Coal is back; so are concerns over pollution

Big Stone Power plant
Ottertail Power Co. plans to build a second coal-fired power plant at its Big Stone site.
MPR Photo/Mark Steil

From the time you pop a bagel in the toaster for breakfast, until you turn off the bedside lamp, you're using electricity, and on average more than half of that electricity comes from a coal-burning power plant.

Coal-burning power plants are also a major source of air pollution. According to the Environmental Protection Agency, the average coal-fired power plant produces 2,249 pounds of carbon dioxide, 13 pounds of sulfur dioxide, and six pounds of nitrogen oxides for each megawatt hour of electricity.

Carbon dioxide is thought by many scientists to be a major contributor to global warming. Sulfur and nitrogen oxides contribute to acid rain. Nitrogen oxides react with sunlight to form ozone. Power plants also emit tiny ash particles which can cause health problems when inhaled, and mercury, which can impair brain development.


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But coal is plentiful.

In fact, the U.S. has the largest known coal reserves in the world. Rising oil and natural gas prices make relatively cheap coal a popular choice for producing electricity. About 150 new coal-fired power plants are on the drawing board.

Coal truck
Coal is resurging as a primary fuel in power plants across the country, mainly because the price and availability of other sources like natural gas is not as favorable.
Photo by Ian Waldie/Getty Images

"Ottertail and others are looking at coal again," says Jeff Endrizzi, who manages the Ottertail Power Company's Big Stone power plant just across the Minnesota border in South Dakota. Endrizzi says coal is the most affordable fuel for power plants.

"We've all seen what happened to natural gas prices. That was really in vogue as a source for fuel for power plants in the '90s. We've seen what happened to the market for that. Coal is really back in the spotlight," Endrizzi says.

With the spotlight comes some heat from those who say power plants aren't doing enough to clean up their smokestack emissions. There were some old power plants grandfathered in when the Clean Air Act was passed in the 1970s. At the time, the industry said those dirty plants would soon be shut down, but some are still running.

Coal-fired power plants built now will generate less air pollutants than many existing plants, but they will still be a major source of air pollution.

No one denies coal is a dirty fuel, but there's debate between those who say the smokestacks should be cleaned up at any cost, and people in the power industry who say pollution equipment has to be affordable, so it doesn't drive up the cost of electricity.


Jeff Endrizzi knows the challenges of smokestack pollution.

The Big Stone plant was trying to reduce particulate emissions from its smokestack to reduce opacity. Opacity is a measure of the fine particles coming out of the plants smokestack. These particulates are the tiny ash particles left when coal is burned, and exposure to the particles can cause respiratory diseases and heart problems. There were times in the past when the plant exceeded it's opacity permit, it's currently within permitted emissions.

control room
The air filtering system at the Big Stone power plant is nearly a block long and five stories high.
MPR Photo/Dan Gunderson

The Big Stone plant was using an electrostatic precipitator to trap the ash. An electrostatic precipitator operates much like an air purifier you might use at home to remove dust and pollen. It takes a large filter to clean the air from a coal-fired power plant. The Big Stone filtering system is five stories high, and 270 feet long.

Big Stone engineer D.J. Haggerty leads the way along a catwalk five stories up, and into the control room for this giant air cleaner. The sound of thousands of volts of electricity passing through banks of equipment makes conversation difficult.

"It has 35,000 volts going through it right now. Pretty good charge down there," explains Haggerty.

The electricity is used to create an electrical charge that attracts the tiny ash particles to metal plates. At regular intervals, a hammer raps the metal plates and the ash falls into pits, where it's collected and used to make concrete.

filter tubes
Ottertail Power discovered an experimental air filter reduced plant efficiency and increased maintainance.
MPR Photo/Dan Gunderson

But this equipment wasn't removing enough ash particles from the smokestack emissions at the Big Stone plant, so Ottertail Power Co. decided to try an experimental technology developed at the Energy and Environmental Research Center in Grand Forks, North Dakota.

