How waste processing and biomass power generation combine to help protect the environment and drive sustainable growth

[Publisher] ORIX Group


Waste has a significant impact on the global environment. The majority of waste processing facilities in Japan incinerate waste; however, as the focus on sustainability grows even more around the world, a new trend of reusing combustible waste as energy is emerging. ORIX Environmental Resources Management is involved in the use of biomass to generate renewable energy. What can we learn about the future of waste processing from the company’s Yorii Biogas Plant in Saitama, Japan?

Extracting value from waste—what is dry methane fermentation?

ORIX Environmental Resources Management is a waste processing business, and since 2006, it has operated one of Japan’s largest private incineration and melting waste processing facilities at Sainokuni Resource Circulation Plant in Yorii, Saitama Prefecture. The facility processes industrial waste produced by plants and general waste produced by households, and recycles it into slag for asphalt, and industrial salt for melting snow.

In June 2021, ORIX completed construction of Yorii Biogas Plant, a next-generation renewable energy power generation facility fueled by biomass; it is one of the largest dry methane fermentation biogas power generation facilities to use general waste in Japan. General waste such as food and paper waste is fermented using bacteria to generate biogas, which is then used to fuel power generation; thus, helping to reduce CO2 emissions.
There are two types of methane fermentation technologies: “wet” and “dry.” Wet methane fermentation is suited to processing liquid or semi-liquid biomass, such as sewage sludge and livestock excrement; however, it is not suited to low-moisture biomass. In contrast, dry methane fermentation is capable of fermenting organic matter with low moisture content, and therefore expands the scope of what can be recycled as biomass. It can even ferment food waste that contains non-fermentable waste such as plastics and, for this reason, it eliminates the effort and costs required for waste separation.

Yorii Biogas Plant

What, then, are the differences between “wet” and “dry” methane fermentation? In wet methane fermentation, semi-liquid livestock excrement is fermented inside a fermentation tank to create methane gas; energy is generated through incineration, or through the driving of a turbine. Since methane gas can be combusted to create both electricity and heat, it contributes to CO2 reductions.

Waste is collected and stored in a “pit”

Yorii Biogas Plant uses dry methane fermentation. This method is capable of fermenting organic matter with low moisture content, and so increases the scope of what can be recycled. In contrast to wet methane fermentation, dry methane fermentation has the added advantage of producing almost no digestive fluids. Some regions have been unable to adopt wet methane fermentation technologies as they lack the ability to discharge treated water; dry methane fermentation makes it possible for such regions to effectively use biomass while still maintaining the quality of nearby water.

Yorii Gas Plant operational flowchart

There are approximately 2,000 waste processing facilities in Japan but, as Masato Kameoka, General Manager of ORIX Environmental Resources Management’s Biogas Business Department tells us, only a handful utilize methane fermentation.

Masato Kameoka, General Manager, Biogas Business Department, ORIX Environmental Resources Management

“In Japan, there are about 30 methane fermentation facilities designed to use household waste—but there are only two private dry methane fermentation facilities in operation. In fact, Yorii Biogas Plant is the first dry methane fermentation biogas power generation facility to be built in the Kanto region in Eastern Japan. The plant is expected to generate approximately 9.8 million kWh of electricity per year, which is roughly equivalent to the annual power consumption of 3,140 households. Through innovations in waste processing, the methane fermentation biogas business is helping to extract value from waste as a resource.”

ORIX: a pioneer in building a recycling-oriented society

ORIX was established in 1964 as a leasing company. After a lease has concluded, the generated waste must be properly processed. Although ORIX initially outsourced the proper processing of waste from its properties, it came to recognize the necessity of processing waste itself. Shigekazu Hanai, President of ORIX Environmental Resources Management, recounts the state of affairs in 2006.

Shigekazu Hanai, President, ORIX Environmental Resources Management

“Around that time, dioxins were under the spotlight; awareness of global warming had also increased over the previous few years. At ORIX, we entered into discussions with Saitama Prefecture regarding new processing methods that might benefit society. We agreed to commence a biogas power generation business that used dry methane fermentation on unused Prefecture-owned land.”

