Poultry litter recycled to create fertilizers and renewable energy Click to Enlarge - The Fibrominn plant in Benson, Minnesota generates electricity by combusting turkey litter and biomass and provides an outlet for growers to dispose of excess litter and earn income.
E-mail the author

The United States poultry industry is being assaulted on many fronts; by more stringent government regulations, by environmental and animal rights groups, and by escalating feed and electricity costs, just to mention a few. Manure management has become a prime concern for growers, a hot issue for communities, an annoyance for anyone living downwind from a poultry farm and everyone interested in minimizing nutrient run off that damages water quality and marine life. But it looks as though there is recycling relief in sight for handling the manure problem.

Called poultry litter in commodity form, it is a combination of manure and bedding materials such as wood shavings, sawdust, peanut hulls, shredded sugar cane, straw, or other dry, absorbent, low-cost organic materials. Of course, the commodity price fluctuates with the quality of the litter, seasonality, and is affected by the price of natural gas and oil used to make competitive chemical fertilizers. In Arkansas, poultry litter recently sold between $6 and $10 per ton – down from $15 a year ago. Long recognized as a good organic fertilizer that contains nitrogen, phosphorus and potassium, it has drawbacks. In raw form it can be applied only before a crop is planted, cannot be applied during the growing season and is not ideally chemically balanced to suit many plant nutrient requirements. For these reasons, growers face the challenge of managing excess supply.

Meanwhile, poultry litter is constantly produced in huge quantities because the United States is the world’s largest poultry producer and the world’s second-largest egg producer and exporter of poultry meat. Annual United States meat production totals over 43 billion pounds. Over four-fifths is broiler meat, most of the remainder is turkey meat, and a small fraction other poultry meat. Total farm value of United States poultry production exceeds $20 billion dollars with broiler production accounting for most of the value, followed by eggs, turkey, and other poultry.

As litter is produced, it is periodically removed from poultry houses and accumulates in large, outdoor stockpiles – often standing for months which presents odor, runoff, and potential pathogen problems.

To deal with excessive litter and more efficiently recycle the commodity, two new methods have been developed over the past several years – first, processing the litter into slow-release fertilizer pellets that can be applied anytime during the crop cycle and secondly, combusting the carbon content in the litter along with other biomass to generate electricity as well as recover approximately one-eighth of the raw feedstock as ash that is sold as a P & K (phosphorous and potassium) fertilizer with useful levels of micronutrients.

In 2001, Perdue AgriRecycle became the first United States company to introduce an environmentally sound alternative use for chicken litter. Perdue, one of the country’s largest poultry producers, joined forces with AgriRecycle, a company that helped develop litter pelletizing technology and built a large-scale plant in Sussex County, Delaware. Located in one of the country’s most concentrated areas of chicken production, it processes the equivalent of 400 poultry houses worth of litter each year. The process dries and pasteurizes the litter to make pellet and granular organic fertilizers that are sold in bulk for commercial applications or added to other products.

“As far as we know there is no other commercially sized plant of this type that takes chicken litter and converts it into organic fertilizer,” said Luis Luna, Perdue’s vice president of corporate communications. Luna reported that the demand for their organic fertilizer is very high because it is certified for organic production. Farmers, nurseries and landscapers find it very desirable because there are no chemicals, does not burn crops and contains 60 percent organic matter.

Power from poultry litter is now a reality.

Perdue does not pay for chicken litter, but carts away excess that saves the grower the cost of trucking. “Since we started, it has not been a profitable business, but this year we are starting to make some profit. In our years of operation, we have removed 40 million pounds of nitrogen, 20 million pounds of phosphorous and 30 million pounds of potassium that otherwise would have been applied to the land or used in some other way that could have runoff into the Chesapeake Bay. We knew this was the right thing to do environmentally, not because it was going to be a big money-maker. We have figured out how to do it profitably and we hope to do it on a continuing basis,” Luna added.

Power from poultry litter is the other option being closely watched by a number of poultry producing states.

