CO2 as a tracer gas for determining the air exchange in a cow barn

Abstract

Milk and beef production goes along with the atmospheric emission of climatically active gases (CO2, CH4, N2O, NH3, H2S), which create a “greenhouse effect” and damage the environment. A lactating cow may release up to 7 kg of gases in CO2-equivalent per day. To control and reduce emissions of these gases, it is necessary to determine their mass. The direct measurements pose a certain problem under the natural ventilation system in the cow barns. The current solution is the indirect measurements making use of tracer gases. The research aimed to refine the methodology for calculating the air exchange rate using CO2 as a tracer gas in the cow barn environment. The research included the experimental study on the dairy cattle farms and calculation of air exchange in the cow barns. Our research confirmed that the air exchange, temperature and air velocity had a close interrelation. They affected the gas composition of the inside air in the cow barn. The determination coefficient of the regression equation R2 = 0.99 testified to the unconditional influence of air exchange intensity on CO2 concentration in the cow barn. In winter, the average CO2 concentration in the cow barn was 2.4 times higher than in summer. That was determined by the difference in the air exchange by 2.3 to 8 times. Variation coefficients characterizing the CO2 dispersion over the cow barn area were 16.1 % in winter and 17.9 % in summer, i.e. did not differ significantly. So, the method of calculating the air exchange with CO2 as a tracer gas can be used to determine the emissions of climatically active gases on cattle farms.