This week’s column assumes that the reader is familiar with the fact that Duke Energy has been tasked with closing or upgrading its coal ash lagoons across the state of North Carolina following a massive coal ash spill into the Dan River near to Eden, NC. If you are not familiar with the background, I recommend you read my previous column, A Tale of Two Spills, before proceeding.
When you burn coal to make electricity, just like burning wood in a fireplace, some ash is left behind. Coal ash is hazardous since it contains a number of toxic, heavy metals such as lead, arsenic, and mercury. As a result, human beings and other animals are well advised to not ingest coal ash or, even more importantly, breathe it into their lungs. Since the greatest health risk from coal ash arises from breathing it in, coal companies immerse the ash in water in on-site lagoons to keep coal ash dust out of the air.
While it is possible to recycle coal ash into concrete and several other building products, it is not an economically attractive alternative. Therefore, electric power companies all across the country have been accumulating a staggering amount of coal ash – estimates range in the trillions of tons – over the past half a century or so. Duke Energy has 108 million tons of coal ash stored in 32 lagoons across North Carolina. Since coal-fired power plants are nearly always next to rivers and lakes, so are these lagoons. In an attempt to prevent more incidents like the Dan River spill, Duke Energy has been ordered to develop a plan to remove the coal ash from the lagoons and store it “dry” in lined landfills far from rivers or lakes. Every time I read that, I am struck with the question of, “What do they mean by dry?” Let me explain why that is an important question starting with a thought experiment which will help to outline the key issues.
Let’s say that you are at the beach and have a bucket of sand with a layer of water above it and I assigned you the task of drying the sand in the most time and energy efficient manner possible. First, you should decant off the water above the sand. That’s easy to do and not energy intensive. Next you could get more water out of the sand by squeezing it. For example, if you had another bucket of the same size, you could press down on the wet sand and this would coax out some additional water that you could then decant off. At this point, you would be left with a wet cake of sand of which water would constitute approximately 25% of the total weight.
In order to remove the rest of the water you would need to evaporate it. Therefore, you will need to apply heat, a substantial amount, and you will need to mix the sand during the process. If you do not mix the sand, the water in the interior of the cake would take a very long time to diffuse the surface of the cake were it can evaporate and escape. Your possible heat sources are the sun, provided it is not cloudy or night time, or you could build a fire. As you have likely inferred, the point of this thought exercise is to illustrate that removing water trapped within cake of small particles is not a simple task.
A lagoon of coal ash shares has quite a bit in common with a bucket of wet sand. At the bottom of the lagoon is a sludge of wet coal ash particles beneath layer of water. The water can be decanted off without difficulty. Just as was the case with the sand, more water could be removed from the coal ash sludge by squeezing it. There are many known technologies that could be used such as a belt press. However, running tens of millions of tons of wet coal ash cake through a belt press would take a very, very long time. So perhaps Duke Energy would choose to skip this step.
I was unable to find physical property data for coal ash, so I need to make an assumption before proceeding. Based on similar materials, I estimate that pressing coal ash sludge would create a wet cake containing approximately 20% water. Therefore, the 108 million tons of coal ash in Duke Energy’s lagoons would correspond to 135 million tons of wet cake containing 27 million tons of water.
So this brings us to my question. Is this wet cake of coal ash what Duke Energy is describing as dry? To my engineering mindset, the answer should be “no.” However, I suspect this is what Duke Energy is describing as dry coal ash and, despite my quibbles with word usage, I hope this what they mean. There are two important reasons for this. The first is energy consumption. Evaporating 27 million tons of water to truly dry the coal ash would require 53,000,000,000,000 BTUs of energy. To give you an idea of how much that is, it is equal to the energy required to provide electricity to 1.4 million average American households for a year. The second problem is dust. If Duke Energy thoroughly dried the ash, especially since you have to mix it to get it to dry, they would generate a lot of dust. The best way to control the resulting dust would be to spray it with water, which would be an absolutely ridiculous thing to do after just drying it. So what are they really doing?
