Imagine a coal-fired power plant that’s humming away smack dab in the middle of a small town. Its neighbors? A hospital, senior living facilities and a library. That’s the kind of power plant that Melanie McCoy manages, complete with all its peculiar problems and positives, for Wyandotte Municipal Services. The 70 MW plant sits on the Detroit River about 11 miles south of the Motor City. McCoy talked with us about the plant’s special issues, the great people she works with in Wyandotte, Mich., (pop. 28,000), and what she would do if someone gave her a blank check and said, “Buy whatever you want for your coal plant, Melanie.”
Tell us about the power plant’s unique location.
It’s bounded by the Detroit River, Bishop Park, which has a playground next to it, and the Henry Ford Hospital. The library’s right across the street on the front side of the plant and there’s some senior housing in this area, too. We’re right in the middle of town.
There’s no railroad to ship coal in, is there?
Everything comes in by barge. In the winter we don’t get coal coming in on the boats because the lakes are frozen, so we have to unload our last boat in December. That’s when they start closing up the locks and putting all the boats away. We have to get a big stockpile of coal at the plant and we also unload one boat down the road at a facility where there’s a bulk storage area. We go through our coal pile at the plant until the spring and then we start trucking that coal down. It holds us over until the first boat comes in when shipping season starts again.
What else is trucked in?
The shredded tires that we burn in addition to coal. There’s a factory here in Wyandotte where they shred the tires and their warehouse is just a couple of miles away.
Is that a program you started?
Click here to enlarge image
No- I’ve only been here a year and two months, so I’ve benefited from everything that everyone else started before me! The tire program started about five years ago, I think, and two years ago they increased the percentage that they were allowed to burn, because they had been limited to 15 percent. They increased our permit to 50 percent but we haven’t been able to get there because of boiler issues-more ash handling issues-but at least the permit is there.
Ash from tires can’t be recycled, correct?
At this point, that’s right, for a couple of reasons. We have high unburned carbon, which is our fault from a combustion standpoint-that’s a little bit “the nature of the beast”-and then there are some metals in it because of the wire and also there’s some zinc in there.
Can you tell us about your plant’s fuel mix?
We have two boilers here that we operate most of the time. One boiler burns the coal and shredded tires. That’s a CFB boiler, a fluidized bed boiler. The other one is the pulverized coal unit and that one is just pure coal. We can sell ash from it, but again, we have a lot of unburned carbon in that too, and that’s one of the things we’re working on, trying to reduce our unburned carbon so we can sell more of the ash. The third boiler is gas and we haven’t run that boiler in several years.
In your location, emissions are a sensitive subject, aren’t they?
The CFB has a bag house for the particulate and with a CFB, NOx is lower because it’s lower temperature and SO2 is lower because limestone’s going in there. Shredded tires have next to no mercury in them and they’re lower ash so they’re actually better to burn than coal. They do have sulfur in them, but you’re burning the limestone with it so you’re capturing it. The other unit has a hot side precipitator.
In terms of our local neighborhood, the emissions that we are troubled by are coal dust and ash, not necessarily stack emissions. The parking lot for the hospital, for instance, comes right up next to our ash silo. Unloading ash at any power plant is ugly; it’s one of those systems that are never pristine-that’s the value of having a power plant in the middle of nowhere. But it’s an irritant, not a hazardous issue.
Have you had coal pile fires?
This year we’ve been lucky, we haven’t had any major coal pile fires, just the normal ones, but one started my first month here. Talk about trial by fire!
Typically, we negotiate with our coal consultant to get different blends of coal. We’ve tried different blends and types to take advantage of what we can burn and still get at a good price. That year we were debating whether to buy more power than we were going to generate because the coal prices were really high, but in the end we purchased coal. Because of our timing, a lot of the coal was already taken and the prices were high so we went with a higher PRB [Powder River Basin] blend than we ever had before. But we have a coal pile that can’t be compacted. Normally, when people are burning either 100 percent PRB or any kind of a blend of the PRB, the coal is unloaded and compacted so you don’t get a lot of air in there. But our pile is straight up and down and we can’t compact it so we started getting fires. It was horrendous from a safety standpoint, from a community standpoint-it meant calls to the fire department and we had to get rid of it. We had to get it into the boilers safely. You learn a lot from unintended consequences.
