Energy from Landfill gas
During 2011-12 an energy project on utilization of landfill gas to produce energy was carried out in Kouvola waste facility which is still in use. The project was started by investigating the landfill gas utilization alternatives in cooperation by Kymenlaakson Jäte Oy, the owner of the landfill and CTS Engtec, engineering and consulting company.
Landfill gas can be used to produce power and heat, reducing greenhouse emissions along with renewable energy production. If the landfill gas quality and quantity, as well as local conditions allow, it is possible to upgrade the landfill gas to the natural gas quality. Upgraded gas can be injected to the natural gas grid and used as transportation fuel, for instance.
CTS Engtec carrying out conceptual study
In the project CTS Engtec carried out investment calculations on the conceptual study level, as well as profitability comparison between different landfill gas utilization alternatives. Based on the study the so-called “combined cycle plant” was built at Kymenlaakson Jäte Oy’s landfill. The plant equipment pumps the gas from the landfill extraction wells to the microturbines where it is burnt to produce electricity and heat.
The combined cycle plant’s max. electrical power output is 195 kW, and it can be further increased if there is more gas from the landfill available. From the plant’s exhaust gas heat exchanger 350 kW of heat can be received for further use.
In the modernization of the heating system of the building located at the territory of the waste facility, as well as the drying shed’s detailed engineering CTS Engtec’s scope included HVAC, automation and electrical design.
Landfill gas is generated through the degradation of the waste by bacteria. The main process components are methane and carbon dioxide. Methane is a strong greenhouse gas which legislation determines has to be burnt to reduce emissions. The burning of methane is usually done in a flare. However, methane contains considerable amount of energy creating better utilization options than flaring off.
Before being burnt in microturbines the gas is filtered from impurities. Power produced with microturbines is then used by the waste facility for its own needs, and the rest is sold to the local network company. Part of the heat produced with microturbines is used in heating system of the building situated on the territory of the waste facility, as well as at the newly built drying shed where various wood materials or sludge can be dried.