I have been trying to figure this out for a while. Duke Energy has a section on its website about its coal ash clean up program complete with several videos. However, the question of what constitutes dry coal ash is not addressed. There is some footage of a bulldozer scooping up some coal ash from a lagoon that has no standing water. No dust is begin generated by the bulldozer with suggests that the operator is scooping up wet cake rather than dry ash, which suggests that my theory is correct. If so, then Duke Energy is being prudent in not expending the energy necessary to dry the ash and safety conscious in not generating a risk of dust exposure. However, if this is true, they are shying away from discussing the science underlying this effort. I’m not sure why that is but, not to worry, Common Science® is not similarly shy.
Jeff Danner spoke with Aaron Keck on WCHL Monday.
Have a comment or question? Use the interface below or send me an email to firstname.lastname@example.org. Think that this column includes important points that others should consider? Share a link to this column on Facebook or Twitter. Want more Common Science? Follow me on Twitter on @Commonscience.http://chapelboro.com/columns/common-science/coal-ash-how-dry-is-dry/
Chatham County officials have reached an agreement with Duke Energy on parameters of storing coal ash at a clay mine in the county.
A deal was struck between the county and the energy giant after weeks of negotiations, according to officials.
Chatham County Manager Charlie Horne says the county’s focus was getting the best arrangement it could with Duke.
“Given that, no matter what we do, we’re likely going to get coal ash,” he says, “what is the best deal, if you will, we can get from Duke Energy to do other things potentially in Chatham County.”
Duke Spokesperson Jeff Brooks says the company is happy both sides were able to reach an accord.
“We’re very pleased to have reached an agreement with local leaders that will provide positive benefits, we believe, to the people of Chatham County,” he says. “Duke Energy is very committed to being responsible and transparent as we move forward with our work at the Birckhaven mine and ensuring that the work that we do is done safely and with a focus on protecting the environment.”
Horne says the agreement puts forward the parameters of the coal ash that can be moved to Chatham County.
“The agreement provides for a limit of 12 million tons of coal ash disposal at the Brickhaven site in Moncure,” he says. “In return for that, we will get $1.50 per ton for that disposal up to 12 million tons.”
Lee County officials agreed to a similar deal with Duke Energy earlier this year to store coal ash.
It came to this stage of seeming inevitability for the county after the state Department of Environment and Natural Resources granted Duke the necessary permits to dispose of coal ash in the pits.
Brooks says the state is the ultimate rule maker in this scenario, but Duke would prefer to operate with cooperation of local government.
“Certainly the state law directs how we operate and how we move forward with this project, but we recognize that there’s an impact to the local community,” he says. “We recognize that, just from an operational standpoint, this will be something ongoing for several years in Chatham County.
“And we wanted to be fair to the local community. We wanted to find a solution that could provide positive benefits to the people of Chatham County.”
The ash will be stored dry, rather than in the lagoons it is currently stored in across the Tar Heel state.
The pits will be lined before the ash is placed into the pit and another layer of lining will be placed over the coal ash once it is in place, according to Duke.
Horne says the county is pleased no additional ash will be brought to the site of the Cape Fear Plant.
“The Cape Fear site, which was the old power plant, Duke Energy also agreed that there will be no coal ash stored there other than what’s already on the site,” he says. “We think that’s a plus.”
As part of the Coal Ash Management Act of 2014, Duke has to move coal ash from lagoons at four high-risk sites across North Carolina by 2019. Duke must move all of the coal ash from the 10 remaining sites by 2029.
Brooks says progress has been preliminary up to this point.
“We’re actually finalizing a lot of those plans,” he says. “We’ve announced some of them, obviously. We’re beginning the process of siting land fills at some of our plants that will be used for storing ash.
“We’ve begun moving ash from our Riverbend station to a location in Georgia that is accepting that material. And I think that you’re going to see over the next few months a lot of activity, a lot of new announcements on plans and other work that’s being done.”
Brooks says the nation’s largest electric utility is focused on meeting the deadlines laid out by the state.
