Life cycle water footprint analysis for second-generation biobutanol

Area of Science:

• Agricultural Science
• Environmental Science
• Energy Science

Background:

• Water is crucial for converting crops into bioenergy.
• Evaluating the impact of bioenergy technologies on water resources is essential.
• Biobutanol production from various biomass sources has different water implications.

Purpose of the Study:

• To analyze the life cycle water footprints of biobutanol derived from wheat straw, corn grain, and corn stover.
• To assess the influence of crop growing characteristics and climate conditions on water footprints.
• To identify the primary contributors to the water footprint in biobutanol production.

Main Methods:

• Life cycle assessment (LCA) methodology was employed.
• Water footprints were calculated for biobutanol production from three distinct biomass sources.
• Analysis considered crop growing conditions and local climate data.

Main Results:

• Life cycle water footprints for biobutanol were determined as 271 L H2O/MJ (wheat straw), 108 L H2O/MJ (corn grain), and 240 L H2O/MJ (corn stover).
• The crop production stage dominated the water footprint, with values of 269.89, 107.84, and 238.95 L H2O/MJ for wheat straw, corn grain, and corn stover, respectively.
• Gray water footprint, largely due to fertilizer use, constituted a significant portion (86-91%) of the total life cycle water footprint for all feedstocks.

Conclusions:

• Biobutanol production from corn grain exhibits the lowest life cycle water footprint among the studied feedstocks.
• Fertilizer application in crop production is the most substantial factor contributing to the gray water footprint and overall water consumption.
• Sustainable agricultural practices and optimized fertilizer management are critical for reducing the environmental impact of bioenergy production.