托福听力短文 II-08-2
(MA) Scientists are always on the lookout for alternative sources of energy. Today we're going to discuss one that's so plentiful they say it could supply more energy than all the coal and oil in the world. It's found in something called gas hydrate and, believe it or not, that's a kind of ice.
That's right. But the water in this ice was way down below the Earth's surface when it was frozen, so it was under a lot of pressure. And trapped inside the crystals of ice are individual molecules of methane --- that's what's in natural gas.
All this makes gas hydrate pretty strange stuff. If you touch a match to a piece of this ice, it'll burst into flame. And when geologists bring a chunk of it up to the surface to study at normal air pressure and temperature, gas hydrate begins to hiss and bubble --- and in less than half an hour, the ice melts and the methane inside escapes into the air.
Now, as you might guess, this can make gas hydrate kind of hard for miners to handle. And then there's the problem of where it's located --- in frozen arctic regions or in ocean waters off the Atlantic coast --- and up to a mile down.
Environmentalists warn that mining it could even be disastrous. Offshore drilling could allow seawater to seep down into the huge icy deposits and release tons of methane up into the atmosphere. And methane, our listeners may recall, is a greenhouse gas that could really worsen the problem of global warming.
So, gas hydrate may offer some interesting possibilities. But, with all these drawbacks, I'm not going to hold my breath waiting for it to fuel my furnace.
