Waste Recycling System Could Supply 80 Percent of Nation's Energy

Integrated system also could generate high-end products for profit.

If all of the cattle, swine and poultry waste across the United States could be collected and converted to electricity, the resulting energy could produce 80 percent of the nation’s current electrical power needs, while also generating marketable high-end plants and extracts.

And the system works, at least on a smaller scale, according to research by a Texas Tech University civil engineering professor.

Clifford Fedler, also an associate dean at Texas Tech’s graduate school, says the country is largely ignoring an unlimited source of renewable energy – animal waste and other biomass – which is nothing more than any dry organic material – yard clippings, paper, residual material from cotton fields or other agricultural leftovers.

Fedler funded the research with a grant from the State Energy Conservation Office (SECO). He recently received a second grant from the organization to research an economic analysis of his biomass recycling system. Other departments across campus are assisting in the analysis; agricultural economics to assess marketing costs, and industrial engineering to assess the engineering economics of the system.

"The U.S. Department of Agriculture put out a report two years ago that says in the future, there will be 1.2 billion tons of biomass available for energy production," Fedler said. "What I have found is that if animal waste is recycled into biomass (dry material) rather than using fresh water sources, we have the potential to produce more than 4 billion tons annually, which is sufficient to produce nearly 80 percent of the nation’s current electrical energy usage."

In addition, the heat produced in the conversion process could be used in ancillary businesses such as greenhouse vegetable systems for year-round production, Fedler said.

Biomass energy has several advantages over wind and solar energy – mainly that it can be designed to be available 24/7, whereas wind and solar energy are site specific and rely heavily on climatic conditions and time availability.

By integrating various technologies together, such as water recycling with fish production, not only can additional biomass be generated, but negatively impacted water can be remediated, resulting in a cleaner environment. Additionally, integrated systems have the potential to produce valuable by-products that result in more economically viable systems, new jobs, and sustainable economic growth, particularly in rural communities.

Fedler’s integrated modular production system would operate slightly differently in different parts of the country, depending on the resources available at a given locale.

For example, in an arid or semi-arid region like West Texas, cattle waste from a feedlot could be fed directly into a gasification system for conversion to energy. The feedlot runoff water is treated in a pond, and then would flow to a series of smaller ponds where aquatic plants such as cattails and water hyacinth are produced. The plants are another form of biomass that also can be supplied to the gasifier, increasing the total energy output from the cattle feeding operation.

After this level of treatment, the water could produce a high-protein plant, such as duckweed, for use in the cattle feed. After the duckweed treatment, the water is of high enough quality that it can be used to water the cattle or to produce fish that can be sold in the aquarium market. If fish are grown in the system, the duckweed would be collected and used as the fish feed instead of adding it to the cattle feed. If the biofuel produced by the gasifier from the biomass is not used to produce electricity, it could be burned as an energy source for feed processing or separated to produce hydrogen gas and carbon fiber, a high-strength structural material.

In other areas of the country where confined animal feeding operations are prevalent, the modular system would require additional steps. As with the other example, the runoff water can be used to produce fish as another product to market for profit. The water from the fish production system could be used to produce other edible plants such as organic tomatoes or other organic food plants.

In either case, plants could be grown specifically for their profitable extracts to be used in nutritional supplements, with all of the by-products being consumed on-site. Many of the plant extracts are of much higher value than traditional plants, allowing this portion of the processing to provide additional income from the integrated recycling process.

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CONTACT: Clifford Fedler, professor, Department of Civil Engineering, Texas Tech University, (806) 742-2801 ext. 255, or clifford.fedler@ttu.edu.