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How a power plant operator keeps 100,000 tons of pollution out of the air

Jan 5, 2016

We know that burning coal produces greenhouse gases that cause global warming. But it's also a big source of other types of air pollution that can cause disease and even death.

Around the country, dozens of coal-burning power plants are racing to comply with new Environmental Protection Agency rules to keep mercury out of the air.

In Michigan, Consumers Energy and DTE Energy are both spending roughly $2 billion to comply with new air rules.

We take a tour

The Homer City Power Plant, situated just east of Pittsburgh, is also making these big changes.

At the plant, a tall crane moves steel beams into a brand new building.

Workers install new pollution controls at the Homer City coal-fired power plant.
Credit Reid Frazier/Allegheny Front

The building is home to the plant’s new pollution controls. In total, the project cost $750 million.

Why so expensive?

“I mean, just look at the size of this project,” James Shapiro says.

Shapiro is a vice president at GE Energy Financial Services, which owns the plant.

Todd Kollross, an engineer overseeing the project, points to metal air ducts that will send exhaust to the new scrubber system.

These ducts will handle airflow out of the plant’s boilers, which burn coal to create electricity. The boilers are big — the size of small office buildings.  

“Take your furnace and put it on steroids,” Kollross says. “You’re trying to heat your house; we’re trying to take care of two million homes.”

That’s how many buildings Homer City can power when it’s running at full capacity.

Electricity streams out of the plant to the mid-Atlantic grid that powers the East Coast, Chicago, and part of Michigan.

Why the new pollution controls?

The new equipment is needed because of clean air rules the Obama Administration imposed on the coal industry. These include the Mercury and Air Toxics Standards.

The Supreme Court recently sent the mercury rule back to the EPA for a re-write, but it’s still the law of the land. It’s one reason why operators have decided to close 200 old coal plants around the country.

James Shapiro says Homer City faced a crossroads when the new rules were first announced.

“You know, you didn’t have much choice,” he says. “You basically, you either put on the pollution controls or you stopped running.”

What does it take to keep 100,000 tons of pollution out of the air every year?

Sulfur in coal is a big cause of pollution. To take the sulfur out, Homer City is putting in thousands of air filters.

One of the long tubes that will house bag filters to catch pollution.
Credit Reid Frazier/Allegheny Front

Kollross takes me to a room where there are hundreds of holes in the floor. He says inside each hole will go long tubes covered with fabric bags.

They’re basically super-sized shop vac filters.

The way it works is simple high school chemistry: The coal exhaust is acidic, so the plant will spray it with an alkaline powder. The powder will absorb the pollution and particulates in the exhaust. The filters — the bags — will catch the powder.

“And you’ve got 40,000 between the two units — 40,000 bags,” Kollross says. “So all the particulate that we collect from the flue gas comes into these bags.”

As a result, the pollution goes into the landfill instead of our lungs.

The plant is on schedule to meet its final deadline in April.

But there’s one small problem: those new filters don’t really take out carbon dioxide, the main culprit in global warming. The EPA plans to limit carbon dioxide emissions from coal plants soon.

So just in case, Homer City is applying for permission to use cleaner-burning natural gas.

Click here to watch a video story on the Homer City Power Plant.

Reid Frazier is a reporter with the environment news program, The Allegheny Front.