科研之友
微信
新浪微博
Facebook
分享链接
摘要
Concerns about energetic security and climate change have driven the present boom of agrofuels. Unfortunately, their development occurs before appropriate environmental impact studies have been made and a strong debate has been generated. The main arguments against agroethanol are reviewed herein. Agrofuels have a positive net energy balance; for sugarcane ethanol it is similar to 8 while for corn ethanol it is < 1.5; in theory, cellulosic ethanol may reach up to 36. CO2 emitted by bioethanol combustion does not count as a greenhouse gas; however during its production such gases are emitted. In the production of corn ethanol there is only a small saving of emissions. The reduction with sugarcane ethanol is very favorable when only gases included in the Kyoto Protocol are considered; however when other climate active compounds are considered, CO2-eq emission would surpass that produced by equivalent amounts of gasoline. Agro-ethanol production promotes the transformation of natural soils, with loss of biodiversity and enormous CO2 emissions. Intensive mono-crops promote erosion, pollute waters and decrease productivity and stability of ecosystems. Agrofuels compete for arable soils and are, in part, responsible for food price increases. The polemics about genetically engineering organisms will be exacerbated with the increased use of agrofuels. Ethanol combustion in vehicles presents some disadvantages to gasoline, does not decrease cancer risk, increases photochemical smog in cities and increases methane emission. The eventual arrival of cellulosic ethanol could improve the situation. However, the present production potential could only replace a small percentage of liquid fossil fuels, maintaining oil dependence.
- 出版日期2009-2
