Carbon footprint of sugar production in Mexico

Abstract

Global warming, caused mainly by increased worldwide emissions of greenhouse gases, is currently one of the greatest threats to the environment and human societies. Mexico has set an ambitious goal of reducing 30% of its greenhouse gases emissions by year 2020. The sugar agroindustry has been identified as one of the opportunities for mitigating emissions in this country. The aim of this work is to contribute towards identifying policy measures and practices for low-carbon sugar production by assessing the carbon footprint of sugar produced in four sugar mills in Mexico using a life cycle assessment method. System boundaries include agricultural practices, sugarcane harvesting, cane milling and sugar conversion. The results show that sugar production has carbon footprint values in the range of 0.45–0.63 kg CO2e/kg sugar. In these four cases, the agricultural stage contributes the majority of carbon emissions (59–74%). Most greenhouse gases emissions in the agricultural stage were from fertilizer production, nitrous oxide (N2O) emissions and biomass burning. The industrial stage contributed with 14–30% of total greenhouse gases emissions, mainly due to fossil fuel and bagasse use. The carbon footprint value is particularly sensitive to nitrogen fertilization, nitrous oxide emissions from the soil and sugarcane yields. Cogeneration in sugar mills could become an important way to reduce the carbon footprint of sugar and to produce electricity with low carbon emissions. We show the impact of different carbon footprint performance of sugar production process in Mexico. Data used on this manuscript came from real field measurements, and our results are accompanied by sensibility and uncertainty analyses. This is the first time that life cycle assessment has been used to estimate the carbon footprint of sugar production in Mexico including agricultural, industrial and transportation boundaries, to identify greenhouse gases mitigation opportunities. Studying techniques for improving sugar cane yield, making fertilizer use more efficient, minimizing cane burning and developing efficient cogeneration in sugar mills with bagasse as fuel is scientifically relevant. Applying concrete public policy measures to these areas of opportunity would allow production of low carbon sugar in Mexico. The results of this study may also be used as reference by other countries with similar sugar production conditions.