Contribution project

Generating energy from waste water

Bulgaria, Sofia

ClimatePartner ID: 1236

Project details

Gas RecoveryGet to know the project

Sofiyska Voda provides water supply, sewerage and waste water treatment services to over 1.4 million citizens in the Municipality of Sofia. The company operates the Kubratovo waste water treatment plant, processing about 400,000 cubic metres of water per day. The plant is located close to the village of Kubratovo, 20 km outside of Sofia, near the Iskar river.

In order to reduce greenhouse gas emissions the company implemented a system for anaerobic sludge treatment and combustion of biogas for power generation. Methane is captured in common tanks and then supplied to the newly installed combined heat and power (CHP) gas engines for electricity and heat production. This substitutes the plant’s electricity purchases from the grid and also diesel fuel usage. Excess electricity is supplied to the grid. The project reduces the volume of sludge by up to 50 percent. It saves methane emissions from open anaerobic sludge tanks, drying beds and landfill disposal sites and reduces CO₂ emissions from fossil fuel-based energy generation.

70,276 t CO₂Estimated annual emissions reductions

Project Standard

The project contributes to the the United Nations' Sustainable Development Goals

How does gas recovery contribute to climate action?

Methane is a greenhouse gas emitted by many processes including livestock farming, waste management, sewage treatment, oil production, and coal mining. When released into the atmosphere, it oxidises first to carbon monoxide and then to carbon dioxide, making it a major contributor to global warming. Climate projects avoid these emissions by capturing the gas and using it to generate heat or electricity, or by processing the gas into dry and liquid gas. In this way, the gas is not released into the atmosphere and is used to generate energy instead. Gas recovery projects in the ClimatePartner portfolio are registered with international standards.

The project aims to contribute to these United Nations’ Sustainable Development Goals (SDGs).

Project facts

Climate projects generally fall into one of three groups: carbon reduction, carbon removal, or carbon avoidance. Carbon reduction projects reduce the amount of greenhouse gas emissions produced by a specific activity (e.g., improved cookstoves). Carbon removal projects remove carbon from the atmosphere by sequestering it in carbon sinks (e.g., reforestation). Carbon avoidance projects avoid greenhouse gas emissions entering the atmosphere (e.g., protecting forests from deforestation with REDD+ projects).

All climate projects are based on international standards. They set processes and requirements which carbon projects must fulfill to be recognised as a proven method of reducing carbon emissions.

Climate projects demonstrably reduce, remove, or avoid greenhouse gas emissions. This is achieved with various technologies, ranging from nature-based solutions to social impact projects and renewable energies.

Most standards on the voluntary carbon market list their projects in public registries. The registries are used to store project data and track issuances and retirements of verified emission reductions. The registry ID can be used to identify projects in the standard registry.

Check out this project

Climate projects go through third-party validation and verification. Verification happens regularly after each monitoring period. A validation and verification body checks and assesses whether the values and project activities stated in the monitoring report are correct and verifies them. As with validation, visits to the project site are often part of the process.

Climate projects go through third-party validation and verification. Validation happens early in the project life cycle and ensures that the project design is in line with current processes and requirements. This phase often also involves field visits with on-site interviews and analyses. Auditors are accredited, impartial assessors who have to be approved as a validation and verification body (VVB) by the standards body.

This figure shows the estimated annual emission reductions calculated before the project started. The actual number of emissions saved in each monitoring period may differ. The background to this process is that in order to be registered as a climate project, the project operator must submit the calculation of the estimated emissions savings using the ex-ante methodology in a Project Design Document (PDD), which is similar to a business plan. This calculation is validated by an independent auditor. The values determined in the PDD are recalculated during regular monitoring periods based on actual project performance, documented in a monitoring report, and verified again by independent auditors at the end of the monitoring period to ensure a robust process. Independent verification thus provides ex-post verification of actual emission reductions. Verified emission reductions are not distributed until the savings have actually been made.

* For certified projects only: the project-related information on this page is based on the documents in the register.

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