Greenhouse Gas Emissions Associated with Tree Pruning Residues of Urban Areas of Northeast Brazil

Abstract

There are environmental concerns (especially regarding climate change) associated with the negative effects of some pruning waste management practices. Converting urban tree waste into valuable products can help mitigate climate change, but it is important to quantify the repercussions of tree waste scenarios in an urban context. The objective of this study was to quantify the greenhouse gas (GHG) emissions for six scenarios of urban pruning waste in urban areas. To this end, the life cycle assessment methodology was applied to real data obtained from five municipalities of the Paraíba state in 2012–2021 (northeast Brazil). The six scenarios were: sanitary landfill (current practice), sanitary landfill with methane capture, municipal incineration, reuse of wood, heat generation and electricity generation. Considering the 10-year period, the sanitary landfill emitted 1048 kt CO2e, and when methane was captured at the landfill, emissions decreased to 1033 kt CO2e. The lowest emissions were associated with electricity generation, with 854 kt CO2e. The municipality of João Pessoa presented the highest emissions, followed by Cabedelo, Santa Rita, Bayeux, and Conde. Transportation was responsible for the highest share of GHG emissions. Disposal of urban pruning waste at the sanitary landfill presented the highest emissions, and it has been demonstrated herein that pruning waste can be used for the production of bioenergy, with significant potential to mitigate GHG emissions at local levels.