Biomass Classification

Definitions of Biomass and Biorefinery

  Biomass is a renewable organic material that is derived from plants and animals. Biomass contains stored chemical energy from the sun that plants produce through photosynthesis. Biomass can be burned directly for heat or converted into high-value products such as energy and food ingredients through various processes. The concept of producing biofuels and biomaterials from biomass is called a biorefinery. Our research group conducts a generational component analysis of biomass, bioconversion research of main components (carbohydrates), and recovery and application research of bioactive substances to develop a bioconversion process platform for biomass. 

  Different generations of biomass have different compositions of main and active ingredients due to differences in origin/production season/processing methods, etc. To design a bioconversion process specific to biomass, a component analysis/processing/utilization strategy is required. Therefore, we are researching to establish a foundation for biomass bioconversion processes through generational biomass libraries. To date, our research group has completed the detailed compositional analysis of more than 50 types of biomass. The table below shows a partial list of the components of the analyzed biomass. 

1st Generation (Edible Biomass)

  First-generation biomass is derived from edible biomass, such as corn and sugarcane. However, first-generation biomass has the disadvantages of (1) competing with its utilization as food, which can affect food price fluctuations, and (2) requiring large areas of land and large amounts of water for biofuel production, which can be a major factor limiting biofuel production.

  Our research group has researched to optimize the extraction process of valuable compounds (e.g., anthocyanins and flavonoids) from edible biomass, such as sea buckthorn berries and elderberries. These extracts are rich in phenolic compounds, which have the potential to be used as excellent functional materials in the food and pharmaceutical industries.

2nd Generation (Lignocellulosic biomass)

  Second-generation biomass is non-edible biomass, which is lignocellulosic biomass such as wood, grass, and straw. Compared to first-generation biomass, it has the advantages of (1) lower cost and (2) not competing with food crop production. However, it is mainly composed of lignin, cellulose, and hemicellulose, which requires more complex and detailed processes for bioconversion.

  Our research group has conducted research to recover fermentable sugars from second-generation biomass, such as canola straw or barley straw, by alkali and acid treatment or enzymatic saccharification. We have utilized biomass hydrolysates to produce antibiotic precursors, bioenergy, or biochemicals.

3rd Generation (Algal Biomass)

  Third-generation biomass is macroalgae and microalgae. Compared to first- and second-generation biomass, they grow faster, require less land, and can grow in places that are not arable. However, the production of algae on an industrial scale requires large amounts of water.

  Our research group has been continuously conducting biorefinery research on macroalgae and microalgae. We specifically analyzed the carbohydrate composition of macroalgae (e.g., brown seaweeds) and reported their potential as feedstock for alginic acid, glucan, and mannitol. We also designed processes for sugar recovery/ biochemicals fermentation and bioactive substances extraction from microalgae (e.g., Nannochloropsis, Tetraselmis). We will continue to explore the potential for industrial utilization of various macroalgae and microalgae.

4th Generation (Organic Waste)

  Fourth-generation biomass is organic waste such as agricultural residues, crude glycerol, fruit peels, fruit juice processing residues, spent coffee grounds, waste cooking oil, and waste sludge. These organic wastes have the advantages of not requiring agricultural land, low cost, and year-round availability. Hence, organic waste is recognized as an attractive feedstock for biorefineries because its upcycling can prevent environmental pollution by conventional treatment (landfill and incineration) and enables the production of high-value products.

  Our research group has conducted biorefinery research on various organic waste (e.g., chestnut shell, peanut shell, spent coffee grounds, orange peel, and persimmon calyx) generated from agricultural/food processing processes. Specifically, we designed a biomass-customized sugar recovery process, and the recovered sugars (e.g., glucose, xylose) were used for fermentation of bio-chemicals (e.g., lactic acid, ethanol, and bacterial cellulose). Also, we designed the extraction processes to produce natural antioxidants from various biomass.