Researchers Find Ways To Turn Manure Into Power

Texas Senate Bill20, signed this week by Gov. Rick Perry, compliments research under wayto determine how and where biomass can be used. The new law requiresmore renewable energy to be developed and used in the next 10 years.

Combiningconsumer energy needs and agriculture industry trends with thelegislation will push the research to become reality, said Dr. JohnSweeten, resident director of the Texas Agricultural Experiment Stationat the Texas A&M University System Agriculture Research andExtension Center here.

Researchers have long worked with manureas a fertilizer and have studied ways to convert it into energy, butthis latest push of legislation and research should result in moreenergy projects becoming a reality, Sweeten said.

Research isconcentrating on finding alternative uses for the growing supplies ofmanure, Sweeten said. Irrigated cropland use of manure as a fertilizeris dwindling, but the livestock industry is growing.

Other trendscontributing to a potential excess are increasing imports ofgrain-based nutrients to feed the cattle; less irrigation water; andthe switch to crops which use less water and require fewer nutrients.

"Thingsare in reasonable shape now, but in 10, 20 or 30 years from now, weneed to have alternate uses that are not based exclusively on landapplication," he said.

Energy production has been researched formore than 20 years, but "$60 a barrel oil recruits a lot of interest inbiomass," Sweeten said.

"The question becomes, how do you convert biomass into energy?" he said.

Thesolid feedlot waste presents a different challenge than the liquidwaste from hog or dairy operations, Sweeten said. Researchers aretrying to determine what process and what mix of the product willcreate the most useable heat and, as a result, energy.

For thisstudy, composite samples of raw/mixed/uncomposted manure from theExperiment Station feedlot at Bushland have been sent for testing atseveral labs. The manure samples were harvested May 17-June 2 from twotypes of pens.

One set of pens were paved with fly-ash, abyproduct of the coal-fired power generating industry, and the othermanure was from unpaved pens. The manure was composted and test resultsfrom the two showed a large difference for several constituentsmeasured, especially ash content, Sweeten said.

Ash, an unusablematerial as far as energy is concerned, was lower in the compostedmanure samples from the paved pens than the dirt pens -- 20.2 percentcompared to 58.7 percent. As a result, the low-ash manure had abouttwice the organic matter and heating value, he said.

"The low-ashfeedlot biomass would be much better fuel than high-ash feedlotbiomass," Sweeten said. "The problem is, there is not that much of itin the commercial feedlots."

Large bulk samples from the compostpile that came from the paved pens will be tested further in asmall-scale combustion testing project in College Station.

Thesetest results will focus on using pulverized manure samples as reburnfuel in a secondary combustion chamber to lower the nitrogen oxides andspecific metal emissions from coal-firing in the primary combustionchamber, Sweeten said.

Re-sampling will begin next week uponcompletion of 50 days of composting of the two windrows. The analysiswill be repeated on the partially-composted manure to determine changesin fuel quality produced by more than six weeks of composting, he said.

Another research project involves using the byproduct combustion ash as a fertilizer or construction material, Sweeten said.

"Byassuring year-round uses of manure, the cattle feed yards in this areacould not only stay current on manure harvesting, but the fuel qualityof manure improves with more frequent harvest," Sweeten said. "An evengreater benefit is that frequent surface manure harvesting by scrapingis an accepted method of dust control."