av无码免费岛国动作片,在线成人小视频,日韩国产亚洲欧美中国v

Download

The increased use of corn-derived ethanol and other bio-fuels has been blamed for rising food prices worldwide. But defenders of these fuels say their impact on food prices is being exaggerated and that new fuels under development will largely bypass that problem in any case. VOA's Greg Flakus has more on the story from College Station, Texas.

American corn, wheat and soybean fields feed much of the world and also provide the material from which alcohol fuels like ethanol are produced.

Ethanol has benefited the U.S. heartland by giving farmers more stable prices for their grains and creating jobs at rural refineries, some of which are owned and operated by local farmers.

Federal law requires the use of ethanol in gasoline, usually at around 10 percent, but some flex-fuel vehicles can also use an 85 percent mix.

But critics say congressional mandates to use ethanol are ill-conceived. They note that corn-derived ethanol generates less than two units of energy for every unit used to produce it. Even ethanol promoters agree that the future lies in using more non-food material, like corn stalks, to produce what is called cellulosic fuel.

"I believe the first cellulosic biofuel that is commercialized will probably come from some sort of agricultural residue, meaning that it will grow on a farm and a farmer will sell it to a biorefinery," said Brian Jennings, who represents the American Coalition for Ethanol. "We strongly embrace cellulosic ethanol alongside corn ethanol. The fact of the matter is we need both."

One of the most promising replacements for corn in producing ethanol is sorghum, a grass that can produce grain used in some foods and in animal fodder.

Bill Rooney, who runs the sorghum project for Texas A&M University, says sorghum-derived fuel could start having an impact on the market within five years.

"If we are talking about a sugar platform, one that is very similar to sugar cane, we can use sweet sorghums to do that in the very near future," he noted. "If we are looking at cellulosic, the whole plant and all the fiber, then we are looking at systems that are a little bit longer out."

This is just one of the areas of research at Texas A&M. that could provide biofuels for transportation. Fossil fuels like oil and coal originated from ancient plant material, compressed and heated over millions of years, but scientists in laboratories here can produce fuels directly from harvested plant material.

Mark Hussey, who oversees agriculture programs at Texas A&M, says a lot of research is directed at getting gasoline-like fuel directly from plant material.

"We are producing a product that is identical to the product that would be produced from a barrel of oil and we are producing it strictly from plants," he said.

One of the most promising areas of research is algae, which is grown in ponds rather than fields.

"Algae produces about 60 percent oil on a dry-weight basis, 60 percent of the material is oil," explained who heads the Texas A&M Department of Soil and Crop Sciences.. "With soybeans it is about 17 or 18 percent oil."

He says using algae for fuel also helps reduce greenhouse gases, because they can be used with the algae to create energy.

"We can pump excess CO2 from manufacturing processes or whatever into the ponds and the algae converts it because it needs it for photosynthesizing," he added.

The new bio-fuels could be running many automobiles in a few years, but Mark Hussey cautions that they are unlikely to replace oil as the main transportation fuel. What they will do, he says, is help offset the rapid growth in energy demand.

"Hopefully, if we can take care of this increased growth in demand that we have got for energy, both in this country and globally, with bio-based fuels, we will go a long way to solving the energy issues," he explained.

Hussey says development of bio-fuels should not offset agricultural enterprises that produce food, feed and fiber. But he says much of the bio-fuel production can be done on marginal lands so as to avoid a food-versus-fuel competition over land resources.

sorghum: 高粱屬植物

(Source: VOA 英語點津姍姍編輯)