A 5 MW combined heat and power plant and biogas purification unit for a wastewater treatment facility

This project is a great example of how energy independence, environmental responsibility, and efficiency can come together in a single solution! AS Tallinna Vesi’s goal is to reduce electricity consumption at its wastewater treatment plant and increase the facility’s energy self-sufficiency. Previously, the potential of the biogas generated from sewage sludge was not fully utilized. As a responsible company, Tallinna Vesi aims to reduce its environmental impact, meet the EU’s renewable energy targets, and improve overall energy efficiency.

FILTER designed, built, and installed the new 5 MW combined heat and power (CHP) plant at the Paljassaare site, enabling much more efficient use of biogas. The plant features 2.1 MW of electricity generation and up to 2.2 MW of heat generation capacity. The system includes a biogas purification unit, two INNIO Jenbacher gas engines, and a heat exchange hub (oil heat exchanger, cooling water heat exchanger, flue gas heat exchanger, and intake air heat exchanger). A new biogas pipeline was constructed to supply the CHP plant, equipped with flow meters, drying, compression, and purification units. Purified biogas can also be directed to existing gas boilers in the boiler house, increasing both system flexibility and overall efficiency. FILTER’s team is responsible for preventive maintenance of the plant to ensure smooth and reliable operation.

According to Aleksandr Timofejev, CEO of Tallinna Vesi, the new CHP plant built on the grounds of the Paljassaare wastewater treatment plant allows the company to produce energy in an environmentally friendly way by converting sewage sludge—a by-product of wastewater treatment—into biogas.

“Our test period, which began last year, confirmed that biogas generated from sewage sludge can be successfully used to produce energy for our own needs, helping to keep operating costs under control. During the test phase, we produced nearly 12,000 MWh of heat and 8,100 MWh of electricity annually. This fully covers the heat demand and nearly half of the electricity demand of the Paljassaare plant,” explained Timofejev.

Biogas production is still being further developed, as the full capacity of the CHP plant has not yet been reached. The amount of energy generated annually would be enough to cover the electricity needs of approximately 3,800 average households. “The successful completion of the test phase and the launch of the plant mark a significant milestone in our sustainability journey,” said Timofejev. “It’s a practical example of circular economy principles in action.”