Planning continues for Willmar Municipal Utilities power plant improvements
WILLMAR -- Willmar Municipal Utilities hopes to construct a building next to the power plant to store coal and eliminate dust and storm water runoff concerns. The project is among improvements, including new emission controls, being proposed for the plant.
The plant burns gas and coal to generate electricity and provide hot water for the central heating district. Coal is piled outdoors near the north side of the plant and is subject to storm water runoff and dust issues.
General Manager Bruce Gomm said the utility has been concerned about environmental issues associated with storing coal outdoors. He said engineering work has begun on this project. The facility will cover a portion of Pacific Avenue that was vacated by the City Council.
"Our intent is to construct a building over that pile so that we can control the climate and mitigate those issues,'' Gomm said.
The building will increase the supply on hand from one month to about four months. The larger supply will enable the utility to deal with temporary interruptions. One such interruption occurred last January when several carloads of wet coal arrived that could only be removed with much effort in large, frozen and unusable chunks.
The mines took back the coal.
These are the only mines, however, that can supply the type of coal that complies with Willmar's boiler restrictions. The boiler cannot burn coal that is above a certain level of sodium. The sodium condenses and corrodes the dust collector tubes.
"This again is one of the reasons why I am really pushing for the project because if we do the power plant upgrade, we will put a new dust collector in that won't have that issue,'' Gomm said. "With the upgrades, the utility will be able to buy coal from anywhere. Hopefully, if we have problems with one supplier, we can switch to another supplier on the go.''
All improvements are contingent upon approval of the utility's air quality permit by the Minnesota Pollution Control Agency. The utility is unable to modify the plant without having a permit in hand. Gomm said he's cautiously optimistic the utility will receive the permit this year.
"That will be a big accomplishment for us. It's something we've been working on for a couple of years now. It means a lot for us in the community to be able to ensure the viability of our power plant,'' he said.
The plant is currently limited by how much power it can produce on coal because the plant reaches what is called its opacity limit, which is the amount of particulate matter emitted into the atmosphere. The utility continuously monitors its emissions.
The unit is rated at about 17 megawatts on any type of fuel, but can't exceed 8 megawatts on coal without doing more work on emissions. A system called a bag house is being proposed to handle the problem.
Gomm said there were no pollution limits years ago when the boiler was installed.
"Like a lot of other coal plants of that era, they weren't the most environmentally friendly when they were first produced,'' he said. "But that was the technology of the time and we have since matured, I like to say, and we've learned how to make burning coal a cleaner and cleaner operation.''
Preliminary engineering continues on the biomass project using corn cobs as fuel. Cobs will help the utility comply with the state's renewable energy mandate of 25 percent of annual generation from renewable sources by 2025. Cobs will be stored in the new building.
Results from test burns in 2009 show cobs are very favorable. Some boiler retrofitting will be needed to burn cobs. If cob prices come in where officials expect, which is based on U.S. Department of Agriculture grants for farmers, the cost of generating power with cobs would be just slightly more than the cost with coal, said Gomm.
"We would want to do as much of that as we can,'' he said. "It is one of the reasons to help meet the renewable energy mandate, but the second is just to ensure the viability of the plant and to promote the community any way we can and being able to purchase fuel locally is, we feel, good for the local economy.''
The utility also continues doing as much preliminary engineering as possible on miscellaneous boiler upgrades and improvements.
The projects are budgeted at $10.5 million.
Gomm said the utility is proceeding with the project because the decision was made to keep the plant and generate power locally.
"We went through a period of time when the economics of having the plant here locally were a little bit questionable. The thing that really made it viable was having the heating district and the needs of the heating district. That really helped to get through a couple of leaner years,'' said Gomm.
"But since I've been here (the last four years) we've been looking at this and running the numbers on the finances and it's quite valuable to have that local generation resource right here.''