VOA慢速英语听力：目前，在美国南部，较少的能量由煤产生

Tall chimneys that once released smoke into the air all day and night are now unused. The last coal-fueled generators that operated at the energy center were closed a few years ago. Trains full of coal no longer arrive at the center, and largepiles of coal no longer cover the ground.

The center is owned by Duke Energy.

Energy companies have had to sharply reduce the amount of coal they use for several reasons: Stronger government rules have reduced the level of carbon permitted to be sent into the air. And there is a growing demand for clean energy.

The new energy center is fueled by natural gas. It is a much cleaner source of electricity than coal.

Bill Wilson is the senior engineer of the Buck Combined Cycle Station. He says Duke Energy has closed about half of its coal-fueled energy centers in recent years and has replaced them with ones fueled by natural gas.

He told VOA it is less costly to fuel the plant with natural gas than with coal.

Switching over

Coal was the main fuel used to generate electricity in the United States for many years. But the U.S. Energy Information Administration says in 2015 coal and natural gas were used equally to create electricity -- about 33 percent each.

The shift from coal to natural gas is happening at energy centers throughout the country.

In July, coal was removed from the Clinch River Coal Plant in Russell County, Virginia. The plant is owned by American Electric Power. Last year, parts of the center were converted from coal to natural gas use.

Ricky Chaffin is the manager of the plant. He says it is now not only cleaner but produces more electricity.

“You don’t have to handle the coal,” he says. “You don’t have to move the coal from the pile to the plant. We’ve got a lot less equipment. So (there is) a whole lot lessmanpower required to (operate) a (natural) gas plant,” he said.

When the plant was fueled by coal, 182 people were needed to operate it. Now, 46 people work there.

The U.S. Energy Information Administration has predicted that natural gas will become the country’s largest source of electricity this year.

In North Carolina, Duke Energy plans to close most of its coal-fueled power plants in the next few decades. But as it does, it faces environmental problems.

Last month, the company reached an agreement to remove the coal ash from its Buck Steam Station that has been polluting groundwater and the nearby Yadkin River for many years.

I’m Christopher Jones-Cruise.