Biofuel from oil-rich tree seeds: Net energy ratio, emissions saving and other environmental impacts associated with agroforestry practices in Hassan district of Karnataka, India

• Published in: Journal of cleaner production 2017-10, Vol.164, p.905-917
• Main Authors: Pragya, Namita, Sharma, Navin, Gowda, Balakrishna
• Format: Article
• Language: English
• Subjects: Agroforestry; Greenhouse gas; Net energy balance; Net energy ratio; Trees bearing oilseeds
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2017.07.005

The agroforestry system that integrate non-food, perennial trees bearing oilseeds (TBO) with agricultural crops on low quality land, has potential to sustainably produce biofuels with considerable GHG savings and has livelihood benefits for the farmers. We evaluated many TBOs with a life cycle assessment methodology. We quantified Net Energy Balance (NEB), Net Energy Ratio (NER) and greenhouse gas (GHG) emissions saving potential in comparison to fossil fuels. The study focused on agroforestry-based biofuel production from seven tree species i.e. Pongamia pinnata, Madhuca indica, Azadirachta indica, Simarouba glauca, Amoora rohituka, Calophyllum inophyllum and Jatropha curcas. In a comparative assessment with first generation biofuels from corn and soybean, agroforestry based biofuels had NER values from 1.42 to 2.03 while soybean and corn had NER values of 0.43 and 0.54, respectively, when only biofuel energy was considered. When co-products energy was also considered, the NER values of agroforestry based biofuels increased manifold and ranged between 4.2 and 6.44, while for soybean and corn it was 1.35 and 0.88 respectively. The GHG emissions saving of agroforestry based biofuels ranged from 24.3 CO2-Eq/MJ to 41.7 CO2-Eq/MJ, while soybean and corn had negative GHG emissions saving of −137 CO2-Eq/MJ and −99 CO2-Eq/MJ respectively. •When only biofuel energy was considered, agroforestry based biofuels had NER values from 1.42 to 2.03 while soybean and corn had NER of 0.43 and 0.54, respectively.•On adding energy from co-products, the NER of agroforestry based biofuels increased manifold and ranged between 4.2 and 6.44, while for soybean and corn it was 1.35 and 0.88, respectively.•The GHG emissions saving of agroforestry based biofuels ranged from 24.3 CO2-Eq/MJ to 41.7 CO2-Eq/MJ, while soybean and corn had negative GHG emissions saving.