Sustainable Bio-Ethanol Production in Relation to Water and Soil Resources in Iran

Due to overuse of fossil fuels in the world¡ the idea of renewable energy production¡ especially biofuels has been popular. On the other hand¡ production of bio-ethanol is one of the 15 potential technologies for sustainable atmospheric CO2 production in 2054. However¡ the following strategic questions should be answered: 1- Should the crop residues be used for increasing the soil organic matter¡ soil quality and improvement of ecosystem or for energy production? 2- Should the short term positive economic benefits be preferred to the long term sustainable use of natural resources? 3- Should the need of fuel be preferred to the food security in the world? Responses to these questions are related to the point that more land and water resources should be devoted to produce bio-energy plants. Raw materials for bio-ethanol production are: Sugar rich crops (sugarcane and sugarbeet)¡ starch crops (wheat¡ maize and potato)¡ and cellolusic materials (crop residues¡ wheat straw¡ rice straw¡ maize stover and woods). However¡ use of sugar rich and starch materials resulted in food-fuel competition that resulted in raising the food price in the world. To confront with this problem¡ the following questions should be considered: 1- Which crops should be planted for bio-ethanol production? 2- Where these crops should be planted? 3- How these crops should be cultivated for sustainable bio-ethanol production? Cellolusic energy crops that produce high biomass in soils with low fertility¡ water stress and saline conditions and are tolerant to pests and diseases are suitable choice. Energy use in agricultural sector in Iran is about 4% of the total energy use¡ on the other hand¡ there is organic matter deficit in soils¡ scarcity in water resources and forage in Iran. Therefore¡ using solid waste¡ forage or sugar rich and starch crops for bio-gas¡ electrical energy or bio-ethanol production is not acceptable. Whereas¡ natural gas or other renewable energy like solar¡ wind or nuclear energy can be used for electricity production.