1.2.1 General scope

Biomass resource can be utilized substantially in endless number of times, on the basic rail of carbon circulation by photosynthetic process. On the other hand, a fossil resource is limited to a transitory use in principle. Additionally the irreversal emission of CO2 caused by fossil combustion gives serious influence on global climate (Fig. 1.2.1). R.= resource.

r<—————- plant———- <———— 1

[Biomass R.]^(use)^CO2(————— »Atmospheric CO2)

[Fossil R.]^(use)^CO2(———— ^Atmospheric CO2)^ CO2 accumulation/air

Fig. 1.2.1. Comparison of biomass and fossil system on Carbon cycling.

But the words “renewable” and “sustainable” are not always same meaning. The recycling power of plants is founded on a very delicate base of ecosystem.

The conditions for the bio-system are, maintaining the balance of harvest vs. growing speed, and the environment protection of the farming land. If not, long term sustainability of the biomass system will be fading out.