Step by Step 3000 第3册 Unit10:Clean air(2)

B. You're going to hear a report about a small taxi business which is leading the movement away from gasoline-powered cars, listen carefully, as you listen, take notes for each of the following questions.
The day may soon come when, instead of filling up your car with gasoline or petrol, you'll take the car to a station and fill it up like a bicycle tire, with a compressed gas, natural gas.
That will be a good day, say many environmentalists, because petrol releases pollutants into the atmosphere, whereas natural gas is much cleaner.
It comes out of the car mainly use water vapor and with no carbon monoxide.
One of the small companies is right here in Washington D.C.
The company is called Clean Air Cab, and it may be the United States's very first fleet of taxicabs powered by natural gas.
The founders are a couple of determined young entrepreneurs, Jim Doyle and Todd Ruell.
This here is a 1993 Chevrolet Caprice, one of six prototypes in the United States that was delivered by General Motors for use in the inaugural parade.
It's a computerized system for delivering natural gas to the engine.
We're hoping that this is going to be the wave in technology of the future for transportation.
For the moment, all six cabs are parked in a downtown garage.
The cabs are shiny white, with signs on them about clean air and natural gas.
Can we go for a ride? Yeah, let's take that one there, number four. We'll go for a fill up.
There have been questions about permitting signs saying "powered by clean natural gas" on the outside of the cabs and questions about natural gas itself. Is it safe? Or does it easily explode?
Todd Ruell says not to worry. Natural gas dissipates upon impact. It's like popping a balloon, it goes up. It's an inert gas, it dissipates into the atmosphere.
Yeah, but say you have a fire going as it dissipates.
If there's a fire going, it wouldn't be because of the natural gas. Impact will not cause the gas to explode.
As a matter of fact, you can take a gun and fire at the tank, and the gas will just release and go up into the atmosphere.
While gasoline is quite combustible. It will explode. And the bottom line is, it is safer than our fuelled cars today.
We drive along to the gas station.
The car sounds and feels like any other vehicle. In fact, it can switch from natural gas to petrol with a signal from built-in computer.
That's good because at times you may run out of natural gas and, as yet, there aren't so many stations available with natural gas pumps, at least in the United States.
Environmentalists have mixed feelings about natural gas, on the one hand, it's a fossil fuel, like petrol or coal, with a limited supply, on the other hand, there are large reserves still untapped.
And advocates say that natual gas could be a practical fuel to wean drivers off petrol, and eventually switch to a completely clean and renewable source, hydrogen fuel made from water.
We're pulling into the refueling center. As you can see, the fuel pump looks the same as regular gasoline pump. It just say CNG or compressed natural gas.
What we're going to now is step out and fuel, and you'll see it's quite a simple process.
Todd Ruell has taken out a kind of credit card and put it into a slot. That unlocks the gas hose and pays for the gas automatically.
He attaches the gas nozzle to the car tank, turns it slowly, and we wait as the pressure rises.
Right now, we're at about... a little over 2,000 pounds. Today...it's warmer today, so we should get about a 2,500 pound fill.
When it's very cold, the gas will compress, so you won't get as much fill as you would on a hot day, when the gas expands.
On a hot day, you can get up to 3,400 pounds of gas. As I said, today, we should get between 2,500 - 2,600 pounds, which will take us about 253 miles.
It takes about four or five minutes to fill up the car, about the same time as it does for gasoline.