“We believe we can meet the timelines. We are committed to complying with the law,” he says. “It’s going to be a herculean task, and it’s going to take a lot of work from many dedicated teams that are working throughout the company.
“But right now our focus is on meeting the requirements of the law and doing that in a responsible way.”
Before any coal ash can be moved to the pits in Chatham and Lee Counties, Duke Energy still needs approval from the federal government and the Army Corps of Engineers.
Brooks says that Duke is hopeful that late this summer or early this fall it will be able to begin work at the site in Chatham County.
County officials say the $18 million Duke will be providing the county in exchange for the storage will be used to monitor the environmental risks around the site. Commissioners have also asked for baseline testing to be done of water sources around the pits.http://chapelboro.com/news/local-government/chatham-county-officials-agree-to-deal-with-duke-energy-on-coal-ash/
Google, Apple and Facebook sent a letter to North Carolina legislators urging them not to change the state’s renewable energy laws. State representatives are considering a bill that green energy advocates say would negatively impact the renewable energy sector.
The tech giants’ letter urges legislators not to adopt House Bill 332. The proposed legislation would make significant changes to the state’s Renewable Energy Portfolio Standard (REPS).
The REPS requires utility companies to buy a certain percentage of their energy from renewable sources, such as solar or wind power. The REPS also requires utilities to increase the percentage of clean energy they buy over time. Allison Eckley of the North Carolina Sustainable Energy Association (NCSEA) says the REPS has been key for the growth of green energy companies in North Carolina, and to keeping rates down for consumers.
“We’ve already seen the downward pressure on electric bills that these policies have had,” Eckley said.
House Bill 332 wouldn’t get rid of the REPS, but it would freeze the REPS requirement at its current 6 percent. Google, Apple and Facebook expressed concern in last week’s letter to legislators that limiting the REPS would hold back the growth of North Carolina’s renewable energy sector. The three companies employ 200 people in North Carolina and have invested $2.7 billion in the state. More than half of their investments are in the renewable energy sector, according to a statement from NCSEA.
“They’ve been following the policy developments here because they consider clean energy as a supplier to that power as a priority. And that’s part of the reason, as they say in the letter, that they selected North Carolina instead of other states in the Southeast that also have cheaper electricity,” Eckley said.
House Bill 332 is co-sponsored by Rep. Mike Hager, a former Duke Energy employee. He and other proponents of House Bill 332 say the REPS unfairly support the renewable energy industry over other sectors. Becki Gray, from the Raleigh-based conservative think-tank, the John Locke Foundation, agrees.
“This mandate, these special favors that are granted to the solar industry at the expense of taxpayers is not good policy. It doesn’t lead to good economic growth,” Gray said.
Gray argues the opposite of Google, Facebook and Apple when it comes to the REPS’ downward pressure on rates.
“The studies that we’ve seen show that that is not true, that the costs increase with the requirement that a certain percentage of your energy has to come from more expensive sources,” she said.
House Bill 332 is being debated in the Senate. For now, the one thing both sides can agree on is the need for more research on the REPS’ economic impact.http://chapelboro.com/news/state-government/google-apple-facebook-send-letter-to-nc-legislators/
Coal ash could be coming to Chatham and Lee Counties, as Duke Energy looks to use old clay mines for disposal.
The N.C. Department of Environment and Natural Resources received a pair of applications last week from Green Meadow LLC, a company seeking permission to move coal ash stored at power facilities to fill in open-pit clay mines.
One mine is in Chatham County near Moncure, the other is in Lee County near Sanford.
The permits would allow Duke Energy to relocate coal ash from power plants in Mount Holly and Wilmington and use it to fill the open pits after installing liners to prevent groundwater contamination.
Green Meadow LLC hopes to begin work on the structural fill projects at both mine sites in early 2015.
However, a public hearing must be held first, and the permits must be reviewed by the Division of Waste Management before work can begin.
In addition, the Environmental Protection Agency will likely roll out new federal guidelines for coal ash disposal in December, which could have an impact on the application.
