The first of what could eventually be more than 2 million tires a year were burned by Lehigh Portland Cement Co. this week as the Union Bridge plant began testing its $1.5 million tires-as-fuel project.
In the works for two years, the project is expected to allow Lehigh to reduce its use of coal by as much as 18 percent, company officials have said.
It eventually would involve four cement kilns powered by the heat generated from the burning tires.
If successful, this week's testing would lead to the completion of three more cement kilns next year that can be powered by burning tires, officials said.
Tires will be burned in the rotary kilns -- welded steel shells 400 feet long and 11 feet in diameter.
Now powered by pulverized coal and waste oil, the rotating kilns melt the raw material used to make cement.
The temperature inside the kiln ranges from 1,000 to 3,000 degrees Fahrenheit.
The burning will occur rapidly, and, company officials insist, leave no smoke or odor because of excess oxygen and high temperatures.
With all four kilns burning tires, the company expects to burn 2 million to 2.5 million tires a year.
The company has declined to say how much it would save in fuel costs by using the tires.
However, at public hearings two years ago, experts testified that it was cheaper and cleaner than oil or coal.
Only one company in Maryland -- Essroc Materials in Lime Kiln, Frederick County -- burns tires.
Stack tests there have shown that burning tires creates less sulfur dioxide and nitrogen dioxide emissions and slightly more carbon monoxide emissions than burning coal, according to the Maryland Department of the Environment.
Burning one automobile tire is equivalent to burning 2.5 gallons of oil, specialists say.
Tires burn cleaner than coal because they have less sulfur.
Lehigh makes 1 million tons of cement a year in Union Bridge, using 400 to 500 tons of coal a day.
Lehigh will acquire the tires from a variety of sources, including Carroll County collection facilities and private tire dealers.
Lehigh officials hope the tires will be provided for free to the company.
Lehigh also expects to collect a small tipping fee from the tire suppliers.
Carroll County now sends up to 4,000 tires a month to the Essroc plant.
The county pays the company 50 cents a tire, or half of the $1-a-tire disposal fee the county collects.
"The tires have value as fuel, and we are able to dispose of them, so they don't sit in landfills," said John F. Curran Jr., Carroll County's solid waste special projects coordinator.
Lehigh began working on its tire-burning project more than two years ago.
After securing state permits to burn, haul and store tires, the project was delayed when another company filed a lawsuit against Lehigh for infringement of patent rights on its tire injection system.
The lawsuit was settled this year.