• Energy Research

Release of green house gases (GHGs) from landfills as a result of ineffective management of those landfills is a serious environmental problem especially in developing countries. The landfill gas (LFG) thus released is a potential resource that can be converted to renewable energy. LFG is made up majorly of methane and carbon dioxide and produced by anaerobic biodegradation processes of municipal solid waste in landfills. This study estimates the amount of this methane emitted from landfills and its potential economic benefits. Using the Intergovernmental Panel on Climate Change (IPCC) methodology, in 2002, methane emission of 251,000 tonnes per year was estimated for Peninsular Malaysia based on 16,988 tonnes per day of municipal solid waste generated. This can generate 1.5 billion kWh of electricity per year worth over RM 450 million (US$141 million). In addition, this leads to carbon dioxide reduction of 5,271,000 tonnes per year equivalent to carbon credit of RM 222 million (US$69 million). Therefore, the exploration of this resource, besides the economic benefits helps in reducing the dependence on depleting fossil fuel and hence mitigating global warming.

Landfill gas (LFG) is essentially greenhouse gas (GHG) composed predominantly of methane and carbon dioxide produced from the anaerobic biodegradation of municipal solid waste in landfills. The amount of gas produced can be estimated using the Intergovernmental Panel on Climate Change methodology. Most sanitary landfills flare this potential renewable energy source, which is an unfortunate waste of a valuable resource. This study develops an optimization model for effective LFG utilization as a sustainable energy source based on economic and environmental considerations. The mixed integer linear programming model developed was applied to Seelong Sanitary Landfill, Malaysia, and led to profits 7.6 times higher than those currently gained. This enormous increase is due to the incorporation of renewable energy production in the new plan. In addition, the combined heat and power generation proposed is 2420 tons of oil equivalents, which is 0.0035% of the total energy production of Malaysia. Similarly, the LFG utilization leads to a national GHG reduction of 0.007%. Implementing this at the 14 sanitary landfills in the country will go a long way towards broadening the energy base while simultaneously reducing the carbon footprint of the nation. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 289–296, 2015

The esterification of oleic acid in the presence of magnetic ionic liquid, 1-butyl-3-methylimidazolium tetrachloroferrate ([BMIM][FeCl4]) at reaction temperature of 65 °C has been investigated. Artificial neural network-genetic algorithm (ANN-GA) was used to simultaneously optimized methyl oleate yield and oleic acid conversion for the reaction. It was found that optimum responses for both yield and conversion were 83.4%, which can be achieved using molar ratio methanol–oleic acid of 22:1, catalyst loading of 0.003 mol and reaction time at 3.6 h. Esterification of oleic acid at optimum condition using recycled [BMIM][FeCl4] registered not much loss in catalytic activity after six successive runs. Kinetic study indicated that the reaction followed a pseudo-first order reaction, with activation energy and pre-activation energy of 17.97 kJ/mol and 181.62 min−1, respectively. These values were relatively low compared to homogeneous or heterogeneous catalysts for esterification of oleic acid. Thus, [BMIM][FeCl4] is a promising new type of catalyst for conversion of high free fatty acid (FFA) feeds to biodiesel.

This paper is focused on the design of a bubbling fluidized bed gasifier (BFBG) for EFB briquette gasification. The annual production of palm oil in Malaysia generates large quantities of lignocellulosic biomass which can be converted into clean, sustainable energy for the future. Hence, the prospect of valorising palm waste using biomass gasifiers presents a viable option for energy production. The fluidized bed gasifier (FBG) is considered the most suitable reactor for biomass gasification due excellent mixing, efficient heat temperature control and tolerance for fuels. Consequently, the proposed design of the bubbling fluidized bed gasifier for EFB briquette gasification will consist of three main parts; feeding zone, gasification zone and the effluent gas zone for syngas production. The results of feedstock physicochemical properties such as bulk density, particle size, the bed hydrodynamic and fluidization parameters for gasification used in the design of the gasifier are presented in this paper.

