May 2008

Utility turns paint waste into energy
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What was once seen as waste at an automobile manufacturing facility is being used to generate enough electricity for 70 homes, replacing 570 tons of coal a year.

Two assembly plants operated by Chrysler LLC near St. Louis, in Fenton, Missouri, are sending paint waste to a nearby electric utility instead of a landfill.

The 855 megawatt Meramec Plant, run by St. Louis-based Ameren Corp., blends the paint waste with coal and burns it in the plant’s boilers to generate electricity.

The idea to turn paint waste into energy originated when an Ameren account executive was talking with a Chrysler executive. The executive mentioned that the automobile manufacturer had paint overspray it was paying to dump in a landfill.

That discussion led to Ameren testing the process in a pilot program that turned approximately 650 tons of paint into energy from September 2006 to September 2007.

“Chrysler avoids dumping this material in a landfill. Ameren converts paint to power,” said Tim Fox, a supervisor in the communications department at Ameren, which serves 2.4 million electric customers and nearly one million natural gas customers.

The paint waste-to-energy process is out of the pilot stage and Chrysler sends its paint waste to Ameren on a regular basis. The paint waste has to have a certain heat content to be blended with coal and burned at the plant. The paint waste is first dried on the Chrysler property. Once it reaches the proper specifications it is hauled to the utility.

“For this project, we developed a more efficient process for preparing the paint solids – with some modest cost savings – and we no longer have to pay to send the material to landfill,” said David Lyons, in charge of energy planning at Chrysler.

The Fenton assembly plants manufacture the Dodge Ram light and heavy-duty pickup trucks and the Chrysler Town & Country and Dodge Grand Caravan minivans.

The Auburn Hills, Michigan-based Chrysler is now working to expand the program.

“We are currently investigating the possibility of extending this process to partnership with other electric utilities near our other plants,” Lyons said.

Researchers at Washington University in St. Louis did the initial research and development work to study the feasibility of turning the paint waste into energy. The researchers wanted to determine not only the feasibility of recycling the energy content, but also the impact on combustion characteristics to avoid any adverse emissions.

While the Fenton plant does not generate that much paint waste itself, a lot of manufacturers across the country send this type of waste to landfills, said Pratim Biswas, chair of the Department of Energy, Environmental and Chemical Engineering.

For every car that is painted about 2 ½ kilograms of paint solvent is recovered, Biswas said. “Now you can take it [paint] and mix it with coal and extract the energy content.”

There are 22 million vehicles manufactured each year in North America, which would mean 35,000 tons of recovered paint that is going to landfills, he estimated.

“It is a very small amount, but extremely valuable in terms of not disposing of waste and keeping it as something valuable,” Biswas said. “We hope it catches on.”

Biswas noted that since St. Louis is not at the center of auto manufacturing it is important for the Detroit automakers to expand the paint waste-to-energy process to other plants throughout North America. He said that there are also numerous other kinds of paint operations and other manufacturers that could benefit from the process.

Researchers also wanted to determine if the process of turning paint waste into energy could be used to reduce other emissions from coal combustion. The researchers tested the use of titanium dioxide to cut mercury emission from coal-fired electric generating plants. Mercury is released in trace quantities when coal is burned.

The paint solid residues contain titanium dioxide, which has the potential to remove mercury from coal power plant emissions without impacting other processes in the plant. Mercury is chemically bonded with titanium oxide in a process known as chemisorption and is potentially easier to trap in the plant’s emissions scrubber systems.

Biswas said the process to use titanium dioxide to cut mercury emissions from coal-fired electric generation plants worked on a laboratory scale. But he said that before the process is used on a larger scale, more research and development needs to be done.

“We still have to go back and reengineer the paint. Now you’ve got to go back to the paint manufacturer if you really want to take this to the next level,” he said.

Much of the electric power industry is studying the use of various chemicals to remove mercury from power plant emissions after government regulators implemented requirements to cut mercury emissions from coal-fired electric power plants.

Ameren supplied Washington University researchers with some equipment to test the mercury removal capabilities of carbon-based substances as part of the pilot program.

“As a utility that gets 86 percent of its generation from burning coal, we are very interested in their results. Ameren has been a leader in improving the environmental impact of our power plants and this is just an extension of those efforts,” Fox said.

“For example, for years we have burned used tires at our other plants, and we have decreased air emissions of compounds like sulfur dioxide and nitrogen oxide. The paint project takes those efforts a step further by helping another industry, and an important Ameren customer, improve its own environmental performance.”