SUTAS KARACABEY BIOGAS PLANT

Audit Analysis

The SUTAS Karacabey Biogas Plant is a Gold Standard small-scale biogas project with VVB-confirmed additionality and no reversal events, but it carries significant data-quality concerns: a three-to-six digester discrepancy between the PDD and site, multiple outstanding corrective actions, a project-specific modeled baseline, zero leakage deduction, and a 2.5× year-on-year ERR jump linked to a capacity extension. The project is functional but its credit claims rest on a baseline and monitoring framework that has not been fully reconciled across documents.

Project Description

Red Flags

• ⚠Discrepancy in anaerobic digester count: 3 stated in the PDD versus 6 observed on site (CAR02 in the 2025 verification report), raising questions about the accuracy of the project design and the ex-ante ERR estimate.
• ⚠ERR jumped from 64,093 tCO₂e (2023 verification report) to 161,394 tCO₂e (2024 monitoring/verification reports), a 2.5× increase attributed to a capacity extension, but the justification and updated ex-ante estimate are not clearly documented.
• ⚠FPIC was not conducted despite the project involving local manure-supply farms, and multiple corrective actions (equipment details, calibration records, baseline scenario for new farms) remain outstanding as of the September 2025 verification report.
• ⚠Zero leakage deduction is justified as 'quantified' in the 2025 verification report but was originally described as 'deemed negligible' in the 2014 PDD; the quantification methodology and results are not transparently presented.

Credit Vintages