VOA标准英语2014--Eagerly-awaited Technology Turns Garbage into Fuel

Eagerly-awaited Technology Turns Garbage into Fuel

When a garbage truck dumps its smelly cargo 1 onto the tipping floor at the Fiberight company’s pilot plant in southern Virginia, manager Randy Garrett sees fuel in the making.

“This is the truly remarkable 2 part,” he said. “This was slated 3 for the landfill. This was going to be buried.”

Fiberight is one of several companies that plans to turn garbage ? and in other cases, corn stalks and wheat straw ? into biofuel ethanol that can power vehicles, in a development that lends credence 4 to the old adage 5, "one person's trash is another's treasure."

 It's one of the most eagerly awaited technologies in alternative fuel and is expected to break into the mainstream 6 this year.

The biofuel is known as cellulosic ethanol, and if successful, supporters say it could provide an abundant source of energy while quieting critics who say the growth of the biofuel business has put a strain on food prices and the environment.

Ethanol makes up about 10 percent of the U.S. fuel supply and is expected to grow under a 2007 law.

Nearly all of it, however, has been made from corn. Critics say the demand for corn ethanol has created competition between food and fuel that is raising food prices. Environmentalists say farmers are plowing 7 more land to grow corn and using more fertilizers and pesticides 8, generating more pollution.

Fuel from trash

Back at the Fiberight company's pilot plant, after recyclables, used clothes, and the occasional dead animal are filtered out, about half of the garbage will be turned into energy.

A giant pressure cooker turns the rotten vegetables, paper, cardboard, and any other plant-based matter into a steaming mass of grey pulp 9, unimpressive to an outsider.  But Garrett sees it differently.

“This is the good stuff,” Garrett said. “This is what we’re after for our energy conversion 10.”

That grey pulp is mostly composed of cellulose, a natural polymer that, under the right conditions and with the right enzymes 11, can be broken down into sugar.

It’s then a simple job to turn that sugar into ethanol.

Other companies are exploring ways to use cellulose from crops grown specifically for energy like switchgrass or miscanthus, which would produce far fewer greenhouse gases than petroleum 12 fuels do.

Unanticipated challenge

When President George W. Bush signed the Energy Independence and Security Act in 2007, it was anticipated that cellulosic ethanol was right around the corner.

For example, for 2013, the bill mandated 13 that gasoline makers 14 use 62.6 billion liters of renewable fuels, of which 3.8 billion liters were to be cellulosic ethanol.

That turned out to be easier said than done.

University of Illinois agricultural economist 15 Madhu Khanna says scientists know how to make cellulosic ethanol in the lab but, “The main problem is doing that in a continuous way, cost effectively on a large scale.”

Regulators had to lower the requirement to 22.7 million liters.

Market limits

This year could be a turning point as several bio-refineries come online, but there is a limit as to how much the industry can grow.

“Even if we can begin to produce this cost effectively, we need to be able to consume it as well,” Khanna said.

Only a few models of cars can handle high ethanol fuel.

She said that consumers have little incentive 16 to buy them, or to buy the fuel, which can be more expensive than gasoline.

That means without a change in the market, there is only so much gas from garbage that will sell.