Costs and benefits of biogas recovery from communal anaerobic digesters treating domestic wastewater: Evidence from peri-urban Zambia. (15th March 2018)

• Record Type: Journal Article
• Authors: Laramee, Jeannette; Tilmans, Sebastien; Davis, Jennifer
• Is Part Of: Journal of environmental management. Volume 210(2018)
• Page Start: 23
• Page End: 35
• Publication Date: 2018-03-15
• Subjects: Biogas -- Sanitation -- Energy recovery -- Greenhouse gas emissions -- Zambia -- Africa; AD Anaerobic digester -- CapEx Capital expenditure -- CH4 Methane -- COD Chemical oxygen demand -- CO2 Carbon dioxide -- CO2e Carbon dioxide equivalent -- GHG Greenhouse gas -- FIB Fecal indicator bacteria -- MJ Mega Joule -- MPN Most probable number -- N2 Nitrogen -- NPV Net present value -- OpEx Operational expenditure -- PT Public toilet -- ST Septic tank -- SSA Sub-Saharan Africa -- SCC Social cost of carbon; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2017.12.064
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Communal anaerobic digesters (ADs) have been promoted as a waste-to-energy strategy that can provide sanitation and clean energy co-benefits. However, little empirical evidence is available regarding the performance of such systems in field conditions. This study assesses the wastewater treatment efficiency, energy production, greenhouse gas (GHG) emissions, and financial costs and benefits of communal ADs used for domestic wastewater treatment in Zambia. Primary data on the technical performance of 15 ADs were collected over a 6-month period and in-person interviews were conducted with heads of 120 households. Findings from this study suggest that ADs offer comparable wastewater treatment efficiencies and greater GHG emission reduction benefits relative to conventional septic tanks (STs), with the greatest benefits in settings with reliable access to water, use of low efficiency solid fuels and with sufficient demand for biogas in proximity to supply. However, absent a mechanism to monetize additional benefits from biogas recovery, ADs in this context will not be a financially attractive investment relative to STs. Our financial analysis suggests that, under the conditions in this study, a carbon price of US$9 to $28 per tCO2 e is necessary for positive investment in ADs relative to STs. Findings from this study contribute empirical evidence on ADs as a sanitation and clean energy strategy, identify conditions under which the greatest benefits are likely to accrue and inform international climate efforts on the carbon price required to attract investment in emissions reduction projects such as ADs. Graphical abstract: Image 1 Highlights: 15 communal anaerobic digesters in Zambia were monitored over a 6-month period. The mean reduction in chemical oxygen demand (COD) ranged from 61 to 83%. Biogas supply was associated with significantly lower charcoal and electricity use. Averted CO2 e emissions amount to 4–13% of per-capita emissions in Zambia. The carbon price required for positive investment ranged from US $9–28 per tCO2 e.