The increasing population of urban areas is placing several environmental challenges on the management of cities. One of the most critical ones is solid waste generation. In 2012, each inhabitant of urban areas produced 1.2 kg of solid waste per day, an amount that is expected to increase 18% by the year 2025. As a result, land area available for landfill storage is becoming scarce. However, land availability is not the only problem related to waste disposal. Greenhouse gas (GHG) emissions play an important role in the environmental problems associated with waste management. Landfill storage of MSW contributes 20% to CH₄ emissions in the United States. These waste-derived environmental concerns are not exclusive of developed economies. Mexico, a newly industrialized country in Latin America, generated 41 million metric tons of MSW in 2011 from which only 10% was recycled. This issue, coupled with the increasing GHG emissions in the country, highlights the need of new waste disposal alternatives. One of the most interesting options is the use of MSW for the production of transportation fuels, by means of pyrolysis and catalytic upgrading to hydrocarbon fuels. This process is based on the thermal degradation at moderate temperatures under an oxygen-free atmosphere. Nevertheless, little information is available regarding the potential contribution of MSW-derived fuels to annual fuel consumption and its environmental impacts. Therefore, in the current study a resource assessment and cradle-to-grave carbon footprint analysis were carried out to evaluate the contribution to annual fuel consumption and climate change impact of MSW-derived fuels in Mexico.

Data from the Mexican Institute of Statistics and Geography and U.S. Energy Information Administration database were consulted for the resource assessment. The life cycle assessment methodology was applied to estimate the GHG emissions of two proposed pathways (“organics” and “polyolefines”), using a functional unit of one MJ of fuel produced. Both pathways comprised the stages of collection, separation, feedstock transportation, size reduction, fast pyrolysis, fuel distribution, and vehicle operation. Stages of hydroprocessing and avoided landfill emissions were considered only in the “organics” pathway. The emission factors for each stage were obtained from research papers and the Ecoinvent database available in the software SimaPro. The results showed that in Mexico 4.2 million metric tons of hydrocarbon fuels can be produced through MSW pyrolysis. This amount can contribute with 7.1% of the current national fossil fuel consumption. According to the carbon footprint analysis the proposed “organics” pathway produced savings of -9.5 g CO₂ eq. per MJ of fuels mainly due to avoided emissions from landfill disposal. The proposed “polyolefins” pathway generated 88.0 g CO₂ eq. per MJ which is a value 7.8% lower compared to emissions from fossil fuel production and use (95.5 g CO₂ eq. per MJ). Finally, these results were used to estimate a mixture that produces an advance biofuel (60% savings compared to the fossil fuel production). This mixture was comprised of 78.8% (wt) “organics” and 21.2% “polyolefins”. These findings point the waste-to fuel pathway as an interesting research area for the production of pyrolysis-derived fuels.