Approaches to reduce GHG emissions from WASH servicesMay 2023
The present decade has been considered the "critical decade" for climate action. The period from 2015-2021 is the hottest period in past many decades. Temperatures are rising faster than predicted, according to the Intergovernmental Panel on Climate Change (IPCC). The Paris Agreement, which was signed in 2015, set a goal for the global population to stay below 2°C. Although the nations revised or submitted their NDCs before to COP 26 in Glasgow in November 2021.
While IPCC (Intergovernmental Panel on Climate Change) and other estimates focus greatly on direct emissions from the solid waste sector, there are studies that argue higher estimates from the wastewater sector. Additionally, for providing WASH services, a high amount of indirect (scope 2) emissions are generated by using electricity in pumping and treatment operations. Cities are knowns to spend up to 40- 50% of their total revenue expenditure. Thus, a focus on urban WASH services has co-benefits for the functioning of urban local bodies.
The study expands on emissions, factors, scenarios affecting the emissions from components of the services chains of water and sanitation. Firstly, to assess the sources and types of emissions from all the components, a secondary desk review was done in this study, after which for further analysis a case city was selected. As, both direct and indirect GHG emission is associated with water and sanitation, the assessment investigates both the emissions from the service chain. To study all possible carbon pathways, Ichalkaranji was chosen which has both onsite and offsite sanitation systems. The water flow diagram of Ichalkaranji was established to understand the quantity of abstraction of water, treatment, distribution, wastewater generation, treatment, and disposal. The calculations of both direct and indirect emission are based on the guidelines given by IPCC.
The total emissions from these services are to the tune of 31,088 tCO2eq. The split of direct and indirect emissions is 64% and 35% respectively. It was observed that direct emissions from onsite sanitation are very high. However, the abstraction of raw water from a distant source (Panchganga and Krishna River) through pumping has the highest energy consumption.
A few proposals are considered to reduce these emissions and move towards “Carbon neutral WASH services”. The first option considers replacement of old pumping machinery with efficient solar pumps, solar powered treatment plants and electric vehicles to reduce fossil-based energy consumption. Options like scheduled desludging, methane capture unit, capacity enhancement of STP are considered to mitigate direct GHG emissions. Reusing treated wastewater is other option to reduce indirect GHG emission by reducing the water demand.