Abstract
It is said that a cause of sudden rise in price of foods is partly due to the production of bio-ethanol from biomass of foods origin. If an arable land is newly obtained by clearing such as forest etc. to prevent this social issue, it causes reverse effect to original purposes to reduce carbon dioxide emission. These difficulties are assessed at for the two cases of productions of bio-ethanol using existing arable land and newly cleared land under the available statistical data and a simple model introduced. Even if the bio-ethanol production is conducted using entire cereals produced per year in the world, the product substitutes only about 43% of gasoline consumed because human beings consume enormous amount of gasoline per year. In the case of Japan, it is only 5.5%. This suggests the sudden rise of food price is inevitable. If the bio-ethanol is produced using newly cleared land, it is concluded that the effect on reduction in carbon dioxide emission never appear until several 10 years to a few hundred years later.
