At the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21) in December 2015, the Paris Agreement was adopted as a new international framework for reducing greenhouse gas emissions after 2020. The world has taken a major turn toward this observance. To comply with the Paris agreement, it is necessary to technologically develop the foundations of social infrastructure with new energy creation from new technological development for the targets listed in SDGs Goal 7. In particular, it is necessary to convert the environmental burden caused by the energy consumption of fossil resources, such as global warming, recycling, and renewable energy. In this article, we will explain the development trends of biocoke, a new biosolidification technology that can be formed from all biomass resources on the earth.

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The torrefied solid biofuels have come to attract attention as promising alternative fuels to coal in coal-fired power plants and industrial boilers. The torrefaction is a biomass thermal treatment conducted at mild pyrolysis temperatures and includes two distinct technologies, dry torrefaction (DT) and wet torrefaction (WT). The DT is the conventional thermal treatment conducted in the absence of oxygen under atmospheric pressure in a temperature range of 200-300℃, while the WT is a thermal treatment in hydrothermal media or hot compressed water in a temperature range of 180-260℃. Both torrefaction treatments can produce energy dense solid biofuels with better chemical, physical properties than original biomass feedstock, but recently the research activities in WT have increased due to some advantages of WT over DT. In this article, properties and challenges of thermally treated biomass by dry and wet torrefaction are summarized. Finally, comparison of energy required in torrefaction process between DT and WT is also discussed.

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The steel industry accounts for about 14% of CO₂ emissions within the industrial sectors that emit large amounts of CO₂ domestically. In this article, we suggest the possibility of introducing carbon-neutral renewable energy in steelmaking based on the results of the first CO₂ reduction large trial test in an electric arc furnace using biocoke technology. We made efforts to reduce CO₂ by using bio-coke in scrap preheating arc furnaces. In current issues, about 52% of the input energy is lost in arc furnaces, of which about 36% is lost as waste gas heat. Especially, we challenged for the first time in the world/domestic to use biocoke as a substitute for coke in electric arc furnaces. It is considered that the reaction heat of biocoke also contributed to scrap preheating. We have used biocoke in electric arc furnaces and found that coke reduction is possible. It is hoped that biocoke will contribute to the construction of a carbon-neutral society and the realization of a decarbonized society through the effective use of biocoke in various fields.

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Many initiatives at each stage in the agricultural sector from production to consumption and innovations have been taken. From a medium- to long-term perspective, this action is essential to reduce environmental impact, such as carbon neutrality, which is currently being promoted as a national policy toward specific numerical targets. Therefore, various bioenergy applications are highly anticipated about CO₂ zero emissions in agricultural production. This commentary aimed to identify the current situation of the introduction of bioenergy into agricultural production and the points for eliminating “distortions” to realizing a carbon-neutral society’s ambition. In particular, It will explain the front line of efforts to realize recycling-oriented agriculture based on carbon neutral. Next, the efforts toward the potential approach of biocoke technology as new solid bio-fuel are also mentioned.

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Horokanai Town has known to produce the most buckwheat in Japan, approximately more than 2,900 tons of buckwheat annually. In recent years, the demand for shelled buckwheat has increased. As the result, the industrial waste which included the buckwheat husks and buckwheat residues, are generated in large quantities. Currently, the town does not have an effective treatment or recycling methods in managing the wastes from the buckwheat husks and buckwheat residue. Therefore, we aimed to investigate the production of biocoke from four biomass materials: buckwheat husks, buckwheat residue, garbage, and sewage sludge. Furthermore, we also analyzed a process to reduce kerosene consumption in Horokanai Town by using biocoke as a heating fuel in the boiler. It was found that 108 tons of biocoke can be produced annually. If those biocoke are used for heating the Horokanai town government building, approximately 51.5 kl/year of kerosene and 81 tons/year of CO₂ emissions can be reduced. In addition, the incineration ash generated from biocoke boiler does not contain heavy metals and also rich in minerals, therefore it can be returned to agricultural land.

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This current study aimed to provide information on the mechanism of clinker formation and to effectively utilize the combustion ash by using a commercially available pellet stove that was commonly used for residential application. （1） Mixed combustion experiment was conducted by using the biocoke made from wood pellets. The result showed that the suggested approach was effective in improving the character of clinker when using a mixed combustion ratio up to 10%. （2） Next, a concrete material （mortar） made from the biomass combustion ash was prototyped. As the result, there was no particular problem with the workability during the filling of the formwork.

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Achieving green casting is the goal of the foundry industry. This is not only in the perspective of CO₂ reduction based on a near future to fossil resource depletion but also self-sufficient stable energy supply and avoidance of global risks. Significantly, in the cupola operation, through the history of various efforts by each company, we have reduced the coal coke ratio to the limit; in other words, we are controlling it with the minimum origin energy consumption required for melting, so we cannot reduce CO₂ by further reducing coal coke. In this article, we engaged in partially substituting foundry coke with various biocoke that have been developed recently. By partially expending （or substituting） the fuel in the cupola with biocoke made from a variety of different substances, we found the characteristics of operating cupolas and the difference in the maximum substitutional rate for foundry coke related to the substances of biocoke. Moreover, we developed the practical technology for utilizing biocoke. Especially, we have verified that the cupola operation can be operated without problems up to a conditional maximum of 20 mass% substituting of coke for the same calorific value.

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