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ARTICLE Quantiﬁcation and comparison of carbon emissions for ﬂexible undergroun

ARTICLE Quantiﬁcation and comparison of carbon emissions for ﬂexible underground pipelines Lutfor Rahman Khan and Kong Fah Tee Abstract: The life cycle assessment of underground gravity and pressured pipeline networks are studied to quantitatively calculate the carbon dioxide (CO2) emissions. The life cycle of a pipeline can be classiﬁed into four phases that are fabrication, transportation, installation, and operation. Three typical ﬂexible underground pipe materials, namely, steel, ductile iron (DI), and polyvinyl chloride (PVC) have been considered. The most dominant phase of the life cycle is pipe manufacturing and fabrication process, resulting in large amounts of CO2 emissions. The results indicate that PVC provides the best environmental savings compared to steel and DI pipes in terms of CO2 emission and emission mitigation cost. This methodology in estimating life cycle carbon footprint and cost could be used as managerial decision support tool for management of any underground pipeline networks. Key words: carbon footprint, buried pipelines, carbon pricing, energy consumption, embodied carbon. Résumé : Dans le présent article, on étudie et évalue le cycle de vie de réseaux de conduites souterraines libres ou sous pression aﬁn de calculer les émissions de dioxyde de carbone (CO2). Le cycle de vie d’une conduite peut être divisé en quatre phases, soit la fabrication, le transport, l’installation et la mise en service. On s’est intéressé a ` trois matériaux qui composent habituellement les conduites souterraines ﬂexibles : l’acier, la fonte ductile (FD) et le polychlorure de vinyle (PVC). La phase la plus importante du cycle de vie est la fabrication ou la production, dont le procédé entraîne l’émission de grandes quantités de CO2. Les résultats montrent que le PVC est le matériau le plus écologique, en termes d’émissions de CO2 et de coût de réduction des émissions, si on le compare a ` l’acier et a ` la fonte ductile. Cette méthode d’évaluation de l’empreinte carbone et du coût du carbone tout au long du cycle de vie des conduites pourrait servir d’outil d’aide a ` la décision aux personnes responsables de la gestion de n’importe quel réseau de conduites souterraines. [Traduit par la Rédaction] Mots-clés : empreinte carbone, conduites souterraines, détermination du coût du carbone, consommation d’énergie, carbone intrinsèque. 1. Introduction The term carbon footprint is commonly used to describe the total amount of carbon dioxide (CO2) and other greenhouse gas emissions in a year caused by an organization, event or product. Carbon footprint analysis is becoming more and more popular in every industry due to increasing concerns on global warming and greenhouse gases emissions. Carbon dioxide is the main contrib- uting factor and other greenhouse gases, such as methane, ni- trous oxide etc. are insigniﬁcant. To identify and mitigate this hazard, it is critical to precisely estimate carbon footprints for an engineering project in the initial planning stage. Therefore, it is important to follow a structured methodology and to classify all the possible sources of emissions thoroughly. Like other engineer- ing projects, it is required to identify potential beneﬁts of carbon footprint analysis of underground pipelines and to enforce it as a mandatory practice for waste and water industry. The methodol- ogy in estimating life cycle carbon footprint and cost could be used as managerial decision support tool for management of any underground pipeline networks (McDonald and Zhao 2001; Tee and Li 2011; Khan et al. 2013; Tee et al. 2014a). A major portion of the underground water and wastewater in- frastructure in Europe is rapidly approaching the end of its useful service life and therefore, large-scale construction works will need to be undertaken for rehabilitating or renewing these vital infrastructure assets. In the past, various researchers and organi- zations recognized the importance and the applicability of prob- abilistic approach in the reliability estimation of buried pipeline systems (Alani et al. 2014; Chughtai and Zayed 2008; Babu and Srivastava 2010; Piratla et al. 2012; Tee and Khan 2012, 2014; Tee et al. 2013, 2014b, 2015). On the other hand, to mitigate CO2 emis- sions, huge investment will also be needed for the future world. For example, the capital needed for buried infrastructure in the United States from 2000 to 2019 is approximately $274 billion (EPA 2002). Many countries including the UK, are trying to minimize energy consumption and reduce emissions to moving toward sus- tainable development. Therefore, it is essential to monitor the environmental impacts on all underground pipeline infrastruc- ture projects and minimize them whenever possible. Normally, underground infrastructures are installed using ei- ther open cut (cut and cover) or trenchless (cured in place pipe, pipe jacking, pipe bursting, etc.). Open cut construction requires a trench to be excavated to the required depth and width along the entire length of pipeline. On the other hand, trenchless construc- tion methods typically require only minimal excavation (entrance and (or) exit pits) or no excavation. According to Adedapo (2012), deﬂections in trenchless pipes are approximately one-quarter smaller than those induced during open cut-and-cover installa- tion. Moreover, it is possible to defuse environmental and other constraints at an early stage by applying trenchless installation Received 31 March 2015. Accepted 3 July 2015. L.R. Khan. Faculty of Engineering and Science, University of Greenwich, UK; Rail and Ground Engineering, Jacobs Engineering Ltd, Wokingham, UK. K.F. Tee. Faculty of Engineering and Science, University of Greenwich, UK. Corresponding author: Kong Fah Tee (e-mail: K.F.Tee@gre.ac.uk). 728 Can. J. Civ. Eng. 42: 728–736 (2015) dx.doi.org/10.1139/cjce-2015-0156 Published at www.nrcresearchpress.com/cjce on 9 July 2015. Can. J. Civ. Eng. Downloaded from www.nrcresearchpress.com by TUFTS UNIV LIBRARY on 02/20/18 For personal use only. method. Furthermore, the cost for trenchless technique is below the cost for open trench method. However, open cut may appear economical in terms of direct cost but it has high social and envi- ronmental costs, such as carbon and greenhouse gas emissions when the construction work is executed in densely populated urban areas (Rehan and Knight 2007). The life cycle assessment (LCA) has been applied in evaluating environmental effects to assess the environmental performances. The life cycle activities include extraction of raw materials, man- ufacturing the pipe used in the project, transportation of pipe to construction site, laying the pipe in the trench, operation and maintenance, dismantling and disposal or recycling the pipe. There are several LCA studies in the wastewater and drinking water infrastructure systems which have been found in literature. Emmerson et al. (1995) used the LCA to evaluate the environmen- tal effects of small-scale sewage treatment works. Zhang and Wilson (2000) performed an LCA analysis for a large sewage treat- ment plant in Southeast Asia and reinforced the results by Emmerson et al. (1995). Skipworth et al. (2002) investigated the entire life cycle costs for water distribution systems in the UK. Vidal et al. (2002) also used LCA for understanding the environ- mental consequences for wastewater treatment plant. Filion et al. (2004) developed a LCA model to quantify the energy consump- tion of a water distribution system in New York tunnels and to compare life cycle energy for different pipe replacement sched- ules. Their research revealed that the used energy was the primary contributor to environmental burdens and the operational stage of the technologies had the highest share of environmental ef- fects. Besides that, Dandy et al. (2006) developed a water distribution system optimization program that incorporates the sustainability objectives of life cycle costs, energy use, greenhouse gas emis- sions, and resource consumption. Wu et al. (2010) developed a multi-objective optimization procedure to design water distribu- tion systems that minimize the costs and greenhouse gas emis- sions. Venkatesh et al. (2009) studied the contribution of different stages in the life cycle of wastewater pipelines to greenhouse gas emissions. These studies also concluded that energy (i.e., fuel) was an important factor in LCA in the total environmental impacts associated with the plants, where the sewer pipes were made from reinforced concrete, steel, polyvinyl chloride (PVC), cast iron, and ductile iron (DI); and water distribution pipes were manufactured from steel and ductile irons. A limitation is that these studies did not consider the installation and transportation phase when esti- mating CO2 emissions. Recio et al. (2005) also quantiﬁed CO2 life cycle emissions of a pipeline project in Spain through a case study. However, the installation and break repair phases of the pipeline life cycle were not addressed in the analysis. In integrated pipeline (IPL) project (Chilana 2011), carbon footprint analysis was per- formed to compare steel and prestressed concrete cylinder pipe (PCCP), which is a joint effort between the Tarrant Regional Water District and the City of Dallas. Fuel consumption by construction equipment for installation of pipe in the trench was found to be similar for both steel pipe and PCCP, but PCCP was found to have smaller carbon footprint due to less CO2 emissions in the environ- ment. To overcome the above limitations and to ﬁll the research gaps, this paper demonstrates a model for assessing, quantifying and comparing life cycle energy consumption and respective CO2 emissions as well as predicting the associated cost values for both gravity and pressured pipelines with uploads/Ingenierie_Lourd/ khan.pdf