Biogas and biomethane station

The biogas plant in Bauska, Latvia will use clean chicken manure with bedding as raw material in volumes that will reach 50,000 tons per year. The final product is biomethane, which will be injected into the common natural gas network (pressure around 17 bar). The project is designed with future expansion options – CO2 for the implementation of collection and liquefaction technologies, as well as for the construction of an additional post-fermentation (storage) tank.

The station project consists of more than 14 different engineering structures and buildings. They include:

• Two receiving tanks with water connection and mechanical stirring, which ensure the supply of homogeneous raw material for the fermentation process. The tanks are equipped with suction equipment and a biological filter for odor and emission treatment with 98% efficiency.
• Four fermentation tanks equipped with mechanical stirrers and a heating circuit for efficient biogas production. The tanks are covered with a double membrane system for gas collection and discharge, a safety relief valve, service platforms and process control sensors. For tank maintenance, the project includes custom-designed doors that also allow access for heavy machinery for more efficient cleaning.
• Biological pre-treatment station for the removal of sulfur and ammonia from biogas.
• External implementation of biomethane production technologies. Biogas is purified to biomethane, which is then fed into the local natural gas network. 
• Two post-fermentation tanks, where the processed raw material, or digestate, is stored. The tanks are equipped with a gas capture system to increase the efficiency of the process. The digestate will be used as a valuable fertilizer product in local agriculture.
• A dual-burner boiler that will allow the production of the heat required for the process from natural gas, produced biogas or biomethane;
• A burning torch for safety.

The plant will process 50,000 tons of chicken manure per year and produce:

• 57 GWh of biomethane;
• 135,000 tons of fertilizer production per year.