Burning waste paper pellets

An alternative, environmentally safe fuel source — pelletized waste paper — proved cost-effective in a three-phase test burn. Two Department of Energy laboratories teamed up with private industry to burn paper pellets and coal to create steam at the Idaho Chemical Processing Plant's Coal Fired Steam Generation Facility. The $125,000 cooperative research and development agreement involved the Idaho National Engineering Laboratory conducting the test burn, the National Renewable Energy Laboratory providing a technical expert in paper combustion, the R. W. Beck Company analyzing the test burn results, and Solid Waste Integrated Systems analyzing pellet composition and providing 50 tons of pelletized paper.

The Laboratory is a DOE reservation with numerous facilities scattered over 800 square miles of the Idaho desert. The logistics of serving the entire site, therefore, are complicated. However, the pelletization test burn proved so successful that the Idaho Chemical Processing Plant is planning to install a pellet-making machine to serve the balance of the facilities at the Idaho National Engineering Laboratory.

Three objectives of the tests

• The first objective was to determine whether the existing coal crusher, bucket lifts, and screw auger were able to process paper pellets. Another element of this objective was to monitor the boiler efficiency and combustion process closely to determine if using this new fuel mixture was energy efficient.
• The second objective was to evaluate whether the Facility would operate within normal process limits while burning paper pellets. The third objective was to monitor atmospheric emissions to maintain standard compliance levels.

Research shows that waste paper burns cleaner than coal. It produces less nitrous oxides and sulfur dioxide that cause acid rain. The tests demonstrated that burning a ratio of 25 weight percent waste paper mixed with 75% coal meets the three objectives.

Problem statement

• The Chemical Processing Plant disposes of over a ton of waste paper and corrugated cardboard material daily. The entire laboratory generates an estimated four to six tons of wastepaper daily. In addition, site operations management wanted to reduce by half the amount of waste paper sent to landfills. This technology saves $500 a day in landfill disposal costs and $6,000 a day in handling, tracking, permitting, and disposal costs.
• The consequences of ignoring this problem include the loss of $1 million potential savings annually for the Chemical Processing Plant and an estimated loss of $5 million a year in fuel and landfill savings for Laboratory. Further negative consequences include the rapid filling of available landfill, increased potential for landfill fires, and greater release of methane gas into the atmosphere.

Project scope

• The existing paper pelletization equipment shreds waste paper and other combustibles, softens them with steam, then compresses and extrudes them into pellets. When burned, the pellets, mixed with coal and other fuels, produce process heat, steam, and in some cases, both process steam and electricity.
• The Chemical Processing Plant has two fluidized beds that use pressurized air to keep fine limestone particles in motion. When fuel is injected into these beds and ignited, the constantly moving limestone particles wear away the exposed surface of the fuel. This results in complete and efficient combustion. The limestone neutralizes the sulfur dioxide formed during the combustion and reduces the amount of nitrous oxide and other pollutants normally emitted.

Full implemention of this project requires installing a pellet-making machine as well as a shredder that is more suited to the paper pelletization process. Since the project provides wastepaper reduction for the Laboratory, it requires constructing more storage bins for pellets.

Cost analysis of the solution

• Converting waste paper to fuel pellets saves $500 per day in landfill disposal costs and more than $6,000 daily in ash handling and other variable costs. Also, there will be savings in future coal purchases. Each 1.5 tons of pelletized paper has the energy equivalent of one ton of coal. This provides a savings of $45 per ton in fuel costs.

Corporate strategy

• The Lockheed Idaho Technologies Company is using this pelletization technology to turn the waste paper stream into fuel at the Laboratory. Since this is the only fluidized bed coal combustion facility at any of the Department of Energy's laboratories nationwide, it serves as a test bed for continuing research and commercialization of alternate fuels. This project also supports Lockheed Idaho's goal of pursuing research in alternative fuels.

Regional and national applications

• We hope these tests will interest others and lead them to separate combustible waste from municipal waste streams. Some 65% of municipal waste can be recovered and burned as fuel. Another 25% can be recycled, leaving only 10% to dispose of in landfills. This reduction in solid waste diminishes the demand for landfill space resulting in a positive environmental impact nationwide. Another benefit of producing energy by waste combustion using solid waste pellets in fluidized beds is that it generates the least amount of ground and water contamination from pollutant emissions. If done on a large scale, major cities could eliminate enormous amounts of solid waste while selling the resultant energy produced to local industries.