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Weltec Biopower building two dairy biogas plants in Japan

Germany-headed biogas producer and technology supplier Weltec Biopower GmbH (Weltec) has revealed that it is currently building two agricultural 250-kW biogas plants for one of Japan's major milk producers. One of the plants is being set up in Urahoro on Japan's island of Hokkaido. The second plant is being built in Sakata in the prefecture of Yamagato on Honshu, the largest island.

The 250 kW biogas plant in Urahoro, Hokkaido, will go into operation in the summer of 2021 (photo courtesy Weltec).

The structural design of both biogas plants takes the earthquake risk in these regions into consideration. The generated power and heat will be used directly on-site in order to enable energy autonomy.

The commissioning will take place in summer 2021 in Urahoro and in autumn 2021 in Sakata.

Biogas has a good reputation

Following the Fukushima nuclear disaster in March 2011 and thanks to the support of renewable energies, biogas enjoys a good reputation in Japan. 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 boasts plenty of biomass potential.

Efforts to promote biogas projects had already started in 2002 and already a short while thereafter, Weltec built its first “Made in Germany” plant in Japan.

However, the pace of development in anaerobic digestion (AD) picked up only after the government introduced the feed-in tariff (FIT) scheme for green energy in July 2012.

Hybrid dairy farm projects

These most recent biogas projects in Japan for Weltec are on so-called hybrid dairy farms. This means 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 locations of an agricultural company group yield approximately 30 000 tonnes of liquid cattle manure, which will be used for energy production in the AD plants.

Insulated steel tanks

To ensure efficient digestion, the company is setting up one stainless-steel digester in Urahoro. 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 will each have a capacity of 3 176 m3.

According to Weltec, the benefits of stainless-steel tanks include compact shipping in just a few containers from Europe to Japan and easy adaptation to the structural requirements in earthquake regions.

At the Urahoro site on Hokkaido, the liquid substrates will be pumped to 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 set up in Sakata.

Double membrane roof

Due to the cold winters with a lot of snow, the pre-storage 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.

In Sakata on the main island of Honshu, cowsheds are currently being built in addition to the biogas plant. This location should be ready in autumn 2021 (photo courtesy Weltec).

Following the separation, the digestate will be spread on the company’s own fields as fertiliser. Apart from the digesters, upstream and digestate storage tanks, separation and pump technology, Weltec is also setting up a 250-kW biogas-fired cogeneration unit at each of the locations.

Parallel grid pilots

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

According to Weltec, this makes also sense from an economic perspective, as the grid capacity and stability in Japan is endangered especially in the earthquake areas.

The fact that the framework conditions for the development of bioenergy are favourable is a great advantage. Weltec notes that the annual biomass potential in Japan amounts to approximately 284.4 million tonnes, enough to produce about 13 billion kWh of electricity and continually supply 2.8 million households.

The efficient utilisation of raw material in biogas plants such as in Urahoro and Sakata contributes to the economic viability, eco-compatibility and security of supply and thus to the success of the energy transition in Japan.

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