1.2.3 General scope

For the utilization of biomass, a raw biomaterial is selected among various kinds of biomass by taking into consideration of its utilization purpose, demand and availability. Then, the raw material is converted to new material or energy.

Biomass as bioresource comes mainly from plants and their debris. Animals and microorganisms as well as their organic matters are also important. Many species of plants are useful as biomass. Land biomass mainly consists of herbal biomass from major farm crops, and woody biomass from forest. Many of them are cultivated, converted and utilized for specific purposes. Aquatic biomass from oceans, lakes and rivers can also be cultivated in such a case as kelp. Biomass which is cultivated on farm land or felled from forest for specific purposes is called virgin biomass, whereas the discarded biomaterials in production, conversion and utilization processes are named waste biomass and used for other purposes. For example, bagasse which is the waste of sugarcane processing is used as excellent fuel for the sugar extraction and ethanol distillation processes. Utilization of waste biomass is also important for avoiding the conflict of bioenergy utilization with food and feed. Bagasse is also considered as one of the major raw materials for “the second-generation biofuel”.

Transportation and storage of biomass is not easy because of its bulkiness and degradation. It is, therefore, reasonable to use biomass in the areas where it is produced. For this reason, biomass is used in or nearby regions where biomass supply and demand are balanced. However, when biomass is converted into more transportable form like densified pellet or liquid fuels, it can be utilized in distant regions.

Biomass can be used either as materials or energy. Biomass is utilized as diversified materials such as food, feed,
fiber, feedstock, forest products, fertilizer and fine chemicals. Utilization as energy in the form of biofuels occurs on the final stage and biomass is decomposed into carbon dioxide or methane and emitted in the air. The diversified use can be called ”8F Use” of biomass.

Biomass can be used stepwise like a cascade as its quality is degraded. Fig. 1.3.1. illustrates examples of cascade use of food to feed and then to fertilizer.

Food waste can be treated into good feed. Feed changes into livestock manure which can be fermented into methane. The digested sludge can be used as fertilizer. Forest products such as wood from pulled down houses can be utilized as particleboard or pulp, and as the final step, it can be converted into energy through the combustion of bio-solid fuel.

Recycling is made for paper, fiber, some feedstock and wood products as shown with round-arrows in Fig. 1.3.1. So far as biomass is used as material, its carbon is kept in the material and does not emit any greenhouse effect gas contributing to reduce the ill effect of global warming.