Suzana Yusup, Murni Melati Ahmad, Yoshimitsu Uemura,

Razol Mahari Ali, Azlin Suhaida Azmi, Mas Fatiha Mohamad and Sean Lim Lay

Abstract Various renewable energy technologies are under considerable interest due to the projected depletion of our primary sources of energy and global warming associated with their utilizations. One of the alternatives under focus is renewable fuels produced from agricultural wastes. Malaysia, being one of the largest producers of palm oil, generates abundant agricultural wastes such as fibers, shells, fronds, and trunks with the potential to be converted to biofuels. However, prior to conversion of these materials to useful products, pre-treatment of biomass is essential as it influences the energy utilization in the conversion process and feedstock quality. This chapter focuses on pre-treatment technology of palm-based agriculture waste prior to conversion to solid, liquid, and gas fuel. Pre-treatment methods can be classified into physical, thermal, biological, and chemicals or any combination of these methods. Selecting the most suitable pre-treatment method could be very challenging due to complexities of biomass properties. Physical treatment involves grinding and sieving of biomass into various particle sizes whereas thermal treatment consists of pyrolysis

S. Yusup (H) • M. M. Ahmad • Y. Uemura

Chemical Engineering Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia e-mail: drsuzana_yusuf@petronas. com. my

R. M. Ali

Management and Humanities Department, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak, Malaysia

A. S. Azmi

Department of Biotechnology Engineering, Faculty of Engineering, International Islamic University Malaysia,

Jalan Gombak, 53100 Kuala Lumpur, Malaysia

M. F. Mohamad

Biomass Processing Laboratory, Green Technology MOR,

Universiti Teknologi PETRONAS, Bandar Seri Iskandar,

31750 Tronoh, Perak, Malaysia

S. L. Lay

Kawasan Institusi Bangi, PETRONAS Research Sdn. Bhd.,

Lot 3288 & 3289, Off Jalan Ayer Itam, 43000 Kajang, Selangor, Malaysia

Z. Fang (ed.), Pretreatment Techniques for Biofuels and Biorefineries,

Green Energy and Technology,

DOI 10.1007/978-3-642-32735-3_17, © Springer-Verlag Berlin Heidelberg 2013 and torrefaction processes. Additionally biological and chemical treatment using enzymes and chemicals to derive lignin from biomass are also discussed.

Keywords Pre-treatment ■ Palm waste ■ Physical ■ Thermal ■ Biological ■ Chemical

17.1 Introduction

Energy from biomass sources accounts for 11 % of the total world energy supply [1]. Biomass of forestry, agricultural, and municipal wastes has become an alternative source for renewable energy to fulfill global energy demand which currently is sus­tained by the depleting fossil-based fuels, due to its abundance amount. As the world’s largest producer of palm oil, the availability of biomass from the palm oil industry provides an excellent opportunity for Malaysia to produce biofuels [2]. There are more than 3 million hectares of oil palm plantations in Malaysia and each year, about 90 million metric ton of renewable biomass in the form of trunks, fronds, shells, palm press fiber, and the empty fruit bunch (EFB) are produced [2]. Biomass is character­ized as a low energy density material, thus converting biomass into gaseous, liquid or solid-derived fuels and chemicals can be challenging. In general, biomass are characterized using several important properties such as calorific value (CV), bulk density, moisture content, ash content, and volatile and fixed carbon (FC) content. A lot of difficulties need to be overcome in order to utilize the biomass as fuel feed­stock; one of them is the limitations associated with the biomass fuel characteristics. Pre-treatment can enhance the properties of biomass prior to its effective conver­sion into fuels and chemicals. In this chapter, four pre-treatment methods including physical, thermal, biological, and chemical treatment are reviewed.

For example, direct comparison of solid biomass with coal, which is still the leading solid fuel for electricity and heat generation, frequently discloses inferior properties of biomass [3]. Typically, biomass has low-energy densities and high moisture content and is more tenacious (due to its fibrous nature). These properties give drawbacks such as lower combustion efficiencies and gasifier design limitations. Compared to coal, biomass varies in many properties; such as heating values, ultimate analysis (amounts of carbon, hydrogen, nitrogen, sulphur, and other impurities), and proximate analysis (FC, volatile material, ash content, and moisture content) [4]. Properties of biomass such as moisture and ash contents, volatile compounds, and particle size impose significant effect on the performance of a gasifier [5, 6]. Thus pre-treatment of biomass is crucial to increase its potentials for subsequent utilization as a solid fuel.

Biomass can be converted to liquid fuel through thermochemical or pyrolysis process. The liquid product is known as bio-oil. Bio-oil is a complex mixture of highly oxygenated compounds [7] and can be burnt efficiently in standard or slightly modified boilers [8, 9] and internal combustion engines [10, 11] at rates similar to those of commercial fuels. However, the combustion occurs at compromised heating values, that is, 40-50 % of that for hydrocarbon fuels. This is due to high water content (15-25 wt%) and high oxygen content (35-40 wt% on dry basis) that is detrimental for ignition. In addition, organic acids, mostly acetic and formic acid, in bio-oil are corrosive to common construction materials [12, 13]. The corrosiveness becomes severe at elevated temperature and with the increase of water content [14]. Moreover, solids (char) in bio-oil can cause clogging in injectors or corrode turbine blades. Over time, physicochemical changes will occur that further degrade the quality of the bio-oil. Presence of moistures will also decrease the biomass heating value. The density and viscosity of the liquid oil increase as the high molecular mass lignin fraction content increases. The increase in viscosity increases the pour point. The decrease in volatile aldehydes and ketones increases the flash point of the liquids.

Fermentation of biomass that is composed of cellulose, hemicellulose, lignin, and proteins, into bioalcohols quite often requires pre-treatment of biomass to break away the sugars contained within the matrix of cellulose fibers in plant cell walls. Pre­treatment also removes lignin from biomass, making it more digestable for enzymatic and microbial hydrolysis of lignocollulosic biomass [15]. Degradation of the lignin and hemicelluloses by the action of white-rot fungi is an aerobic process but there are some bacteria like Entrobacter lignoluticus SCF1 and rumen microorganisms with the lignin degradating capability under anaerobic condition [16, 17].