Combustion behaviour of municipal solid waste in a fluidised bed was studied. The effect of fluidisation number and total air factor on the combustion behaviour of municipal solid waste of high moisture content in a fluidised bed combustor was investigated. The first part of the combustion study was carried out at fluidisation numbers ranging from 5 to 7 Umf with a fixed Primary Air Factor (AF) of 0.8. Results show that the optimum fluidisation number is 5 Umf in which the bed temperature sustained longer. The second part of the study dealt with the effect of secondary air on the bed combustion behaviour conducted at 5 Umf. The chosen range of secondary air factor is 0–0.6. It is revealed that the addition of secondary air has no effect on the bed combustion.

The energy insecurity from oil and natural gas and increased CO2 emission from fossil fuels is driving societies to look for sustainable and renewable energy supply. The huge coal resources can serve as a potential source for fuels. Bio-energy from biomass has been recognized as renewable energy to reduce CO2 emission. Although fast pyrolysis has emerged as the most promising technology to convert organic materials to liquid fuels at shorter duration but it still faces some technical challenges in improving product yield, its quality and process energy efficiency. Microwave assisted pyrolysis of coal and biomass in the presence of microwave absorber provides distinctive environment to resolve these challenges. The microwave absorber can indirectly heat coal and biomass particles which are relatively microwave transparent and influence product yield and its quality by contributing as a catalytic precursor. The microwave heating of coal or biomass particles with microwave absorber shows efficient heating and sufficient contact of volatile or gas phase species with specific microwave absorber can improve fuel quality.

The reduction of oil resources and increasing petroleum price has led to the search for alternative fuel from renewable resources such as biodiesel. Currently biodiesel is produced from vegetable oil using liquid catalysts. Replacement of liquid catalysts with solid catalysts would greatly solve the problems associated with expensive separation methods and corrosion problems, yielding to a cleaner product and greatly decreasing the cost of biodiesel production. In this paper, the development of solid catalysts and its catalytic activity are reviewed. Solid catalysts are able to perform trans-esterification and esterification reactions simultaneously and able to convert low quality oils with high amount of Free Fatty Acids. The parameters that effect the production of biodiesel are discussed in this paper. © 2012 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Abstract Combustion behavior of mixed solid waste in a fluidized bed was studied. Bed, surface and freeboard temperatures were monitored continuously for that purpose. The effect of fluidization number and air factor on the combustion behavior of mixed solid waste of high moisture content in a fluidized bed combustor was investigated. Mixed solid waste was used as a sample which was formulated from four major waste compositions found in Malaysia namely food, paper, plastic and vegetable waste (green). Combustion study was carried out in a rectangular fluidized bed with sand of mean particle size of 0.34 mm as a fluidization medium. The range of fluidization numbers investigated was 3–11 U mf . The first part of the combustion study was carried out at stoichiometric condition. Results showed that the best fluidization number was 5 U mf in which the bed temperature was sustained in a much longer period. The second part of the study dealt with the effect of air factor on the combustion behavior conducted at 5 U mf . The chosen range of air factor was 0.4–1.2. It was revealed that the best air factor was in the range of 0.8–1. Energy balance was also performed to determine the thermal efficiency of the combustion. It was concluded that the thermal efficiency was significantly increased at higher air factor.

Discharge of Green House Gases (GHGs) and the management of municipal solid waste (MSW) continue to be a major challenge particularly in growing economies. However, these are resources which can be converted to green energy. Landfill gas which is essentially methane (50–55%) and carbon dioxide (40–45%) (both GHGs) is released from MSW by biodegradation processes. The estimation of this methane and its economic and environmental benefits for environmental sustainability are the objectives of this study. Methane emission from MSW disposed of in landfills was estimated using Intergovernmental Panel on Climate Change (IPCC) methodology. From the study, based on 8,196,000 tonnes MSW generated in Peninsular Malaysia in 2010, anthropogenic methane emission of about 310,220 tonnes per year was estimated. This was estimated to generate 1.9 billion kWh of electricity year−1 worth over RM 570 million (US$190 million). In addition, this leads to carbon dioxide reduction of 6,514,620 tonnes year−1 equivalent to carbon credit of over RM 257 million (US$85 million). These results were also projected for 2015 and 2020 and the outcomes are promising. Therefore, the exploration of this resource, besides the economic benefits helps in reducing the dependence on the depleting fossil fuel and hence broadening the fuel base of the country.