Assessment of CO2 emission rate from extended area sources with WindTrax model in a dairy cattle farm

A. Mattia, M. Merlini, F. Squillace, G. Rossi, L. Conti and V. Becciolini*

University of Florence, Department of Agriculture, Food, Environment and Forestry,
via San Bonaventura 13, IT 50145 Firenze, Italy
*Correspondence: valentina.becciolini@unifi.it

Abstract:

This paper aimed to evaluate the WindTrax model to quantify CO₂ (carbon dioxide) emissions in a commercial dairy cattle farm in Central Italy with a low-cost measurement system. A field trial of 20 minutes was conducted in February 2023, using two G-eko 2.0 MSPs (multi-sensor platforms), an anemometer, and a GNSS receiver, in unstable atmospheric conditions. Then, 5-minute averaged data were used as input in the WindTrax software for applying the backward Lagrangian Stochastic model. The model was used for calculating four mean CO₂ emission rates (0.20212 ± 0.04994 g m^-2 s^-1) with 50,000 particles and the horizontal dispersion of CO₂ concentrations around the sources using different numbers of particles (5,000, 10,000, 30,0000, and 50,000). Atmospheric dispersion maps, confidence interval concentration maps, and vertical profile plots were obtained by increasing the number of particles. The model shows better performances, in terms of confidence intervals, with a high number of particles with a stabilization of modeled median values between 30,000 and 50,000 particles. Horizontally, the lowest confidence intervals (near to zero) were obtained at 100–150 m from the sources along the wind direction, suggesting that the downwind sensor could be placed at a greater distance. Similarly, a better-defined vertical trend in modeled concentrations is observed as the number of particles increases. Wind gusts could have a great effect on emission rate calculation with limited sampling periods, as in this case, but simultaneously unstable atmospheric conditions affect the increased dispersion and dilution of CO₂.

Key words:

Analysis of environmental conditions in two different Compost Bedded Pack Barn systems for dairy cattle

R.R. Andrade¹, I.F.F. Tinôco², F.A. Damasceno³, D.A. Valente², C.E.A. Oliveira², V.C. Oliveira², G. Rossi⁴ and M. Barbari⁴

¹Federal University of Goiás, Department of Biosystems Engineering, College of Agronomy, BR74690-900, Goiânia, Brazil
²Federal University of Viçosa, Engineering Department, BR36570-000 Viçosa,
Minas Gerais, Brazil
³Federal University of Lavras, Engineering Department, BR37200-000 Lavras, Minas Gerais, Brazil
⁴University of Florence, Department of Agriculture, Food, Environment and Forestry, Via San Bonaventura 13, IT50145 Firenze, Italy
*Correspondence: matteo.barbari@unifi.it, rafaella.andrade@ufg.br

Abstract:

The objective of this study was to analyse and compare the thermal environment of dairy cattle facilities in an open compost bedded pack barn (CBP) with natural ventilation and closed CBP (without thermal insulation) and climate control system. The research was conducted in a property located in Zona da Mata, Minas Gerais, Brazil. During the summer and for different periods of the day, the following average environmental variables observed inside the facilities were measured: dry bulb temperature, relative humidity and Temperature and Humidity Index (THI). The results were submitted to an analysis of variance to determine the significance of the variables in the different treatments. It was found that the closed and climate control system CBP promoted greater control of the facility’s internal microclimate, registering smaller thermal amplitudes and a greater reduction in the animals’ exposure time to stressful thermal conditions, compared to the CBP with natural ventilation. However, during summer afternoons, comfort indices indicated moderate stress. It is concluded that the closed CBP, regarding the analysed variables, indicated potential use, provided that a careful study of the climate of the region is carried out before implementation, the factors related to the ambient conditioning and better insulation of the construction are adjusted. The climatic variables inside the open CBP indicated a high stress condition for the animals, suggesting the placement of positive pressure fans and sprinklers properly distributed in the feed alley, to guarantee benefits to the entire area of the animal housing.

Key words:

animal welfare, Housing systems, livestock farming, mechanical ventilation, thermal environment