Do you usually go with long-term coal contracts?
We’re going two years now, where we were doing one-year contracts for the last several years. That gives us more options to look at the variety of fuels. This year, we’re burning 100 percent bituminous from the central Appalachian area and that’s good for us.
Does Wyandotte also purchase power?
Last year our peak was 65 MW. Since we don’t use that gas boiler we don’t get to 70 MW. The peak that we can generate if everything is going really well is 52 MW to 54 MW, so we do purchase power during peak days. We are able to sell a couple of megawatts on some days.
One of the disadvantages with these particular boilers, because of their size and the controls on them, is that we aren’t able to come down at night during the off-peak times as much as we’d like to.
So we started a new arrangement, one of the programs I walked into when I came here. We have a new steam line that we have just put in to BASF, which is our largest customer here in town. The steam line is for a small amount of process heat but more than anything it’s used for heating their big facilities here. Our big electric power days are in the summer, so in the winter time, we’re supplying steam, especially at night. It’s a perfect fit for us. The heavy loads are in the winter, when we have the excess power. And we’re also able to use an extraction to get that from the turbine, so we “use the steam twice.” It’s helped, I think, because BASF is now expanding and bringing in another facility, which is a real positive for employment here in Michigan.
If money was no issue, what would you do next at the plant?
I would modify that gas-fired boiler to be able to burn alternative fuels. Right behind that would be an upgrade of our environmental controls. Those are an issue for us going forward because we don’t have a scrubber on the pulverized coal unit. We’d put in a bag house and a scrubber on that unit. Then, I’d like to figure out how to sell our ash. There are companies that either do the ash reburn or separation so you can sell your ash, but unfortunately the payback’s not so great right now unless you’re in a state where disposal costs are really high. But at the same time, it’s just a good thing to do.
Wyandotte Municipal Services’ power plant is located in the middle of town, with a hospital and a playground near by. Coal is delivered by barge on the Detroit River.
Click here to enlarge image
Which alternative fuels are you thinking about?Wood chips or waste products from the furniture manufacturers. And there’s a possibility that a bio-diesel operation might be locating to this area, so we might be able to burn the glycerine, which is a by-product. What I don’t want to burn, but I know it would be good if we could, would be any of the municipal solid wastes or the sludge from the water treatment plants that they’re drying.
Coal is delivered by barge on the Detroit River until December, when the river freezes. Photos courtesy of Wyandotte Municipal Services.
Click here to enlarge image
What worries you most when you look at the next six months?All my worries are money. Because of fuel prices, we’ve been challenged recently and because of the small size of our units, we’re not as economical to generate as some of the larger units out there. Day to day, there are two things that worry me. First, as I mentioned, BASF is expanding so we’ll have to put in another substation to get them additional feeds and that’s a major undertaking on the T&D side. Second, our emissions at the power plant. I know we can comply through some fuel switching or minor operational changes or modifications and also by purchasing allowances, but I would like to be able to retrofit the boiler with some better controls so that we didn’t have to be so constrained.
What makes this job interesting?
I love the variety. I worked for 10 years at Detroit Edison before I came here and prior to that I was with Southern Energy, which became Mirant, so I’ve been at an IPP, too. When I worked at a bigger utility I was a plant manager, just worried about that plant. You didn’t work as a whole system. Here, on the muni side, I get involved in every single area, the coal purchases, the power purchases, and I get to learn about transmission and distribution-the substation and the transmission folks here are patiently educating me. And I love the people here-it’s that pride of ownership that comes from working at a muni. It’s impressive.
So you don’t have workforce issues?
We’ve been very lucky, but we’re not without issues. On the whole we have been fortunate to have good people here, but people are going to be leaving in the next several years and how are we going to replace them? We’re small, so we don’t have that depth in the organization to bring people in early.
Did you always want to be a plant manager?
The one thing I knew was that I didn’t want to work in an office and that I wanted to get dirty. I didn’t excel in English and literature-I was a lot better at math and science so I went into the engineering field. I started with building power plants then went into the operation.
And coal has been your focus?
Yes, since I saw the light and was able to escape from the nuclear world. I got into the operation and maintenance of the coal plants.
Is this your “dream” job?
I think so, I really do. I was happy where I was but this sounded too interesting to pass up. And I was lucky, because there were some really proactive people here before me.