Company advocates for the use of biodiesel at power plants

January 10, 2012

BY Erin Voegele

Alabama-based Clean Energy Pathways Inc. is working to help coal-fired utilities meet state and federal compliance standards by helping to identify methods to increase efficiency and produce a portion of renewable energy. This includes the use of biodiesel to offset some of the fossil-based fuel that is fed to the boiler. According to Jon Chynoweth, Clean Energy Pathway’s director of marketing, his company recently established a memorandum of understanding (MOU) with the Mid-Atlantic Soybean Association to work together to promote the cogeneration of soy biodiesel in coal-fired power plants.

According to Clean Energy Pathways, substituting a portion of the coal that is used to fuel these plants with biodiesel, when coupled with infrared thermal monitoring, can optimize boiler efficiency while aiding compliance with renewable portfolio standards, the renewable fuels standard (RFS2), mercury and air toxics standards and the cross state air pollution rule (CSAPR). “We generate more than 50 percent of our electricity from coal in this nation,” said Chynoweth. Biodiesel can be implemented at these facilities in several ways, including as a liquid fuel for flame stabilization, as a start-up fuel or as a component to be co-fired with coal. Chynoweth and Clean Energy Pathways are focused on the latter of the three options.

Chynoweth said that his company has been involved in a trial that involved the use of biodiesel co-firing at a small coal-fired utility. A report compiled by that facility’s plant manager demonstrated that offsetting 10 percent of the plant’s coal fuel with biodiesel on a Btu basis resulted in significant reductions in many regulated emissions. While biodiesel is more expensive than coal on a Btu basis, Chynoweth noted that its use can result in significant cost benefits in maintenance.

The biggest maintenance issue at coal-fired power plants has to do with the boiler tubes, which are radiator-like pipes in the wall of the boiler. Water flows through those boiler tubes, where it is heated into steam that powers the plant’s generator, creating electricity. When power plants burn coal Chynoweth said a great deal of soot builds up on the boiler tubes. That soot acts as insulation, making the facility less efficient. Coal also produces an average of 160 pounds of fly ash from every ton of coal that it burns. According to Chynoweth, the fly ash adheres to the soot and can form slags and clinkers. Left unchecked, he said these deposits can grow to the size of small car, putting pressure on boiler tubes and causing them to separate from the boiler walls. There are also disposal issues related to fly ash, as it contains several toxic materials and must be landfilled.

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Chynoweth said replacing 10 percent of the coal entering a facility with biodiesel on a Btu equivalent basis results in a 10 percent reduction in soot and fly ash production. This can significantly reduce a facility’s maintenance costs.

Clean Energy Pathways offers customized workshops to companies where these benefits and additional efficiency measures are discussed in greater detail. According to the company, the workshops, led by Wayne Ruddock, a professional infrared thermographer and instructor with 30 years of experience, the workshops are aimed at plant management, fuel procurement, and environmental compliance and maintenance officers, particularly those in the 28 states affected by CSAPR. "One purpose of the workshop is to explain how compliance with RPS, RFS2, MATS and CSAPR can actually work to the utilities' advantage if liquid biofuels are substituted for coal," Ruddock said. "Tests have shown these fuels reduce SOx, CO2 and fly ash in proportion to the amount substituted for coal Btus. Liquid biofuels also reduce soot and slag buildup on boiler tubes, which improves heat transfer efficiency, maintenance and operating costs. We will also explain how thermal imaging is used to monitor boiler tubes for slag/soot buildup and temperature, enabling a plant to make appropriate adjustments to operate the boiler in its 'sweet spot' for highest efficiency."

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