UNION BRIDGE -- Burning tires as a fuel in cement kilns can be done safely and without creating toxic emissions, two experts said.
The practice -- which Lehigh Portland Cement Co. hopes to start next summer -- provides a cheap fuel and is an ideal way to dispose of the 4.5 million used tires generated in Maryland every year, proponents and state officials said.
Lehigh announced Thursday it will apply to the state this week to burn 2 million tires a year in its four kilns to reduce fuel costs.
The company hopes to replace 18 percent to 20 percent of its fuel with tires, plant manager David H. Roush said.
Tires burn cleaner than coal -- Lehigh's primary fuel -- because they have less sulfur, said Larry L. Gasner, an associate professor of chemical engineering at the University of Maryland at College Park who has studied combustion and cement manufacturing.
A kiln is a good place to burn tires because the temperature is high and the burning time long, he said.
Edward W. Kleppinger, a Washington environmental consultant who opposes burning hazardous wastes in cement kilns, said burning tires in kilns is safe if done properly.
"The issue is not so much the tire itself, but how it's burned," he said.
The method Lehigh proposes to use -- injecting whole tires in the middle of the kiln where the temperature is 1,800 degrees -- should work well, said an engineer with the Virginia Air Pollution Control Office who has overseen a similar project.
"The emissions do not appear worse to the eyes or nose," said Ray Goetz, a permit engineer involved in tests of the process at Roanoke Cement Co., a Lehigh competitor.
Tests at that company showed an increase in carbon monoxide emissions when tires were burned, but the emissions were not at dangerous level, he said.
Tests also showed an increase in particulate matter emissions, but the emissions could not be seen or smelled, he said.
Heavy metal emissions did not increase when tires were burned, Mr. Goetz added.
Roanoke Cement injected the tires at one end of the kiln where the temperature was 1,700 degrees, he said. Injecting the tires in the middle of the kiln where the temperature is higher probably would not result in an increase in carbon monoxide emissions, he said.
Carbon monoxide is an indicator of incomplete combustion and is dangerous if concentrated in high levels, such as in urban areas where it is generated by traffic, said Donald L. Shepherd, regional director of the Virginia Air Pollution Control Office in Roanoke.
In Maryland, Essroc Materials Inc. in Lime Kiln, Frederick County, received a permit last month from the state to burn tires.
Michael Sullivan, a spokesman for the Department of the Environment, said the company demonstrated in tests that it could burn tires and comply with emission regulations.
Essroc plant manager Bruce E. Ballinger said the company injected the tires in the middle of the kiln where the temperature was 2,000 degrees and detected a slight rise in carbon monoxide.
Lehigh is hoping to participate in a tire-recycling program sponsored by Maryland Environmental Service, a quasi-public agency under the state Department of Natural Resources.
Legislation passed last year requires the state to recycle tires. In February, the state mandated a $1 fee be levied on the sale of all new tires to help pay for the program.
Beth S. Schomburg, assistant to the MES director, said the state will review Lehigh's application and others it receives and decide in November which companies will participate in the state program.
MES then will establish a system to collect and distribute tires, she said.
There are 10 million to 15 million used tires stockpiled in the state now, she noted.
Lehigh, which produces 1 million tons of cement a year, plans to spend $2 million to install the necessary equipment to burn tires and will store only a five-day supply of clean, dry tires to eliminate problems with mosquitoes, Mr. Roush said.
Elizabeth H. Mikols, manager of environmental affairs at Lehigh's corporate headquarters in Allentown, Pa., said Lehigh plants in Germany have been burning tires as fuel for 15 years.
"We don't want to take on a project to solve one environmental problem and then create others," she said.
Area resident Julian S. Stein Jr., a leader in Residents for a Healthier Union Bridge Area, said the group is investigating the proposal.