It is well known that current US energy services are not sustainable. Endeavor for additional accessible and reliable energy supplies, especially the thrust for renewable energy production, is urgently needed to reduce the foreseeable US energy crisis. Among them, the large-scale biofuel production is considered as one of the most important alternative energy sources. However, massive production of biofuel may lead to deterioration of valuable ecological system services, which could be noticeable only after a long period of time. Such kinds of ecological services include purification of air and water, mitigation of droughts and floods, generation and renewal of soils, maintenance of biodiversity, protection from the solar UV rays, moderation of weather extremes, cycling and movement of nutrients, and etc. Since ecological services are essential to global sustainability, once they were identified irreversibly deteriorating, it would have resulted in profound global impacts or disasters.

Therefore, this paper will address the potential harmful ecological services impacts (HESI) due to large-scale production and usage of biofuels. To study this complex and challenging issue, this paper, taking the corn-ethanol production as an example, first conducted the life-cycle HESI analysis for biofuel production, which covers every stage of biofuel material flow chain. Then, emergy-based input-output analysis (IOA) method is employed to identify the proposed HESI index, such that negative ecological services impacts could be clearly quantified. It demonstrates that current biofuel thrusts for renewable energy are most likely shortsighted behaviors that may not be viable in long-term sustainability. Finally, based on the developed methodology, several suggestions for avoiding HESI from biofuel productions are discussed.