Reduction of atmospheric emissions due to switching from fuel oil to natural gas at a power plant in a critical area in Central Mexico

ABSTRACT

A case study was conducted to evaluate the SO₂ emission reduction in a power plant in Central Mexico, as a result of the shifting of fuel oil to natural gas. Emissions of criteria pollutants, greenhouse gases, organic and inorganic toxics were estimated based on a 2010 report of hourly fuel oil consumption at the “Francisco Pérez Ríos” power plant in Tula, Mexico. For SO₂, the dispersion of these emissions was assessed with the CALPUFF dispersion model. Emissions reductions of > 99% for SO₂, PM and Pb, as well as reductions >50% for organic and inorganic toxics were observed when simulating the use of natural gas. Maximum annual (993 µg/m³) and monthly average SO₂ concentrations were simulated during the cold-dry period (152–1063 µg/m³), and warm-dry period (239–432 µg/m³). Dispersion model results and those from Mexico City’s air quality forecasting system showed that SO₂ emissions from the power plant affect the north of Mexico City in the cold-dry period. The evaluation of model estimates with 24 hr SO₂ measured concentrations at Tepeji del Rio suggests that the combination of observations and dispersion models are useful in assessing the reduction of SO₂ emissions due to shifting in fuels. Being SO₂ a major precursor of acid rain, high transported sulfate concentrations are of concern and low pH values have been reported in the south of Mexico City, indicating that secondary SO₂ products emitted in the power plant can be transported to Mexico City under specific atmospheric conditions.

Implications: Although the surroundings of a power plant located north of Mexico City receives most of the direct SO₂ impact from fuel oil emissions, the plume is dispersed and advected to the Mexico City metropolitan area, where its secondary products may cause acid rain. The use of cleaner fuels may assure significant SO₂ reductions in the plant emissions and consequent acid rain presence in nearby populated cities and should be compulsory in critical areas to comply with annual emission limits and health standards.

Acknowledgment

This study was supported by UNAM under the program PAPIIT IN116215. The authors are grateful to Edgardo Moreno T. and Iris Violeta Cureño G. for the support provided during the development of this study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by DGAPA-UNAM through the projects PAPIIT IA100819 and IN112318.

Notes on contributors

Rodolfo Sosa E.

Rodolfo Sosa E., Elizabeth Vega are research professors at the Environmental Pollution Section, Centro de Ciencias de la Atmósfera, Universidad Nacional Autonoma de Mexico, in Mexico City, Mexico.

Ann Wellens

Mónica Jaimes is the sub-director of the Analysis and Modeling of the Secretaria del Medio Ambiente in Mexico City, Mexico.

Mónica Jaimes

Ann Wellens is a professor at the Engineering Faculty, Universidad Nacional Autonoma de Mexico, in Mexico City, Mexico

Gilberto Fuentes G

Gilberto Fuentes G., Elías Granados H., Ana Luisa Alarcón J., María del Carmen Torres B., Pablo Sánchez A. and Evelin Mateos D. are technical staff at the Environmental Pollution Section, Centro de Ciencias de la Atmósfera, Universidad Nacional Autonoma de Mexico, in Mexico City, Mexico

Sergio Rosas A.

Sergio Rosas A. is a consultant of the Environmental Department at the Comision Federal de Electricidad, in Mexico City, Mexico.