**1. Introduction**

Waste-to-energy is gaining more and more attention as landfill costs and environmental concerns increase in many developed countries including Malaysia. Biomass from agricul‐ tural residues is one of the most important sources of renewable energy in Malaysia.The Na‐ tional Biofuel Policy, launched in 2006 encourages the use of environmentally friendly, sustainable and viable sources of biomass energy. Under the Five Fuel Policy, the govern‐ ment of Malaysia has identified biomass as one of the potential renewable energy. Malaysia produces at least 168 million tonnes of biomass, including timber and oil palm waste, rice husks, coconut trunk fibres, municipal waste and sugar cane waste annually. Being a major agricultural commodity producer in the region Malaysia is well positioned amongst the ASEAN countries to promote the use of biomass as a renewable energy source.

Combustion of agricultural residues is commonly used in industries for energy recovery. However, many researchers found that stand alone biomass firing is difficult to get high ef‐ ficiency [1-5]. Thus, co-firing biomass with coal in industrial and utility boilers could offer an alternative approach with improved combustion efficiency, lower-cost and reduced risk technology. Significant co-combustion potential for biomass and waste materials exists in all European Union (EU) countries and this is mirrored on a worldwide basis, creating a signifi‐ cant market for equipment and services. Fluidized bed combustion (FBC) technology has al‐ ready proven highly efficient, economic and environmentally sound combustion of a wide variety of fuels in comparison conventional combustors. Hence, with the current demands in electricity and with the recent developments in biomass energy, co-combustion of bio‐

properly cited.

© 2013 Wan Ab Karim Ghani and Bahari Alias; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is © 2013 Wan Ab Karim Ghani and Bahari Alias; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

mass with coal must be recognized as one of the most important source of energy for the foreseeable future.

**•** highly responsive to rapid changes in heat demand).

**•** The fuel supplied can be either wet or dry

ing in a high dust load in the flue gas;

pressed

**1.3. Combustion studies**

phenomena occur namely [20-22]:

and beyond

**•** Large solid–gas exchange area by virtue of the small solids grain size

**•** having different sizes, shapes, moisture contents and heating values.

Sets against these advantages are the following disadvantages:

**•** Possibility of de-fluidization due to agglomeration of solids;

teristics of biomass residues and their co-combustion with coal in FBC.

be evolved and can be burnt at or beyond the particle.

**•** High heat-transfer coefficients between bed and the heat exchanging surfaces; the

**•** intense motion of the fluidized bed makes it possible to combust a wide range of fuels

Sustainable Power Generation Through Co-Combustion of Agricultural Residues with Coal in Existing Coal Power

Plant

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http://dx.doi.org/10.5772/52566

**•** The high heat capacity of the fluidized bed permits stable combustion at low tempera‐ tures (i.e. 850°C), so that the formation of thermal and prompt nitrogen oxides is sup‐

**•** Solid separation equipment required because of solids entrained by fluidizing gas result‐

Fluidized bed combustion of alternative solid fuels (including biomass) are attractive as a result of the constantly increasing price of fossil fuels, the presence of high quantities of wastes to be disposed of and global warming issues. Extensive experimental investigation has been carried out to date on the feasibility and performance of different biomass fuels FB combustion such as rice husk [10-13], animal waste [14-15], municipal solid waste (MSW) [16-19] and Refuse Derived Fuel (RDF) [5]. In whatever form biomass residues are fired (loose, baled, briquettes, pellets), a deeper understanding of the combustion mechanisms is required in order to achieve high combustion efficiency and to effectively design and oper‐ ate the combustion systems. The combustion properties and their effect on combustion mechanisms are all important information required to understand the combustion charac‐

In general when a single coal or biomass particle enters a fluidised bed furnace, then three

**•** Heating up and drying – the fuel particle temperature will rise to its ignition temperature

**•** Devolatilization (pyrolysis) – for a short period of time (<10 second), volatile matter will

**•** Char oxidation – the remaining solid combustible matter (mostly carbon), will be oxidised relatively slowly with the evolution of heat until only incombustible ash remains.

Fuel properties and combustion operating parameters significantly influenced the combus‐ tion efficiency and emissions. Armesto et al (2002) has stated that the bed temperature has

#### **1.1. Biomass as potential renewable resources**

A recent study shows that Malaysia has been one of the world's largest producers and ex‐ porters of palm oil for the last forty years. The Palm Oil industry, besides producing Crude Palm Oil (CPO) and Palm Kernel Oil, produces Palm Shell, Press Fibre, Empty Fruit Bunch‐ es (EFB), Palm Oil Mill Effluent (POME), Palm Trunk (during replanting) and Palm Fronds (during pruning). Almost 70% of the volume from the processing of fresh fruit bunches (FFB) is removed as waste.Malaysia has approximately 4 million hectares of land under oil palm plantation. Over 75% of total area planted is located in just four states, Sabah, Johor, Pahang and Sarawak, each of which has over half a million hectares under cultivation. The total amount of processed FFB was estimated to be 75 million tons while the total amount of EFB produced was estimated to be 16.6 million tons. Around 58 million tons of POME is produced in Malaysia annually, which has the potential to produce an estimated 15 billion m3 of biogas can be produced each year [6].

Rice husk is another important agricultural biomass resource in Malaysia with good potential for power cogeneration. An example of its attractive energy potential is biomass power plant in the state of Perlis which uses rice husk as the main source of fuel and generates 10 MW pow‐ er to meet the requirements of 30,000 households. The US\$15 million project has been under‐ taken by Bio-Renewable Power Sdn. Bhd in collaboration with the Perlis state government, while technology provider is Finland's Foster Wheeler EnergiaOy. Under the EC-ASEAN Co‐ generation Program, there are three ongoing Full Scale Demonstration Projects (FSDPs) – Titi‐ Serong, Sungai Dingin Palm Oil Mill and TSH Bioenergy – to promote biomass energy systems in Malaysia. The 1.5MW TitiSerong power plant, located at Parit Buntar (Perak), is based on rice husk while the 2MW Sungai Dingin Palm Oil Mill project make use of palm kernel shell and fibre to generate steam and electricity. The 14MW TSH Bioenergy SdnBhd, located at Ta‐ wau (Sabah), is the biggest biomass power plant in Malaysia and utilizes empty fruit bunches, palm oil fibre and palm kernel shell as fuel resources [7].