Ultimately, Duke Energy hopes to relocate 3 million tons of coal ash to Lee and Chatham counties.http://chapelboro.com/news/safety/duke-energy-hopes-send-coal-ash-chatham-lee-counties/
Chapel Hill Police Sergeant Bryan Walker says local businesses have been the target of a recent phone scam.
“Businesses are receiving a telephone call from someone that purports to be from Duke Energy. The way the scam works, the person calls the business and tells whomever answers the phone that they’re late on payment and unless they immediately make a payment, the power will be turned off.”
The scammers threaten to cut off electricity within the hour and demand the victims purchase a pre-paid money card to transfer payment.
Walker says this makes the transaction hard to track once the victim realizes it’s a scam.
The high pressure tactics have proven successful, and they’ve cost some victims hundreds of dollars. In at least one case, the scammers accepted a fraudulent payment, then turned around and asked for more.
“Once the person paid $400, they were immediately told, ‘Well, we didn’t tell you about these other fees, you owe us another $300.’ So if they get one amount of money out of you, they may try to get more immediately.”
Recently, a business owner on Elliot Road got one of these types of calls. She listened to the scammer’s pitch, but hung up and called Duke Energy for confirmation. Walker says if you have doubts, it’s important to hang up and call the utility directly to make sure you’re talking to a real Duke Energy representative.
“The scammers have gotten to the point where they’re a little more sophisticated and if you ask, ‘May I call you back?’, they may say, ‘Absolutely, here’s the number,’ and give you a number that allows them to be ready for your call.”
According to Duke Energy’s website, customers who are behind on payment will receive multiple notices of delinquency over the course of several weeks, never just a single phone call. The power company has set up a webpage describing some of the recent phone scams and offering tips to thwart them.
If you have received any suspicious phone calls, you should alert local police and Duke Energy.
Duke Energy plans to charge residential customers more in order to establish new renewable energy sources, such as solar panels, across North Carolina.
Spokesperson for Duke Energy, Lisa Parrish, explains the changes and how much more customers may be paying.
“Right now, the average residential customer for Duke Energy Carolina is using about 1000 kilowatt hours of electricity, pays about 4 cents a month to comply with the new renewable energy portfolio standards,” says Parrish. “The new writer asks them to pay 39 cents, so that is an increase of 35 cents. Duke Energy progress customers using 1000 kilowatt hours, they are currently paying 20 cents, and that changes to 83 cents.”
She says that these new charges must be made in order to comply with new North Carolina laws that dictate energy costs and where they must be placed for customers.
“Think about it like this: you divide the pie, the renewable energy pie, into three pieces. The sizes of those pieces are dictated by the North Carolina energy law,” says Parrish. “So, more than half the pie, about 59%, is paid for by residential customers, 36% is paid for by commercial customers, and about 5% is paid for by industrial customers. Each of these slices is in proportion to the cost caps set by the North Carolina energy law. The legislation tells us what we can charge these customer classes, and tells us they must be in proportion to the cost.”
Awaiting permission from the Utilities Commission, these new charges are set to go into effect in December of this year.http://chapelboro.com/news/state-news/duke-energy-raises-prices-renewable-energy/
Despite the high temperatures across North Carolina, the heat may not pose much of a problem for Duke Energy’s power grids.
Spokesperson for Duke Energy, Jeff Brooks, says that because of the sweltering heat inciting a greater usage of air conditioning, Duke Energy is certainly prepared for the increasing demand for cool airflow.
“We don’t anticipate any problems with meeting customer demand during this time,” says Brooks. “We know it’s very hot, but our grid is ready to respond, and we take steps to ensure that our electric grid is able to respond to customer demand, even when it reaches the high levels as we’re seeing during these hot days.”
Brooks also says that there are a myriad of ways for Duke Energy customers to take steps to still keep their electricity bills low when fighting the heat.
“We want our customers to be comfortable, and certainly we’re going to provide the electricity they need to enjoy their lives,” says Brooks, “but from a bill standpoint, customers can take steps to keep their energy costs lower during periods of high usage.”
