1. Introduction
Energy supply not only affects nation’s energy security, but also affects sustainable development. The global rise
in energy demand and concern about increased greenhouse gas emissions make lignocellulosic biomass increasingly
to be recognized as having great potential for biofuel and biomaterial production based on the biorefinery concept
[1]. The advantages of lignocellulosic biomass as potential energy sources are their neutral carbon balance,
renewable character, large availability, independence of geographic location and improvement of local economy
derived from cultivation [2]. The chemical components of lignocellulosic biomass are cellulose, hemicellulose, and
lignin. Cellulose and hemicellulose can be converted to sugars (C-6 and C-5) through biological or chemical
conversion, and these sugars can be fermented to ethanol or other valuable chemicals [3]. However, lignin is a
polymer of phenolic nature became an inhibitor of enzymatic reactions. Lignin not only prevents cellulase from
forming cellulose but also adsorbs the enzyme, thereby inactivating it for cellulose hydrolysis [4]. One of the largest
lignocellulosic sources in Indonesia is wastes from oil palm industry, such as oil palm empty fruit bunches (EFBs)
or frond. Oil palm production in Indonesia increased from 17.54 million tons in 2008 to 23.52 million tons in 2012
[5]. The dry weight of EFBs is about 8% of the dry weight of FFB (Fresh Fruit Bunches) [6], or 39% of the weight
of CPO produced [7]. The chemical component of EFBs is 44.21% cellulose, 16.68% hemicelluloses and 35.51%
lignin [8]. Cellulose is the highest component of EFBs that can be converted to ethanol.