Before the Great East Japan Earthquake in 2011, the prevailing view was that waste should be burned. But times changed, and the idea of using renewable energies began to take hold; this led to demand for processing methods other than combustion. Yet numerous hurdles had to be overcome before Yorii Biogas Plant came into existence.

“At that time,” Hanai continued, “there were no privately-operated dry methane fermentation processing facilities anywhere in Japan. At ORIX, we set ourselves the twin goals of doing things that had not yet been done by other companies, and of benefiting society. We faced great difficulties with laws and regulations, wastewater processing, and eliciting understanding from local residents. Fortunately, however, over the last 10 to 20 years—in part due to our past performance in the region and constructive communication with local communities—we have somehow managed to advance the project.”

A biogas power generator

Renewable energy generated using biomass serves to reduce greenhouse gases that contribute to global warming. As the world shifts toward sustainability, more and more companies are engaging in decarbonization and seeking to achieve carbon neutrality. But why does ORIX Environmental Resources Management choose to involve itself in this business?

“Biomass power generation contributes to the decarbonization of society,” explains Kameoka. “And, by using waste as a resource, it also helps realize a recycling-oriented society. Waste processing is an indispensable part of human life—and I find making this process greener to be extremely rewarding. ORIX operates various different businesses, and its workforce is full of employees who wish to contribute to society through the company’s activities. Indeed, to my mind, ORIX is an aggregation of such people.”


New choices for waste processing facilities

Yorii Biogas Plant is scheduled to commence operating in April 2022. What vision does ORIX Environmental Resources Management have for its future?

A methane fermentation tank

“If manufacturers think about what happens to their waste, it will lead to advances in waste sorting,” said Hanai. “But no matter what future developments are made in the field of recycling and reusing, there will always be a need for combustion. Turning waste into energy as biogas is a way of trying to use everything that can be used. It is deeply linked to sustainability, and we want to push these technologies as far as we can.”

Kameoka added: “In the future, waste processing facilities—whether they use combustion or methane fermentation—will have to be located and used according to the characteristics of the waste in question. At ORIX, we hope that our dry methane fermentation biogas power generation facilities will increase the choice of waste processing facilities available.”

In municipalities, burnable waste is typically combusted. However, waste processing facilities are now ageing across Japan; when trying to rebuild these facilities, an increasing number of municipalities are facing difficulties both from a locational and financial perspective.

While waste power generation facilities—such as the ORIX-run Yorii Biogas Plant—are increasing in number in Japan, there are few examples of dry methane fermentation facilities. Until recently, wet methane fermentation was almost the only option available. However, the adoption of wet methane fermentation technologies has been limited—this is in part due to the difficulty of sorting and collecting only kitchen waste that is not suitable for incineration power generation. Dry methane fermentation has the potential to help overcome these challenges; and, for ORIX Environmental Resources Management, its existing large-scale recycling facilities can function as back-ups.

“We are currently aiming to increase the quantities we receive of kitchen waste and other burnable waste that people might not know how to sort,” noted Kameoka. “I have a strong desire for our industry to further improve its waste processing activities through the use of dry methane fermentation. By replacing deteriorating waste processing facilities with dry methane fermentation facilities, we will be able to improve our entire approach to waste processing—and being able to contribute to this progress makes me very happy.”

As a leasing company, ORIX recognized early-on it had a duty not only to finance but also to properly process the waste generated by its properties. Wishing to process this waste itself, the company established ORIX Environmental Resources Management. ORIX’s initial processing of waste and its subsequent full-scale entry into the waste processing business was underpinned by a desire to make use of waste as a resource; this, in turn, led to the establishment of its dry methane fermentation biogas power generation facility. Now, through this business, ORIX is seeking to further expand the possibilities of waste processing as part of its vision to help enable sustainable growth through innovative solutions.

A methane fermentation tank building

*Departments and positions are correct as of the time of writing
*ORIX employees are pictured without face masks for artistic reasons

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