Life-Cycle Energy Use and Greenhouse Gas Emissions Inventory for Water Treatment Systems

Abstract

Given the rising concerns over scarce energy resources and global climate change, life-cycle inventories focusing on energy use and greenhouse gas ͑GHG͒ emissions were developed for the City of Toronto municipal water treatment system ͑WTS͒. Three processes within the facility use phase of the life cycle were considered: Chemical production, transportation of materials, and water treatment plant operation. The impacts of chemical manufacturing were estimated using the economic input-output life-cycle assessment model, while the inventories for transportation and operational environmental effects were based on data from the GHGenius model and regionally averaged data. Operational burdens, 60% of which are attributed to on-site pumping, accounted for 94% of total energy use and 90% of GHG emissions. By contrast, transportation-related energy use and emissions were deemed insignificant. The normalized energy use of the studied WTS was found to be between 2.3 and 2.5 MJ/ m 3 of water treated. Water conservation practices are recommended as abatement strategies for the energy use and GHG emissions associated with water treatment. The limitations and uncertainties introduced by selected model parameters and through combining various estimation methodologies are discussed, as is the model's relevance.

Improving the carbon footprint of water treatment with renewable energy: a Western Australian case study

“…This finding is similar to Racoviceanu et al (2007) as the water treatment facilities phase has contributed the most GHG emission which is 0.12 kg CO 2 -eq per m 3 whereas the total GHG emission from the total energy use for a water treatment system is 0.13 g CO 2 -eq per m …”

“…A similar study carried out by Mrayed and Leslie (2009) found that the greenhouse gas emissions from the generation of electricity for the operation of seawater desalination plant accounted for a large proportion (95 %) of the total greenhouse gas emissions, followed by chemicals production (4 %). Also a North American study found that 90 % of the GHG emissions came from electricity generation and the rest from chemicals (Racoviceanu et al 2007). …”

“…Life cycle assessment has widely been used to assess GHG emissions and other associated environmental impacts for water supply and wastewater treatment options in Australia and elsewhere in the world (Barber 2008;Coday et al 2015;de Haas et al 2009;Foley et al 2007;Foley et al 2010;Hall et al 2011;Raluy et al 2005;Stokes and Horvath 2006;Lane et al 2010;Lundie et al 2004;Racoviceanu et al 2007;Shahabi et al 2015a;Yoshida et al 2013). None of them have calculated the net GHG emissions from all existing and alternative water supply options in Western Australia.…”

“…The available published literature have shown that the use of fossil energy contributed significant portion (>90 %) of the total GHG emissions from the water treatment process (Racoviceanu et al 2007;Biswas 2009). However, the replacement of fossil energy with renewable energy could reduce the GHG emissions significantly by more than 90 %.…”

Suitability of combined sewers for the installation of heat exchangers

“…According to the articles [1,2] in big cities between 7 and 10% of total energy spent in the whole UWC is lost in the sewer systems and the primary energy consumption for collection and transportation of wastewater and other water equals 105 MJ/cap/year in the Netherlands, 530 MJ/cap/year in USA, 380 MJ/cap/year in Toronto and 74 MJ/cap/year in Sydney. A lot of this energy is in form of heat from water heating in households and from industrial processes [2][3][4].…”