As an example of definition in law, Japanese case is shown below. On January 25, 2002, the Law on Special Measures for Facilitating the Use of New Energy Sources (New Energy Law) was partially amended, and biomass was for the first time recognized as a new energy source in Japan. Fig. 2.1.1 shows the position of biomass among other “new energies”. Formerly, biomass had been considered as merely a kind of renewable resources, but the amended law now sees it as an independent category of new energy. However, some wastes, such as paper waste, food waste, demolition waste, and black liquor, are considered to be recyclable resources as well according to circumstances, and they are not strictly classified.

2.1.2 Characteristics of biomass energy

Up to the 19th century, biomass in the form of firewood and charcoal was the main source of energy, but these were replaced by coal and oil in the 20th century. In the 21st century, however, biomass shows signs of being revived because of the following characteristics: it is renewable, it is storable and substitutive, it is abundant, and it is carbon neutral.