The new technology combines two common smokestack cleaners, an electrostatic device Big Stone was already using, and something called a baghouse. A baghouse is essentially a huge cloth filter air passes through before going up the smokestack.

In this case, dozens of fabric tubes are hung in the power plant exhaust ducts. As the bags get covered with ash, a burst of air snaps them, much like shaking dust from rug.

This system was designed to remove 99.999 percent of particulates, what researchers call achieving "five nines," or as near 100 percent as technically possible. The filtering would also capture some of the mercury escaping up the smokestack attached to ash particles.

A small pilot project worked very well, but when the $13 million project went online, there were immediate problems. The hybrid filtering system only works when the plant runs at about 70 percent of capacity. That means instead of generating 450 megawatts of power, the Big Stone plant is limited to about 400 megawatts.

Jeff Endrizzi
Jeff Endrizzi, manager of the Big Stone plant, says coal will be a major energy source in the future.
MPR Photo/Dan Gunderson

Plant Manager Jeff Endrizzi says those limits can cost the plant thousands of dollars an hour.

"A day like today, when power is going for $400 a megawatt hour and we're restricted 50 megawatts from what we should be running at, those are real dollars," says Endrizzi. "That's either opportunity sales, or power we have to buy on the open market."

Ottertail has given up on this experiment. The experimental filtering system will be torn out, and Ottertail will spend millions more replacing it with a traditional, proven system. Endrizzi is glad Ottertail tried the new system, but he's not sure he'd do it again.

"Utilities tend to be conservative. It's hard to stick your neck out with something that isn't proven," says Endrizzi. "We stuck our necks out a ways and it didn't pan out this time. Will we stick our necks out next time? I don't know."


And that's one of the barriers to cleaning up coal-burning power plants. Utilities don't want to invest in technology that's not proven, and it can take years to demonstrate a pollution control system works and is reliable.

Researchers refer to that demonstration phase as the valley of death, because it's where many new technologies fail.

Air pollution
Steam and exhaust rise up from the smokestack of a coal-burning electric power plant. Coal is blamed by environmentalists as a leading source for carbon dioxide, one of the three main gases causing the "greenhouse effect" and warming the earth's temperature.
Photo by Sean Gallup/Getty Images

But experts say caution is important, because new technology can have unintended consequences. For example, in recent years many power plants put new equipment on their smokestacks to remove nitrogen oxide, a pollutant that contributes to acid rain and ozone. But the process of removing nitrogen oxide created sulfur oxide, another acid pollutant.

Basin Electric Cooperative operates several coal-burning power plants in North Dakota, including one of the dirtiest plants in the country. Company spokesman Darryl Hill insists his company has reduced pollution, and continues to spend money on pollution control.

While it's true acid emissions like sulfur and nitrogen oxide have been reduced, mercury and carbon dioxide remain major pollutants being emitted from the plants.

Hill says power companies need to be cautious about new technology, and the federal government should spend more to help the companies afford it. Hill says power companies have to keep the price of electricity down and return a profit.

"What is it going to cost me to build that plant, and what are my guarantees that when this plant is built and operating -- is (it) going to be competitive with the current market prices?" asks Hill. "And that's the challenge of new technologies. Where are my guarantees?"


Ilan Levin says too often utilities are more worried about profits than pollution. Levin is with the Washington, D.C.-based Environmental Integrity Project, which recently released a list of the dirtiest power plants in the U.S.

Levine says historically, power plants have not reduced pollution emissions until forced to do so by government regulation.

"And even though utility companies might moan and gripe about the regulations that are imposed on them, time and again whenever a regulation has come down on this industry they've done just fine," says Levin. "The investments in technologies are there, the research is there. The will may not be there yet, but hopefully that's changing."

