主题：【讨论】现代战国策---美国的乙醇战略zt -- 泡菜

下面文章是真正的乙醇专家在SCIENCE上发的文章，你看看他怎么联系乙醇和石油的。你发文到SCINCE去指责他误导吧。可惜现在乙醇界都这样比较的，因为你不明白现在的乙醇就是这么生产的。在乙醇生产过程中，蒸发提纯耗掉了60%的能量，现在这些能量不是烧乙醇得来的，而是烧天然气得来的。在你那篇文章<生产生物乙醇的消耗>中对这一最大的能量消耗完全不提，也可见你这专家的水平了。

In their Report "Ethanol can contribute to energy and environmental goals" (27 Jan., p. 506), A. E. Farrell and colleagues offer hopeful opinions about corn-based ethanol. Their analysis suggests that, since the ratio of ethanol produced to fossil fuel used is positive, ethanol should be further developed. If replacing oil is our goal, we must look

at two parameters of this approach: (i) energy return on investment (EROI) including environmental impacts on soil, water, climate change, ecosystem services, etc.; and (ii) scalability and timing. Farrell and colleagues' most optimistic EROI of 1.2:1 (which does not include tractors, labor, or environmental impacts) implies that we need to produce 6 MJ of ethanol to net 1 MJ of energy for other endeavors.

Thus,the yield of ethanol would not be 360 gallons per acre gross yield, but rather a mere 60 gallons per acre net yield, not even two fill-ups for an SUV. The entire state of Iowa, if planted in corn, would yield approximately five days of gasoline alternative. To devote half the nation's corn crop to ethanol would require an input of 3.42 billion barrels of oil (almost half our current national use)

to net 684 million barrels of "new" ethanol energy. We would also lose food and soil nutrients, suffer ecosystem damage, and use massive amounts of water for irrigation.

We need alternative energy. But ethanol from corn is neither scalable nor sustainable. Let's pursue better options.

In their Report "Ethanol can contribute to energy and environmental

goals" (27 Jan., p. 506), A. E. Farrell and colleagues offer hopeful

opinions about corn-based ethanol. Their analysis suggests that, since

the ratio of ethanol produced to fossil fuel used is positive, ethanol

should be further developed. If replacing oil is our goal, we must look

at two parameters of this approach: (i) energy return on investment

(EROI) including environmental impacts on soil, water, climate change,

ecosystem services, etc.; and (ii) scalability and timing. Farrell and

colleagues' most optimistic EROI of 1.2:1 (which does not include

tractors, labor, or environmental impacts) implies that we need to

produce 6 MJ of ethanol to net 1 MJ of energy for other endeavors.

Thus,

the yield of ethanol would not be 360 gallons per acre gross yield, but

rather a mere 60 gallons per acre net yield, not even two fill-ups for

an SUV. The entire state of Iowa, if planted in corn, would yield

approximately five days of gasoline alternative.

To devote half the nation's corn crop to ethanol would require an input

of 3.42 billion barrels of oil (almost half our current national use)

to

net 684 million barrels of "new" ethanol energy. We would also lose

food

and soil nutrients, suffer ecosystem damage, and use massive amounts of

water for irrigation.

We need alternative energy. But ethanol from corn is neither scalable

nor sustainable. Let's pursue better options.

Nathan Hagens

Gund Institute for Ecological Economics

University of Vermont

Burlington, VT 05405,

Gund Institute for Ecological Economics

University of Vermont

Burlington, VT 05405,