Converting Sewage Gas to Energy in Wastewater Treatment Plants
GE Power &
Water’s Jenbacher gas engines provide the solution to the rising
energy costs that wastewater treatment plant (WWTP) operators have had to pay
to meet their discharge permit requirements. Our gas engines efficiently and
reliably convert sewage gas into electricity in plants that use anaerobic
digestion for biosolids treatment. The process covers up to 80% of a
plant’s electricity needs and makes it unnecessary to burn fossil fuels for
How It Works
The gas produced in anaerobic digesters from municipal WWTPs generally contains 55 to 65% methane and typically has a low heating value of 500 to 600 BTU/SCF.
Impressive Potential and Results
1. On average, about 1 MW of electricity can be generated from biosolids for every 25-30 MGD of treated wastewater. Several active installations fueled by sewage gas show the generation potential of the GE solution.
2. In Tirol, Austria, two Jenbacher gas engines, a J208 and a J312, power and heat a facility that provides 120% of its energy demand and sends the excess power to the local grid.
3. Two J316 engines provide 1.7 MW of renewable energy for a facility in Portland, Oregon. The electrical output meets about 40% of the plant’s electricity demand.
4. A cogeneration plant in Spain uses three Jenbacher J620 gas engines to produce 8 MW of power – more than four times the norm for a standard biogas plant.
5. Three more J620 units enable a plant in Santiago Basin, Chile, to produce up to 60% of its power with renewable electricity.
Features and Benefits
- LEANOX controls with turbo charger bypass help ensure the correct air-to-gas ratio to lessen exhaust gas emissions while maintaining stable engine operation.
- Electrical efficiency of up to 43% reduces the need to purchase energy from the public grid.
- A fully developed monitoring function, including remote monitoring, creates high levels of reliability.
- Maintenance intervals – 60,000 operating hours for major overhauls and 30,000 for cylinder heads – cut maintenance costs.
- Seamless dual fuel mixing evens out gas production fluctuations by supplementing natural gas as needed.
- High power engine density reduces space requirements and installation costs.
- The low-vibration engine has negligible impact on buildings.