Robin Morgan, Dean of the University of Delaware and Professor of Animal and Food Sciences said, “The State of Delaware has not allowed incineration of poultry litter due to regulations by the Delaware Department of Natural Resources and Environmental Control, so we really don’t have first-hand experience with this. Nevertheless, we are watching with interest because incineration of poultry litter is allowed in Maryland. My view is that if the incineration process is clean this could very well be another alternative for value added to poultry operations. The cost of energy is probably the largest uncertainty that poultry growers face, and indeed, energy is a huge issue for agriculture.”

Other than Delaware, there are no states that directly restrict the use of poultry litter as a fuel for resource recovery.

Minnesota became the first state where poultry litter was used to generate electricity when Fibrominn, a subsidiary of Fibrowatt LLC fired up a $140 million dollar plant in Benson in 2007. The Benson 55 megawatt power plant also became the largest biomass power plant in the country. Yearly it burns 500,000 tons of turkey litter and 100,000 to 200,000 tons of agricultural wastes. “The acceptance of our service in Minnesota has been very high. They recognize that in this day and age agricultural markets are getting more and more onerous from a regulatory perspective. Having an option like this relieves a lot of these pressures and growers recognize the value of having our alternative available,” said Terry Walmsley, vice president of environmental and public affairs for Fibrominn.

Fibrowatt first introduced poultry litter to generate electricity to the United Kingdom in the 1990s and built three plants there. Today, delegations from other United States poultry producing states are visiting and evaluating the Benson plant. Fibrowatt has already selected sites in North Carolina for three plants and is in the process of finalizing power purchase agreements (PPAs) with electric utilities.

Fibrowatt gathers feedstock from growers, primarily within a 50 mile radius of its plant, but will travel further depending on the volume and composition of the litter. Nutrient composition of manure varies with the type of bird, feed ration, proportion of litter to droppings and other factors. Consequently, Fibrowatt samples and analyzes litter for fuel value and nutrient content before entering into contracts with growers. Contracts are flexible to the needs of growers. In some instances Fibrowatt will actually clean out the poultry house, in others cases the grower does. A nominal price is paid for the litter so it is actually more of a service to help the grower dispose of and manage the manure.

Litter is transported in tightly covered trucks that travel on pre-arranged routes to minimize truck traffic in local communities. It is unloaded into a fuel storage building that is kept at negative pressure to prevent odor escape. Litter travels via a conveyor system to the boiler where it is combusted at over 1,500 degrees to destroy pathogens. The boiler produces high pressure steam that drives a turbine to make electricity that is sold to the utility under a PPA.

Unlike fossil fuels, when poultry litter and other biomasses are combusted no new carbon dioxide is released. Because of the clean-burning fuel and advanced pollution control equipment, the plant meets strict air emission limits for each of the major gases. Emissions are regulated and monitored by a continuous emissions monitoring system that logs and reports on emission performance. “We are regulated by federal and state environment regulations and pass all requirements. We use best available technology,” said Walmsley.

A byproduct of combustion is ash which is recovered and processed as a fertilizer. The ash consists of primarily high potassium and phosphorous. When looking the phosphorus and potassium content in the ash, it is comparable to a 0-17-13 fertilizer. This ash also contains secondary nutrients like sulfur as well as micronutrients like zinc.

Fibrominn reported that one of the benefits of its plant is the improvement in quality of life for neighbors of poultry farms. Poultry operations were often located in rural areas on land that was not particularly good for raising crops. As residential development encroached, poultry odor became an increasing problem. By handling the litter promptly or by avoiding long term stockpiling odor and runoff is reduced.

“What the industry finds important is that this is a sustainable solution. It saves the grower labor, cleanout, transportation and management time. When growers have an excess of manure that they can’t put on the land because they are regulated as to how much and when they can spread, our service allows growers to use the litter in appropriate concentrations and provides an alternative to monetize excess litter that could exceed crop nutrient requirements,” Walmsley summarized.