Assessing the environmental sustainability of ethanol from integrated biorefineries

This paper considers the life cycle environmental sustainability of ethanol produced in integrated biorefineries together with chemicals and energy. Four types of second-generation feedstocks are considered: wheat straw, forest residue, poplar, and miscanthus. Seven out of 11 environmental impacts from ethanol are negative, including greenhouse gas (GHG) emissions, when the system is credited for the co-products, indicating environmental savings. Ethanol from poplar is the best and straw the worst option for most impacts. Land use change from forest to miscanthus increases the GHG emissions several-fold. For poplar, the effect is opposite: converting grassland to forest reduces the emissions by three-fold. Compared to fossil and first-generation ethanol, ethanol from integrated biorefineries is more sustainable for most impacts, with the exception of wheat straw. Pure ethanol saves up to 87% of GHG emissions compared to petrol per MJ of fuel. However, for the current 5% ethanol–petrol blends, the savings are much smaller (<3%). Therefore, unless much higher blends become widespread, the contribution of ethanol from integrated biorefineries to the reduction of GHG emissions will be insignificant. Yet, higher ethanol blends would lead to an increase in some impacts, notably terrestrial and freshwater toxicity as well as eutrophication for some feedstocks

Life Cycle Assessments of Waste-Based Biorefineries\u2014A Critical Review

In recent years advanced biorefineries based on organic residues and waste have gained increased attention for their potential to obviate first-generation bio-refineries environmental burdens. During the conceptual design phase of an advanced biorefinery the role of Life Cycle Assessment (LCA) is crucial for providing information on its envi-ronmental performances, better solutions, preferable process setup, more suitable feedstock, trade-off, and so on. This review focuses on advanced biorefineries LCAs in order to accomplish a synthesis of the state-of-the-art from the methodological point of view. Some main methodological issues have been analyzed and discussed on twenty-four LCAs. Attention has been drawn to functional units, system boundaries, invento-ry data collection, allocation methods and multifunctionality management ap-proach. Results show different approaches and solutions to the analyzed aspects but some clear addresses can be pointed out. It has been observed that LCA of biore-fineries can be classified in three different types in base on focal aim, and then functional units are consequentially defined. A large variability has been ob-served regarding system boundaries even if \u201ccradle-to-gate\u201d appears the most common. Inventories are mainly based on secondary data due to the very innova-tive features of the analyzed technologies. No general consensus has been ob-served concerning allocation of environmental impact between co-products