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Title
Second-generation ethanol through alkaline fractionation of pine and aspen wood
Authors
Mikael Jansson Niklas Berglin and Leelo Olm
Received
November 19, 2009
Published
Volume 44 Issue 1-3 January-March
Keywords
bioethanol, alkaline pretreatment, converted pulp mill, pine, aspen, mass balance, energy balance,
Abstract
Pre-treatment studies on pine and aspen wood with alkaline fractionation were performed, the experimental results obtained being used as input for assessing the conversion of an existing pulp mill to ethanol and lignin production. By the LignoBoost process, the extracted lignin could be used in the lime kiln to replace fuel oil, while the lignin not needed in the lime kiln could be sold as a by-product. In addition to fuel applications, lignin could be used in a wide range of bio-based product applications, which would increase the value of the extracted lignin and increase the total revenues. A WinGEMS model was used to calculate mass and energy balances, and the results were used for an economic evaluation of the concept. The assessment indicated that the proposed alkaline concept would have reasonable production costs from both pine and aspen wood, comparable with the bioethanol produced from grain in Northern Europe today, i.e. about 0.45 €/L ethanol (~5 SEK/L). The production rate of a typical mill producing 1000 tonnes of pulp per day before conversion would be in the order of 140 000 m3 of ethanol per year, as depending on the raw wood material. The corresponding lignin production would range from 25 000 to 63 000 tonnes per year. The use of alkaline delignification to produce a substrate with low lignin content for the enzymatic hydrolysis builds entirely on known and well-proven technology, yet it needs to be further developed. The process chain from enzymatic hydrolysis to ethanol is very similar to that used today for grain ethanol. Altogether, the technical risk should therefore be low.
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