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出于能源安全的考虑及对温室气体减排的关注,世界各国近些年大力发展生物液体燃料,我国政府提倡以木薯等非粮作物为原料生产燃料乙醇。但一直以来科学家们对生物液体燃料的碳效应争论激烈,争论的焦点在于原料种植对土壤碳库的影响及不同技术条件下副产品利用的评估。本文通过建立碳平衡分析模型,将原料种植对土壤碳库影响及副产品利用的替代效应纳入研究体系,评估了我国木薯燃料乙醇生命周期内的碳排放,研究结果显示:我国每生产单位质量(1kg)木薯燃料乙醇,在新旧两种技术条件下的碳排放分别为0.457kg和0.647kg。碳排放主要来自于氮肥的使用、木薯种植对土壤碳库的破坏及木薯燃料乙醇加工转化过程能源投入,在新技术条件下分别占总排放量的9%、29%和50%。以汽油的碳排放为参照,在旧技术条件下我国木薯燃料乙醇碳排放呈现负效益,在新技术条件下其碳排放为汽油的90%,倘若能避免对土壤碳库的破坏,则这一比例将下降到64%。因此,为了促进我国木薯燃料乙醇的发展,首先应该引导农民合理施肥,利用边际土地种植木薯,不转换林地、草地等土地类型的利用方式;此外,要开发高效节能的燃料乙醇转化技术及加强对副产品的二次利用。
For the sake of energy security and attention to greenhouse gas emission reduction, all countries in the world have vigorously developed biological liquid fuels in recent years. Our government advocates the production of fuel ethanol from non-grain crops such as cassava. However, scientists have long been debating the carbon effect of bio-liquid fuels. The debate has focused on the impact of raw material planting on soil carbon stocks and the evaluation of by-product utilization under different technical conditions. In this paper, the carbon balance analysis model was established, which included the effect of raw material planting on soil carbon pool and the substitution effect of using by-products into the research system, and evaluated the carbon emission of cassava fuel in the life cycle of our country. The results showed that the mass per unit production ) Cassava fuel ethanol, carbon emissions under the new and old two technical conditions were 0.457kg and 0.647kg. Carbon emissions mainly come from the use of nitrogenous fertilizers, destruction of soil carbon pool by cassava planting and energy input from cassava fuel ethanol processing and conversion processes, accounting for 9%, 29% and 50% of the total respectively under the new technical conditions. Taking the carbon emission of gasoline as a reference, the carbon emissions of cassava fuel in our country are negatively benefitted under the old technical conditions. Under the new technical conditions, the carbon emission is 90% of that of gasoline. If we can avoid the damage to the soil carbon pool, The proportion will drop to 64%. Therefore, in order to promote the development of cassava fuel ethanol in our country, we should first guide peasants to use fertilizers rationally, make use of marginal land to grow cassava, and do not change the utilization of land types such as forest land and grassland. In addition, to develop energy-efficient fuel ethanol conversion technology and strengthen Secondary use of by-products.