The potential for biogas production from autumn tree leaves to supply energy and reduce greenhouse gas emissions – A case study from the city of Berlin

https://doi.org/10.1016/j.resconrec.2022.106598Get rights and content
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Abstract

Autumn tree leaves are residues that are generated annually and usually composted, but can also be used as a feedstock for biogas production. In this study, three scenarios were analysed to evaluate the utilization of tree leaves from the city of Berlin in Germany: a) composting (business-as-usual scenario); b) biogas production; and c) the pretreatment of leaves before biogas production. For these scenarios, greenhouse gas emissions and energy production potential were calculated using the biological resource utilization impacts (BIORIM) model and considering the location and capacity of existing agricultural biogas plants. A special focus was set on the decay of leaves before their entry into the biogas plant. The overall comparison showed that the biogas-related scenarios had a better performance in terms of greenhouse gas emissions (-140.1 kg of CO2eq per tonne of leaves for biogas and -167.4 kg of CO2eq for pretreatment before biogas) than the business-as-usual scenario (49.0 kg of CO2eq for composting). The pretreated leaves resulted in the lowest net emissions and highest energy production per tonne of feedstock. Measures to reduce the decay of leaves, such as increasing the loading to the biogas plant or ensiling, resulted in lower net emissions and higher energy output. However, further research is needed regarding costs and logistical feasibility for proper implementation. Using tree leaves for biogas production would represent an alternative energy source, which could reduce the share of fossil fuels and electricity imports for the city of Berlin, where about 7.5 metric ton of pretreated leaves would meet the average electrical energy consumption of one person in one year.

Keywords

Autumn tree leaves
Biogas production
Composting
Tree leaves’ decay
Greenhouse gas emissions
Life cycle assessment

Data Availability

  • The link to the code is shared within the manuscript and in the Attach Files section

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