. Methane is a potent GHG with a GWP of 28. Methane is generated in anaerobic conditions and emitted from wastewater treatment plants, particularly from sludge and biosolids treatment processes.

This paper considers impacts on GHG emissions across the whole wastewater treatment site, as well as the impact on site energy demands.

This paper summarises experience in investigating and undertaking leading research into N2O emission monitoring and reductions globally, as well as design of low methane emission sludge treatment processes. This includes an outline to approaches to monitoring N2O and methane emissions, challenges and issues in monitoring and considerations and practical tips for implementing an N2O and Methane emission reduction program. The paper also presents a summary of
successful projects globally which have reported material reductions in N2O and Methane emissions from Water Authorities taking proactive actions to reducing site GHG emissions.

Practical mitigation measures can be effective in minimising fugitive methane emissions at biogas plants. Globally leading case studies from national monitoring programmes and long term methane mitigation schemes in Europe have shown that technical design and operational measures are required to be addressed. Technical measures, including construction of enclosed assets with biogas valorised or flared; (sealing, using best practice in design phase); operational measures include proactive facility management, adoption of leak detection and repair / ‘find and fix’ methods plus third party quantification to show progress year on year in conjunction with (ongoing) measurements and maintenance. In addition, it is likely that indirect measures (knowledge transfer to plant operators) can also develop new approaches and cultures which will support reducing fugitive methane emissions.

The paper reviews approaches to prioritise and act including the recent review of net zero technologies for Ofwat. The review used a semi-quantitative assessment of water and wastewater treatment technologies to assess alignment with net zero targets and make recommendations for focus over the 2025 – 2030 investment period.

Decarbonising in line with national interim and final targets on net zero is not without its challenges, however it also presents significant opportunities for the water sector.