A challenge to "resource recycling" that connects local communities and groups

Mr. Kobayashi: Our company's roots lie in the logistics and warehousing business, which has been around for over 200 years. Currently, as a general trading company handling the commercial flow, we are developing diversified sales businesses including oil, gas, and building materials. In 2016, as a new challenge, we launched the biogas business with the Suzuyo Kikugawa Biogas Plant. It all started with the idea of how we could utilize the energy handling expertise we have cultivated over many years, and the know-how of "handling materials properly," which is the group's original business, in a new energy cycle called methane fermentation.

Mr. Maeda: The greatest feature of this biogas business is its circular structure, which is almost entirely self-contained within the Suzuyo Group. For example, SSK Foods Corporation, which handles food manufacturing within the Suzuyo Group, provides a stable supply of food waste, which is the main raw material for methane fermentation. In addition, we can procure the chemicals necessary for processing from our own chemical division, and these synergies unique to a trading company are a major factor supporting the stability of the business.

Mr. Kobayashi: The specific impetus for constructing the plant was the waste problem the local community was facing. At the time, Bellfarm Co., Ltd., which was engaged in agricultural production on land adjacent to our company, was experiencing a rapid increase in agricultural residues such as stems and leaves due to the expansion of tomato production, and the processing capacity of the local incineration facility was approaching its limit.
Furthermore, the sludge produced by food processing plants has a very high water content, and burning it would consume an enormous amount of energy. Therefore, driven by a strong desire to reuse unused resources as energy rather than waste them, we chose the wet methane fermentation method, which can efficiently extract energy even with a high water content.

Mr. Maeda: At the Kikugawa Biogas Plant, we are not only generating electricity, but we are also working to realize a more advanced regional circular agriculture system by refining CO2 from the exhaust gas during power generation and using it to promote photosynthesis on the farm, and by returning the digestate produced during the fermentation process to the farmland.

▲Suzuyo Group's Biogas Utilization Initiatives: Project Overview

▲Exterior view of the Suzuyo Kikugawa Biogas Plant. The large building is the processing building, and the tank-like structures on the left are the fermentation tanks.

The unavoidable challenges of methane fermentation are the treatment of fermentation residue and the enormous costs involved.

Mr. Maeda: One unavoidable challenge in operating a biogas plant is the treatment of fermentation residue*. Our company uses proprietary technology to efficiently break down lipids, which allows us to reduce the amount of fermentation residue discharged compared to typical plants. However, due to the nature of methane fermentation, a certain amount of fermentation residue inevitably remains.
The challenge lay in figuring out how to handle this appropriately and how to process it in a way that added value.

*In this article, the digestate and sludge generated during methane fermentation are collectively referred to as "fermentation residue."

▲Fermentation residue after methane fermentation and dehydration. Dehydration alone is not enough to remove all moisture, and it still feels damp to the touch.

Mr. Kobayashi: This issue has persisted for about 10 years since the plant was established, and the cost of processing this fermentation residue accounted for nearly half of the plant's operating costs, excluding personnel expenses and other costs. From a business perspective, it was an enormous cost burden.

Mr. Maeda: Also, from the perspective of our company's vision of "achieving zero emissions," the processing of fermentation residue was an important issue. Even if we accept local waste and convert it into energy, if it is ultimately discharged back into waste, it cannot be called a true cycle. Until now, we had been using a dewatering machine to reduce the moisture content to about 80% of the dewatered sludge, and then outsourcing composting or fuel production to external companies, but we wanted to "take a more proactive approach ourselves."

Mr. Kobayashi: Initially, we explored the possibility of having farmers use the dewatered sludge with an 80% moisture content as fertilizer, but reality was not so kind. In its unprocessed state, it is quite heavy and difficult to handle, so it does not have high added value as fertilizer. In order to distribute it widely to the general public and reuse it effectively, it was essential to further dry it to increase its added value and process it into a form that anyone can easily handle.

The deciding factors were achieving "odor elimination" to coexist with the local community and "utilizing surplus energy."

Mr. Maeda: To be honest, from the perspective of those on site, there was a part of us that had given up on the idea of drying the equipment. Normally, introducing a dryer inevitably comes with the risk of odor, and there was limited space to retrofit new equipment into the already completed plant.

However, MeltKing IoT is a very compact, ready-made packaged product, and its size allows it to fit neatly into even limited spaces. We were confident that "with these specifications, we can overcome the long-standing problem of fermentation residue while maintaining harmony with the local community."

