Biogas power in Japan and Finland

Image: This Weltec Biopower supplied 250 kW biogas plant in Urahoro, Hokkaido, Japan, is due to enter operation in the summer of 2021

The Japanese plants are being supplied to one of Japan‘s major milk producers. One of the plants is located in Urahoro, Hokkaido, and the other is being built in Sakata, Honshu.

The structural design of the two biogas plants takes the earthquake risk in these regions into consideration, notes Weltec. The power and heat will be used directly on the respective sites to achieve grid independence. Commissioning is expected to take place in summer 2021 in Urahoro and in autumn 2021 in Sakata.

Following the Fukushima nuclear disaster in March 2011 and thanks to the support provided to renewables, biogas enjoys a good reputation in Japan, according to Weltec Biopower.

Among the renewable energy sources, “biogas is considered to be a weather-independent energy source that makes a significant contribution to grid stability”, the company says.

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 started back in 2002, Weltec observes, and a “short while thereafter, it built its first ‘Made in Germany’ plant in Japan.” However, the pace of development in Japan picked up only after the government introduced the feed-in tariff for green energy in July 2012.

These latest biogas projects in Japan are located on “hybrid” dairy farms, where 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 yield about 30 000 t of liquid cattle manure, which will be used for the energy production in the anaerobic digestion plants. To ensure efficient digestion, Weltec is setting up one stainless steel digester in Urahoro, while in Sakata, the company 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. 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.

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.

As well as the digesters, upstream and digestate storage tanks, and separation and pump technology, Weltec Biopower is providing a 250 kW CHP unit at each location. The power will not be fed into the grid, as already noted, but will be used to power the milking parlour and other farm facilities.

This “makes sense from an economic perspective” says Weltec Biopower, as grid capacity and stability are issues in Japan, especially in earthquake areas.

Black gold in Turku

The recently commissioned Turku plant is owned by a group of pig farmers and runs entirely on liquid manure. It has been built in co-operation with Weltec Biopower’s long-standing Finnish partner Doranova.

The orientation of environmental policy in Finland is increasingly towards sustainable nutrient recycling, says Weltec, noting that “while in other parts of the world manure and slurry are seen as waste, the Finns exploit the advantages of the so-called black gold.” Fertilisation with this organic substance improves the structure of the soil and increases the carbon storage in the ground, while an upstream biogas process delivers climate-neutral energy.

According to Weltec Biopwer, “both the farm structure and the location of the Finnish pig farmers presented an ideal setting for the new anaerobic digestion project”, with some 40 000 t/y of pig manure being available as input material for the stainless-steel digester.

Image: Weltec Biopower recently commissioned this 250 kW biogas plant near Turku in southwestern Finland. This plant, owned by a group of pig farmers, runs entirely on liquid manure

The heat generated by the 250 kW CHP unit is used to preheat the liquid manure, which is first buffered in an upstream slurry pit. To minimise the loss of heat in the harsh Finnish winter, Weltec equipped the digester cladding with an extra-thick insulation layer, resulting in a more efficient digestion process.

By 2025, 50% of Finland’s approximately 17.3 million t/y of animal dung is to be processed, for energy production and fertiliser. “Such efficient nutrient recycling effectively prevents the eutrophication of the water system and eliminates the need for elaborately produced artificial fertiliser“, says Mikko Saalasti, head of the biogas department of Doranova. According to Saalasti, “making use of nutrients from the black gold” represents a key step towards improving Finland’s water supply systems, with the production of green power an added benefit.