Weltec Biopower to build two agricultural biogas plants in Japan

Weltec Biopower is building two agricultural biogas plants for one of Japan’s major milk producers.

One of the two 250 kW plants is being set up in Urahoro on the Japanese island of Hokkaido; the second is being built in Sakata in the country’s Yamagato prefecture, on the island of Honshu.

Biogas enjoys a good reputation in Japan, according to Weltec. Among the renewable energies, biogas is considered to be a weather-independent energy source that makes a significant contribution to the required grid stability. Additionally, the preconditions for the development of biogas are ‘favourable’, since, despite the limited availability of other raw materials, Japan has plenty of biomass potential.

Japan’s annual biomass potential amounts to around 284.4 million tonnes, enough to produce 13 billion kWh of electricity and continually supply 2.8 million households.

Weltec’s latest biogas projects in Japan are hybrid dairy farms, meaning that the embryos of special beef cattle breeds are transferred to dairy cows, allowing the farm to produce both milk and beef. Every year, the two farms produce around 30,000 tonnes of liquid cattle manure, which will be used to produce biogas via anaerobic digestion.

Weltec will set up one stainless-steel digester in Urahoro while in Sakata it is building two digesters, as the animal headcount will soon be increased. With a height of 6.3 m and a diameter of 25.34 m, the three bioreactors (in total) will each have a capacity of 3,176 m³. The benefits of stainless-steel tanks, said Weltec, include compact shipping in just a few containers from Europe to Japan, and easy adaptation to the structural requirements in earthquake-prone regions.

At the Urahoro site, the liquid substrates will be pumped into the digester from three upstream storage tanks. Two of the three pre-storages are already in place but are being furnished with state-of-the-art technology. Weltec is building the third pre-storage tank with a capacity of 393 m³, from scratch. Its height is 5.03 m and its diameter measures 9.98 m.

A pre-storage of the same size is also being built in Sakata. Due to the area’s cold winters, the tanks at the two locations will be insulated and furnished with gas-tight double membrane roofs. Additionally, Weltec is setting up a digestate storage tank with a capacity of 524 m³ for each location.

Following the separation, the digestate will be spread on the company’s fields as fertiliser. Aside from the digester storage tanks, separation and pump technology, Weltec is also setting up a 250 kW CHP unit at each of the locations.

Based on the customer’s specification, the plants will run in parallel grid operation. Therefore, both construction projects are viewed as pilot projects in Japan. The power will not be fed into the grid but will be used for the rotary milking parlour and other facilities, which will make the operator more independent from the power grid.

Commissioning will take place this summer in Urahoro and autumn in Sakata.