Brooks says he suggests taking actions such as setting air conditioning to the highest comfortable setting and to turn it up a few degrees if you will be away from the house most of the day, making sure air filters are clean, using ceiling fans or portable fans, keeping blinds closed, and general maintenance on units. He also says that Duke Energy offers programs for customers to voluntarily decrease their energy usage on days when energy demands are higher to receive credit on their bills for participating.
When it comes to how the heat will affect the machinery of the grid itself, Brooks says that customers can rest assured that they will not have to worry about any technical difficulties.
“The electric grid is a machine, like any other machine, and temperature does have an impact on the way a machine works,” says Brooks, “but we’re not expecting anything that would cause any reliability issues at all; we’re going to be able to meet customer demand during this period.”http://chapelboro.com/news/state-news/duke-energy-grid-will-beat-heat/
It’s agreed that Duke Energy needs to stop the contamination of waterways and areas surrounding its 33 unlined coal ash ponds at 14 coal-fired power plants located across North Carolina. But state officials, activists and company leaders are at odds over the best way to address the problem.
In the wake of the massive spill into the Dan River in February, environmental groups are demanding that the nation’s largest utility remove the more than 100 million tons of hazardous coal ash away from rivers and lakes.
This would entail drying the coal ash, which contains toxic substance such as lead, arsenic and mercury, according to WCHL’s resident science expert and engineer Jeff Danner.
Duke Energy representatives told a legislative committee last week that removing all of the coal ash away from the state’s rivers and lakes would take decades and cost up to $10 billion, with the company’s customers likely to pay for the majority of the cleanup, the Associated Press reported.
“If it were just the time and the expense involved, I would say, ‘Just go ahead and get on with it,’ but I think it is important to understand that the excavation and transportation process would be an extraordinarily dangerous thing to attempt,” Danner said.
Danner, who has been following the fallout from the coal ash spill, said that from an engineering standpoint, he believes the safest way to deal with the coal ash is to continue to store it on-site, but in a different manner, without having to dry it.
Drying coal ash ponds to remove the waste would be dangerous if it were to become uncontained and dispersed.
Danner suggested incorporating the coal ash into solid blocks of concrete as a safer form of long-term storage.
He said that attempting to dry and move the coal ash waste could prove to be disastrous and result in accidents associated with these types of non-routine procedures, he said.
“In order to keep it on-site and keep it from blowing away in the wind, it is kept under water,” he said. “When you hear ‘coal ash pond,’ [it means] that they are keeping it under the water so that it doesn’t blow away.”
Inhaling coal ash, he said, obviously leads to getting the toxic substance in your lungs which can cause immediate health problems and can lead to cancer.
If the coal ash were to be hauled away in massive amounts to a central lined-landfill, Danner said the risk would be too high. Having to excavate the collection ponds and relocating the massive amounts of coal ash that have accumulated over the years versus disposing of it as it accrued are very different matters.
“I think if you want to say what should have happened in all these years from the very beginning is that it would have been manageable to store this waste and take it off-site in small increments as it was generated over the last couple of decades,” Danner said.
Duke Energy officials told lawmakers last week that they proposed to excavate the coal ash at only three of its power plants in an effort to be more cost efficient. For the remaining plants, they would dry the ash and cover it with giant tarps topped with soil.
Danner said that this method would not be a viable long-term solution either and that the tarps would corrode over time.
The most environmentally friendly and least dangerous threat to human health, he said, could be done without having to dry the coal ash.
From a broader perspective, Danner said that Duke Energy could fund studies to examine the larger issue of coal ash ponds and find better solutions for how to store it.http://chapelboro.com/news/state-news/cleaning-coal-ash-whats-best-way/
The Duke Energy coal ash facility fallout continues—this time at a Chatham County plant located about 25 miles south of Chapel Hill. State environmental regulators are now investigating whether the utility has been pumping contaminated wastewater into the Cape Fear River.
Jamie Kritzer, spokesman for the N.C. Department of Environment and Natural Resources, said that state inspectors observed on March 11 that Duke Energy workers had possibly pumped water from two coal ash ponds located at the Cape Fear Plant in Moncure, which was closed in 2012.
