Life cycle energy assessment of pneumatic waste collection static systems: A case study of energy balance for decision-making process

Abstract

Waste collection presents a significant influence in the environmental sustainability of municipal solid waste (MSW) management. Conventional door-to-door collection consumes high amounts of fuel for waste transportation, thus generating significant direct greenhouse gas emissions (GHG). Pneumatic collection emerges as an alternative to conventional trucking system, comprised by an underground network of long distance pipelines that carries MSW fractions to a central collection plant where the waste is collected and compacted. Such systems represent a way of arranging waste collection in densely populated urban areas and have recently been used in the design of smart cities to control waste flows. While this technology apparently reduces direct air emissions, suffers from large energy demand derived from vacuum production for waste suction. This work compares both conventional door-to-door and pneumatic collection systems from a life cycle approach, obtaining that the latter accounts for 5 and 3 times more energy demand and CO2-eq. emissions than conventional collection, respectively. Results suggests that the electricity consumption and the origin of electricity have a significant influence on the results, since vacuum production is responsible for more than 99 % of the total impacts for pneumatic scenario, while diesel for trucking accounts to around 70 % of the conventional system impacts. Greener electricity mixes and less energy consuming materials are required in order to ensure the environmental sustainability of pneumatic systems.