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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。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。论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产各个环节的碳排放,研究结果显示:木薯原料种植环节碳排放主要来自氮肥的使用及对土壤碳库的破坏;木薯燃料乙醇加工转化环节碳排放主要来自蒸馏和脱水过程能源消耗,改进加工转化技术对减少此环节碳排放至关重要;木薯燃料乙醇运输及储存过程碳排放较小。在现有生产技术条件下,生产单位质量(1 kg)木薯燃料乙醇平均碳排放为0.647 kg。以汽油的碳排放为参照,在目前技术水平条件下,我国木薯燃料乙醇碳排放呈现负效益;采用较为先进的双酶法中温喷射液化—大罐浓醪间歇发酵—多塔多耦合差压精馏和分子筛变压脱水技术,则其碳排放为汽油的90%;倘若能避免对土壤碳库的破坏,则这一比例下降到64%。因此,为了促进我国木薯燃料乙醇的发展,减少木薯燃料乙醇生产的碳排放,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,减少对土壤碳库的破坏;此外,要开发高效节能的燃料乙醇转化技术并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. Scientists have long been debating the carbon effect of bio-liquid fuels. The debate has centered on the impact of raw material planting on soil carbon stocks and on the use of by-products under different technical conditions. By establishing a carbon balance analysis model, the paper included the effect of raw material planting on soil carbon pool and the byproduct substitution effect into the research system, and evaluated the carbon emissions from all aspects of cassava fuel ethanol production in China. The results showed that the main carbon emissions from cassava raw material planting From the use of nitrogen fertilizer and soil carbon pool damage; caustic fuel ethanol conversion part of the process of conversion mainly from the energy consumption of distillation and dehydration energy consumption, improve processing and conversion technology to reduce this part of the carbon emissions is crucial; cassava fuel ethanol transport and storage process Carbon emissions are small. Under the existing production technology, the average carbon emission of cassava fuel ethanol per unit mass (1 kg) was 0.647 kg. Taking the carbon emission of gasoline as a reference, under the current technological level, China’s ethanol emissions from cassava fuel have a negative effect; using the more advanced dual-enzyme method in mid-temperature spray liquefaction - batch fermentation of large mash intermittent fermentation - Distillation and molecular sieve pressure dehydration technology, the carbon emissions of 90% of gasoline; if the destruction of the soil carbon pool can be avoided, then the proportion dropped to 64%. Therefore, in order to promote the development of cassava fuel ethanol in our country and reduce the carbon emission of cassava fuel ethanol production, 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 woodland and grassland, In addition, the development of energy-efficient fuel ethanol conversion technology and to strengthen the secondary use of by-products.