North Dakota coal country
North Dakota has some of the cleanest air in the country, but environmentalists say air quality is worsening in areas around power plants.
MPR Photo/Dan Gunderson

Environmental groups say the cheap electricity utilities say coal provides isn't so cheap if you count the hidden costs. Wade Schaefer with the Sierra Club says air pollution is responsible for thousands of deaths and illnesses each year.

Some studies suggest particulate pollution from power plants kills more that 20,000 people each year, and causes tens of thousands of cases of asthma and heart disease.

"They talk about providing cheap energy. But no one is saying you can have cheap energy, but you have to take asthma or retardation from mercury poisoning," says Schaefer. "So the energy industry is sort of disingenuous when they talk about providing cheap energy and not taking into account the health problems that come along with that."

Schaefer says power companies could clean up their smokestacks with technology that's already available.

The Energy and Environmental Research Center leads a variety of projects on air pollution at the Grand Forks research center. Associate Director Tom Erickson says it's technically possible to build a very clean coal-fired power plant.

"You could design a coal combustion facility to be zero-emission, or very near zero-emission today. The consumer couldn't afford to buy the electricity from that system, but we could afford to build it," says Erickson. "We just need these challenges and obstacles -- with the economics primarily, and some technical ones -- to be overcome, for that to come true."

Erickson says the economy is so dependent on cheap electricity, that government regulations are designed to ensure a continued supply of cheap power.


The EERC is working on two pollutants in the spotlight now -- mercury, which damages brain development; and carbon dioxide, which is thought to contibute to global warming.

pollution lab
Small power plant models allow EERC scientists to test pollution control ideas in a lab before spending millions to try them on a power plant.
MPR Photo/Dan Gunderson

The EPA says power plants emit about 50 tons of mercury each year, and power plants currently remove an estimated 25 tons from power plant exhaust. The federal government says mercury emissions must be reduced by 30 percent, but some states are requiring a 90 percent reduction.

Minnesota, for example, plans to reduce mercury emissions from power plants by 70 percent by 2014. But Minnesota officials say 90 percent of the mercury pollution in the state comes from smokestacks in other states. That's another challenge of air pollution. The effects are often felt far from the source.

Tom Erickson says mercury is a challenge because it's present in such small amounts that it's difficult to even accurately measure in the power plant exhaust.

"If you filled the Houston Astrodome, it would fill with 30 billion ping pong balls. Only 30 of those ping pong balls out of 30 billion would actually be mercury. That's how small an amount of mercury we're talking about," says Erickson.

But even that small amount adds up to thousands of pounds of mercury released into the atmosphere each year. Scientists at the EERC estimate it costs between $5,000 and $30,000 to remove one pound of mercury from a coal-fired power plant exhaust.

Test truck
EERC brings this truck-mounted emission control unit to power plants to demonstrate the technology.
MPR Photo/Dan Gunderson

Scientists at the EERC say better and more affordable mercury control might be available in five years, if the technology proves itself in the real world of massive smokestacks.

It may take longer to find what's considered an affordable solution for carbon dioxide, which many scientists link to global warming.

"If we want a revolutionary technology for C02, one that we would deploy at all coal combustion plants, we're looking at a long range solution, something like a decade," says Erickson.

Again, it's a case where today's technology could remove CO2 from power plant smokestacks, but industry says it would be too expensive.

Another question is what to do with the carbon dioxide after it's removed from the exhaust gas. Researchers are looking at ways to store the CO2 in abandoned underground mines, or inject it into old oil wells to increase the flow of oil. But experts say there are still many questions about what will happen in the future to CO2 stored underground.

Many in the coal industry admit coal-burning power plants are destined be become an industry dinosaur. They expect that 20 years from now there will be fewer power plant smokestacks belching pollution.

Those plants might be replaced with plants that turn coal into natural gas or hydrogen, instead of burning the inefficient, dirty coal.

Scientists say those coal gasification plants are the best hope for reducing pollution created by turning coal into energy.