The pumps were attached to hoses that carried water from the coal ash ponds into an internal canal.
The canal is supposed to discharge only treated wastewater from the coal ash ponds.
The concern is whether contaminated water was also released into the canal, which flows into an unnamed tributary that feeds the Cape Fear River, a drinking water source for several cities. Coal ash contains toxic chemicals such as arsenic, mercury and lead.
“The utility told us that they were conducting routine maintenance,” Kritzer said. “Certainly some routine maintenance is allowed under their wastewater discharge permit, but discharge of untreated wastewater could be a violation of that permit. That is what we are looking into right now.”
Kritzer said DENR discovered the potentially illegal pumping during a planned investigation of the plant.
This was part of a state-wide effort by DENR to conduct detailed inspections of all 14 Duke Energy facilities with coal ash impoundments.
The investigation was precipitated by the February coal ash spill at a Duke Energy plant in Eden during which at least 30,000 tons of pollutant were released into the Dan River.
Kritzer said DENR officials are expected to make a decision later this week about whether Duke Energy violated the discharge permit at the Cape Fear Plant.
“There is the potential we could issue notices of violation. Those could carry with them fines and penalties that could be fairly stiff,” Kritzer said.
The Waterkeeper Alliance, an environmental group, flew a plane over Duke Energy’s Cape Fear River plant on March 10 and photographed the two pumps drawing water from the two coal ash ponds. Those photos were released to the media.
DENR maintains that the state agency’s inspection discovery was independent of Waterkeeper Alliance’s investigation.
On Tuesday, a federal grand jury convened as part of a widening criminal investigation triggered by the coal ash spill in Eden, the Associated Press reported. The jury will examine whether state regulators, DENR officials included, helped shield Duke Energy regarding its negligence.http://chapelboro.com/news/state-news/duke-energy-chatham-spill/
A new poll finds that almost 80 percent of North Carolinians think Duke Energy alone should pay for the clean-up efforts from the recent coal ash spill on the Dan River. Earlier this month, the nation’s largest utility decided that its customers would bear the burden through increased rates.
Tom Jensen, of the left-leaning Public Policy Polling in Raleigh, says the numbers also show bipartisan agreement that Duke Energy should pay for the clean-up.
“We find that 81 percent of Independents, 79 percent of Republicans, and 79 percent of Democrats alike think that it isn’t something that should be passed on to customers. It isn’t something that should be passed on to taxpayers,” Jensen says. “They all feel with regard to no party divide at all that it should be Duke Energy’s responsibility to clean this up.”
On February 2, an old stormwater pipe collapsed at Duke Energy’s plant in Eden on the Dan River. It has been estimated that the spill dumped at least 30,000 tons of pollutant into the river, coating approximately 70 miles. Coal ash contains toxic contaminants such as arsenic, mercury and lead.
Governor Pat McCrory, who worked for Duke Energy for more than 30 years, told reporters Monday that his main concern is cleaning up the spill and then finding a long-term solution for the more than 30 coal ash ponds located in North Carolina.
When it comes to how the Republican leader has handled the spill, the poll found a greater partisan divide. Jensen says Republicans think McCrory has done an “all right job,” whereas Democrats think he has done a poor job.
Overall, only 30 percent of voters give him good marks for how he has responded to the spill compared to 44 percent who disapprove. That is worse than his overall approval numbers, Jensen explains. Forty-seven percent of voters disapprove of the job McCrory is doing, compared to forty percent of who voters approve.
“And I definitely think that what your are seeing there with the coal ash numbers being worse than his overall numbers is some feeling that maybe he is not being tough with Duke Energy. I certainly think that a part of that could be his former employment there.”
Jensen says that not surprisingly, the coal ash spill has had a negative impact on Duke Energy’s image.
“Only 26 percent of voters have a favorable opinion of the company [compared to] 52 percent with an unfavorable opinion,” he says.
To see the full results of the poll, which was conducted between March 6-9, click here.http://chapelboro.com/news/state-news/poll-voters-think-duke-energy-pay-coal-ash-clean-customers/