Optimizing the water, carbon, and land‐use footprint of bioenergy production in Mexico ‐ Six case studies and the nationwide implications

Abstract

This study aims to answer the question if and how biofuels can be produced in Mexico without aggravating water scarcity, reducing greenhouse gas (GHG) emissions and avoiding indirect land-use changes. We analyzed environmental impacts of six potential maize-bioethanol production systems in Mexico on water resources, land use, and GHG emissions by using a life cycle assessment approach. Three irrigated high-input maize systems and three rain-fed low-yield systems were analyzed. Inventory data was acquired by soil sampling and interviews with farmers. For the water footprint, fi eld water balances were modeled using the Food and Agriculture Organization (FAO) AquaCrop Model. For the carbon footprint, the BioGrace tool was used. Based on the results of status-quo analysis, scenarios with improved agricultural management were defi ned to identify optimization potential. Additionally, the producible amount of biofuels was estimated on a national level. The analyses showed that improving management in rain-fed agriculture offers the best opportunities for biofuel production without compromising regional water availability and without unwanted indirect effects on food prices and GHG emissions. Around 3.4% of Mexican gas consumption could be produced from maize bioethanol in Mexico without the above mentioned unwanted effects. By optimizing green water use in rain-fed maize production, around 3 billion m 3 of non-productive soil evaporation would be put into productive use. This is around 10% of the total water extracted from aquifers in Mexico. From this we conclude that unproductive soil evaporation is an underestimated water resource which should be considered in water management.

Greenhouse gas emissions and mitigation potential of hybrid maize seed production in northwestern China

“…Electricity generated from coal-based sources makes irrigation a key source of GHG emissions from agriculture (Rothausen & Conway, 2011;Zou et al, 2015). When compared with rain-fed agriculture, a greater part of GHG emissions from irrigation-oriented production systems comes from the energy used for irrigation (Grassini & Cassman, 2012;Hennecke et al, 2016). Irrigation-related energy consumption accounted for 13.3% of the total GHG emissions in maize production systems on the Loess Plateau in China .…”

Design of biorefinery systems for conversion of corn stover into biofuels using a biorefinery engineering framework

“…Examples of reference equipment capital costs are shown in Tables S10 and S13 of the Supplementary Materials. Hennecke et al (2016) and allocated to straw using average ratio from data in Kim et al (2009).…”