PUBBLICAZIONI
BIODIET: development and test of lignocellulosic bioderivates for diesel engines to reduce emissions in the urban environment
ISAF 2011 and 2nd lignocellulosic bioethanol conference-14 October 2011, VERONA
Abstract The BIODIET project, supported by the Italian Ministry for Environment, investigates the possibility of using lignocellulosic biomass derived liquids for addition or blending to fossil fuels. The target fuel is diesel oil, i.e. compression ignition engines, thus addressing a different goal than the usual gasoline chain, in which bioethanol is normally blended. The possibility to penetrate the diesel market will open new possibilities for the introduction of sugar-derived liquid biofuels. The project will explore the options offered from the “sugar” chain derived from lignocellulosic biomass fractionation through pretreatment and hydrolysis. Either the direct use of ethanol blended at small amount in diesel oil, or derivatives from the sugar (bio-hydrocarbons) and/or the ethanol (oxygenated additives as acetals, ethers, esters, etc) will be considered. Literature analysis as well as lab scale study will be carried out, to select the most interesting products and processes. The selected option will be considered for engine test in a small bench, where performances and emissions will be monitored. The sustainability of the entire chain will be examined, and a specific LCA conducted on the preferred solution, while results disseminated at the widest possible audience.
Keywords diesel oil . bioethanol . lignocellulosic biomass . sugars
2nd generation lignocellulosic bioethanol: is torrefaction a possible approach to biomass pretreatment?
Publisched online 15 February 2011
Abstract Biomass pretreatement is a key and energyconsuming step for lignocellulosic ethanol production; it is largely responsible for the energy efficiency and economic sustainability of the process. A new approach to biomass pretreatment for the lignocellulosic bioethanol chain could be mild torrefaction. Among other effects, biomass torrefaction improves the grindability of fibrous materials, thus reducing energy demand for grinding the feedstock before hydrolysis, and opens the biomass structure, making this more accessible to enzymes for hydrolysis. The aim of the preliminary experiments carried out was to achieve a first understanding of the possibility to combine torrefaction and hydrolysis for lignocellulosic bioethanol processes, and to evaluate it in terms of sugar and ethanol yields. In addition, the possibility of hydrolyzing the torrefied biomass has not yet been proven. Biomass from olive pruning has been torrefied at different conditions, namely 180–280°C for 60–120 min, grinded and then used as substrate in hydrolysis experiments. The bioconversion has been carried out at flask scale using a mixture of cellulosolytic, hemicellulosolitic, β-glucosidase enzymes, and a commercial strain of Saccharomyces cerevisiae. The experiments demonstrated that torrefied biomass can be enzymatically hydrolyzed and fermented into ethanol, with yields comparable with grinded untreated biomass and saving electrical energy. The comparison between the bioconversion yields achieved using only raw grinded biomass or torrefied and grinded biomass highlighted that: (1) mild torrefaction conditions limit sugar degradation to 5–10%; and (2) torrefied biomass does not lead to enzymatic and fermentation inhibition. Energy consumption for ethanol production has been preliminary estimated, and three different pretreatment steps, i.e., raw biomass grinding, biomass-torrefaction grinding, and steam explosion were compared. Based on preliminary results, steam explosion still has a significant advantage compared to the other two process chains.
Keywords Torrefaction . Lignocellulosic ethanol . Biomass pretreatment . Hydrolysis