Mr. Kobayashi: When introducing MeltKing IoT *, we also placed great importance on the issue of "smell." As you can see, our plant is surrounded by vast tea plantations, which are symbolic of Shizuoka. Farmers are very sensitive to smells.

Given the nature of our waste disposal business, we cannot achieve coexistence if we give local residents the impression that we are a "nuisance facility that emits odors." The fact that our facility operates near Shin-Yokohama Station, where Macnica 's headquarters building is located, and yet produces absolutely no noticeable odor, was a huge draw for us.

Mr. Maeda: To be honest, from the perspective of those on site, there was a part of us that had given up on the idea of drying the equipment. Normally, introducing a dryer inevitably comes with the risk of odor, and there was limited space to retrofit new equipment into the already completed plant.

However, MeltKing IoT is a very compact, ready-made packaged product, and its size allows it to fit neatly into even limited spaces. We were confident that "with these specifications, we can overcome the long-standing problem of fermentation residue while maintaining harmony with the local community."

▲Fermentation residue dried with MeltKing IoT loses most of its moisture and its volume is significantly reduced, making it easier to transport.

Mr. Kobayashi: Another major deciding factor was the customizability of the heat source. Our plant has extremely high efficiency in lipid decomposition, resulting in approximately 1.2 times more biogas than initially designed. Until now, we had no choice but to burn the excess gas that we couldn't use even with the generator running at full capacity, but we thought, "Could we reuse this as a heat source for MeltKing IoT?"

Mr. Maeda: Originally, MeltKing IoT is designed to use city gas or LP gas as a heat source, but theoretically it can also be used with biogas. Therefore, the opportunity to collaborate with Macnica to tackle this challenge of "stable supply using biogas" was of great significance.

By using surplus energy that was previously wasted as a heat source for drying, we significantly reduced running costs while increasing the added value of the fermentation residue. This was truly the moment when our company's strengths and challenges were connected in a single circle by MeltKing IoT.

A transformation from "discarding" to "creating," deepening collaboration with local businesses.

Mr. Maeda: The most direct result of the implementation is undoubtedly the significant reduction in processing costs, which had been a long-standing concern. At the same time, the fact that we were able to create a resource recycling loop that goes beyond mere waste disposal is of great significance to our company.

The main reason methane fermentation hasn't become widespread in society until now is the bottleneck in processing the residue. However, with the introduction of MeltKing IoT, the exit strategy has become clear, and the establishment of a solid cooperative relationship with fertilizer manufacturers and boiler companies will be a great asset for the future.

Mr. Kobayashi: The fermentation residue that we previously disposed of at great cost has been transformed into valuable resources such as fuel and fertilizer through MeltKing IoT. In addition, waste from local school lunches is fermented and dried to make fertilizer, which is then returned to the community.

If we can establish such a demonstration model for "local production and consumption of resources," it will be a big step towards realizing a decarbonized society. At a time when rising prices and supply uncertainties of imported fuels are a concern, we believe that having a system to stably procure energy ourselves is extremely important from a national security perspective.

The impact of this successful model extends beyond simply improving our own facilities. It will serve as a valuable "real-world example" for providing consulting and implementing similar strategies to other municipalities and companies facing similar challenges. The fact that we have a fully integrated system for transforming waste into resources and circulating it as local energy is, in itself, a significant advantage that sets us apart from our competitors.

Based on the demonstration model, we aim to grow the circular economy hub.

Mr. Maeda: We would like to further expand the successful model for utilizing MeltKing IoT that we have established through this initiative. Being able to present concrete solutions based on our own demonstrations to the major challenge of fermentation residue treatment, which has hindered the spread of methane fermentation, is a great strength for our company.

Mr. Kobayashi: We are currently looking to further strengthen our collaboration with the local community. For example, we are considering working with local governments and farmers to discuss the use of fertilizer in farms and green spaces within the city. If we can create a food cycle where the leftovers from school lunches that children eat are turned into fertilizer, which is then used to grow vegetables in the local area, it will also contribute to local education.

Mr. Maeda: In addition to local governments, one of our plans is to collaborate with neighboring companies that have employee cafeterias. We would recycle the waste generated from the cafeterias into fertilizer, which would then be used to maintain the green spaces on the company's premises. Furthermore, if Bellfarm's tomatoes were used as ingredients in those cafeterias, it would be possible to create a self-contained circular loop within the company.

Mr. Kobayashi: We hope to develop this plant into a "circular hub" that supports the sustainability of local communities and businesses. Unused resources will be transformed into something valuable, and in turn, it will return prosperity to the community. Now that we have a reliable solution in MeltKing IoT, we want to accelerate our progress toward realizing this vision.

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