Scrap tires would be burned to fuel a Pueblo-area cement plant under plans proposed by the facility’s owner.
Incineration of tires is becoming a common practice in cement fabrication as a way to reduce the use of coal and natural gas.
The method also provides a partial solution to a major problem: how to deal with the 300 million car and truck tires discarded every year in the U.S.
But it also is creating concern among some Pueblo residents and environmentalists who fear that burning tires will produce odors and toxic emissions.
“It’s really like burning hazardous waste,” said Ross Vincent, chairman of the Rocky Mountain Sierra Club’s Pueblo-based regional arm. “We think fundamentally that it’s a bad idea.”
Not so, say officials of the plant’s Mexican owner, Grupo Cementos de Chihuahua and its Denver-based subsidiary, GCC of America.
Burning tires, they say, actually is cleaner than combustion of other fossil fuels and helps reduce landfill use.
Opponents and proponents cite studies and anecdotal information in support of their claims. Yet little peer-reviewed independent research exists for a business practice that has become prevalent only over the past decade.
GCC recently purchased for $2 million the Midway tire landfill south of Fountain as a potential source for the cement plant.
Officials of GCC said they have no immediate plans to burn tires, calling the idea a “medium-term project” that would involve filing for state and local zoning and air-quality permits.
The $300 million cement facility southeast of Pueblo began operations last year and has been using coal in conformance with existing permits.
During production, heat — temperatures of up to 2,800 degrees Fahrenheit — is needed to chemically transform limestone and other minerals into cement.
Coal, petroleum coke and natural gas have been the traditional fuels used in the process.
But today, about one-half of the approximately 100 cement plants in the U.S. have permits to burn “tire-derived fuel,” or TDF, according to the Portland Cement Association, an industry trade group.
“The cement industry is very proactive in its effort to reduce energy consumption, particularly fossil fuels,” said Enrique Escalante, president of GCC of America. “We understand the benefits to both the economy and the environment of burning tires.”
Subject to receiving regulatory approval, GCC proposes to use about 300,000 tires a year, replacing one-third of the plant’s coal consumption.
That would account for about 10 percent of the estimated 3 million tires discarded each year in Colorado.
Depending on market prices, tires for fuel can cost about 25 percent more per ton than coal, but the price difference is offset by rubber’s 30 percent higher energy content.
Supporters say that burning rubber in place of the more common coal in cement plants produces fewer emissions, slows the depletion of finite fossil fuels and reduces landfill clutter.
Opponents counter that burning rubber contributes to respiratory diseases, causes odors and emits more harmful dioxins and volatile organic compounds than coal or natural gas.
The polarized viewpoints can be partly explained by variations in the effectiveness of incineration and emissions-control systems, said Kirsten King, manager of the stationary sources program of the Colorado Department of Public Health and Environment.
The agency reviews companies’ combustion-system tests and monitors emissions. But violations can occur when equipment malfunctions.
If GCC were to burn tires, it would still use the plant’s existing “baghouse” emissions control system that filters out the majority of particulates, nitrogen oxides and sulfur oxides that are created from burning fossil fuels.
Unlike coal, burning tires produces no mercury and fewer heavy metals such as cadmium and chromium, King said. But she added that if rubber is not totally combusted, it can emit other potentially toxic organic compounds.
“The tricky thing about tire-derived fuel — any fuel — is that if you burn it completely, it’s a pretty clean process,” she said. “But the concerns are when you don’t have good, complete combustion.”
Steve Raabe: 303-954-1948 or sraabe@denverpost.com
