”The biogas plant based on dry anaerobic digestion process delivered by BioGTS Ltd has a waste treatment capacity of 19,500 tons annually,” explains Kari Mukala, Project Engineer at the Haminan Energia Ltd., about the biogas plant, which started its operations in Vahterikonkangas in Virolahti in the end of 2015.
”A third of the plant’s feedstock consists of agricultural byproducts, a third of organic waste from industry waste and a third of organic waste from grocery stores and restaurants. Municipal waste is not used, as we wish to maintain an ‘organic status’ for the biogas resulting from the process”, Mukala continues.
Mukala describes the biogas plant as being a big cow.
“From the reception hall the feedstock mixture proceeds to the hygienization unit, where the temperature is raised to 70 degrees. From there the mixture is pumped into three reactors, where the mixers keep it at uniform quality. From start to end, this process takes three weeks, meaning the mixture is moving forward for approximately one meter in a day.”
Fuel for 900 natural gas vehicles annually
Biogas is produced in a period of three weeks in the three reactors of the biogas plant. Biogas is suitable for both transportation use and for electricity and heating.
“The produced biogas is upgraded into biomethane and injected into the company’s own gas grid, where it is mixed with the natural gas provided by Russia. The energy content of the annually produced biogas is 15 to 20 gigawatt-hours; the equivalent of the annual consumption of 1,500-1,800 passenger biogas vehicles,” Kari Mukala explains.
Haminan Energia Ltd believes and invests in the future of biogas vehicles; currently the company has one own refueling station in Hamina.
“We are urgently trying to find a site for another refueling station near the Vaalimaa boarder station. Our goal is, that a major share of the biogas produced at Virolahti is used as vehicle fuel,” says Janne Ristola, Director, Energy Business at Haminan Energia Ltd.
A viable power plant
In addition to biogas, the digestate from the plant can also be used as fertilizer or soil improvement media.
“The technology developed by BioGTS creates a new opportunity for agriculture to exploit the growth potential of the fields. We have already gotten good deals for next year’s fertilizer deliveries. At first fertilizers leave from our plant as dry matter or slurry, but our medium-term goal is to granulate it. Many farmers have also seized the opportunity to produce biogas feedstocks in the protection zones of the fields,” Janne Ristola explains.
“Haminan Energia Ltd has already for years invested in emission-free and renewable energy, and the Virolahti biogas plant is one of these goals,” Haminan Energia representatives Kari Mukala and Janne Ristola state.
”We are very happy with our present cooperation with BioGTS. A continuously operating biogas plant is viable and the treatment capacity is planned to be increased from the current 19,500 tons to 32,500 tons per year,” the men continue.
The Virolahti biogas plant will add two more reactors in addition to the three reactors that are currently operating. The extension is in progress. The plant expansion will be provided by BioGTS Ltd.