Research project aimed at helping to reduce energy costs
PRINCESS ANNE, Md. — A trio of integrated research projects at the University of Maryland Eastern Shore are focused on helping poultry farmers reduce energy costs.
Felix Buabeng, a graduate research assistant in the university’s Food Science and Technology program, and advisors are testing the viability of using an acid solution to reduce ammonia in poultry houses; in-vessel composting of poultry litter to capture heat and painting the house roof to trap heat inside and using a “solar curtain” along the side of the poultry house to bring in more heat.
“At the end of it we will try to bring all these together and evaluate the heat recovery potential,” Buabeng said.
The ammonia absorption portion of the research consists of testing two systems; one with the acid solution running through a coil of the gas-permeable membrane in a tube and another with a sheet of the same membrane covering the solution in a gutter.
Buabeng said the recommended level of ammonia in poultry houses is 25 parts per million for bird and grower health but during certain times of the year that’s difficult to reach and levels of 50 to 100 ppm are more common.
The acid solution essentially binds ammonia to it as it passes through the membrane.
Once ammonia gas passed through the membrane and was in contact with the acidic solution ammonium salt was formed, which was retained and concentrated in the acidic solution. The more ammonia that’s absorbed the less a grower may have to ventilate the poultry house, saving energy.
“We developed the system to reduce the ammonia level, if not to 25 ppm, at least to a level that’s more comfortable,” he said.
The experiment consisted of three treatments; 1) Control with no birds and membrane systems, 2) birds alone, and 3) birds with both membrane systems, with separate rooms per treatments.
Each room contained 400 birds with old litter on the floor.
After some initial adjustments to the systems, Buabeng said the results of the first trial showed a 97 percent recovery rate of ammonia in the room with both systems installed when compared to the room without the system.
Bird mortality rate was higher in the room without the systems — 6.5 percent — as compared to the room with the installed system — 2.5 percent.
“We saw almost about 50 percent reduction in (mortality in) the treatment room,” he said.
But the more costly and more maintenance-heavy system using the tubular membrane was responsible for nearly all the reduction, he said.
Buabeng said he suspects air space between the membrane and the solution in the gutter system made it less effective so the next step is to conduct another trial separating the two systems and keep the membrane in constant contact with the solution, similar to the tubular system.
In the first trial, the gutter system relied on gravity to keep the solution moving as a way to keep costs down but the next trials will use a pump to ensure a more consistent flow.
“At the end of it we want to recommend the flat membrane to the farmer because it is less expensive and easier to maintain and that is what farmers want,” Buabeng said, as long as it is an effective system.
He said the acid solution used to absorb ammonia is getting a look as a fertilizer source for land application after it’s used in the poultry house trials.
The in-vessel composting component using wood chips and poultry litter generates heat and reduces pathogens in the litter and enhances its nutrient availability through stabilization.
“The focus was for the heat but another benefit was the nutrient stabilization,” Buabeng said.
In-vessel composting was more than adequate to reduce pathogens, stabilize nutrients, and eliminate noxious volatile emissions from the treated litter, he added.
In subsequent trials with the composting component, Buabeng said data will be gathered on how much generated heat is reused in heating the poultry house.
Buabeng also collected data on the heat radiated from different colors on the roof. Researchers painted half of the roof red and left half untreated.
The two halves were again divided in half with a radiant barrier installed to trap heat in one section each.
In the solar curtain system, plastic sheeting covering a potion of the sidewall radiates heat from the sun, heating air that is circulated through the poultry house.
With data from its initial trial, Buabeng said the system could save a grower about 20 to 30 percent on energy costs if the system were expanded to the length of the house.
The next step in the research is to expand the curtain and determine how to best combine it with the heat generated from the roof.
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