• Energy Research

Abstract The increase of fossil fuel burning to meet massive energy demands has resulted in major environmental problems. Extensive green house gas emissions and the depletion of non-renewable resources have promoted the use of hydrogen as an alternative energy source. Empty palm fruit bunches (EFB) are a type of agricultural waste that have a high potential for use as a sustainable biomass feedstock for hydrogen production. This study is focused on generation of biomass-derived hydrogen through catalytic biomass gasification using a modified CaO-based catalyst. The catalyst was prepared by adding 5% Ni as a primary dopant, followed by the addition of secondary dopants (La, K, Co, Fe) through a wet impregnation method, and characterised by X-ray diffractometer (XRD), N2 adsorption (BET) and Thermogravimetric Analysis (TGA). The synthesised catalysts were used as the primary catalysts in the reaction and were tested in temperature programmed gasification (TPG). The reaction was carried out in a partial oxygen environment by incorporating the biomass with the catalyst in a ratio of 1:2 from 50 to 900 °C and the product gases were detected by an online mass spectrometer. Interestingly, the addition of secondary dopants significantly increased the hydrogen production with notable changes in the CO2 absorption capacity of the catalyst. Moreover, K, Co and Fe dopants showed tar reforming properties and the highest hydrogen yield was observed with K as the added catalyst.

The current study is focused on controlling sulphur emissions by pre-treating coal to remove sulphur prior to combustion using the oxydesulphurisation technique. Three British coals were chosen for the study. Working with these coals gave a better insight to the oxydesulphurisation reactions for pyritic and organic sulphur. Effect of air and oxygen pressure in a fixed time interval on sulphur removal was studied by series of experimental runs at various temperatures. Heating value recoveries were significant. Increase in oxygen content is reported as a measure of carbon loss. The coal samples were analyzed according to British standard methods. Experimental results demonstrate that the sulphur removal was enhanced with the increase in air pressure, particularly up to 100 bars, with only a small decrease in calorific value at a particular temperature. Increasing temperature was witnessed to be more important in sulphur removal than increasing pressure.

A series of CdS/TiO2nanocomposites with different Cd to Ti molar ratio were synthesized from P25-TiO2nanopowder using microwave-assisted hydrothermal method. The as-produced powders were characterized by XRD, electron microscopy, EDX, and UV-Vis diffuse reflectance spectroscopy. The adsorption capacity and photocatalytic activity of the samples were investigated using methylene blue as a model pollutant. Sorption tests revealed that the adsorption of MB onto the samples obeys the Freundlich-Langmuir isotherm model. The sorption capacity decreased as follows:TiO2>TCd2>TCd1>TCd3>TCd4. The results of the photocatalytic tests under high-intensity discharge (HID) lamp revealed that CdS/TiO2powders with low Cd to Ti molar ratios exhibited much higher activities than P25-TiO2. The CdS/TiO2sample with 20% CdS/(TCd2) showed the most activity among all these samples. The results also show that the Cd to Ti molar ratio of the nanocomposite has a significant effect on the photodegradation of MB and the enhanced activities exhibited by the nanocomposites are because of the low rate of electron-hole recombination.

The amount of waste, associated waste disposal costs, and environmental contamination may be minimized by identifying effective recycling approaches. These promising approaches will also lead to the protection of natural resources and economic gains. One example of waste disposal maybe by using it as a filling material or as a pozzolanic material for the production of concrete. In this regard, this study proposes to partially replace cement with aluminum dross and fly ash, and partially replace natural sand with quarry dust. Aluminum dross, cement, sand, and quarry dust were used in a variety of proportions with a constant percentage of fly ash for the design of nine concrete mixtures. Aluminum dross was replaced by 5, 10, 15, and 20% of the cement mass. At first, the optimum replacement of aluminum dross without using quarry dust was determined at a constant percentage of fly ash-15% based on the strength results. Later, by introducing the optimum substitution of aluminum dross with cement and fly ash, the quarry dust was partially replaced at 10, 20, 30, and 40% of river sand to determine the overall optimum mix. The mechanical and durability characteristics of the concrete using the three mixtures were analyzed. It has been observed that the mechanical and durability characteristics of a concrete mixture incorporating a fly ash-15%, aluminum dross-10%, and quarry dust-20% are better than that of standard concrete. Production of concrete using industrial waste can minimize infrastructure construction costs and reduce environmental impacts.

Oil palm is one of the major economic crops in many countries. Malaysia alone produces about 47% of the world's palm oil supply and can be considered as the world's largest producer and exporter of palm oil. Malaysia also generates huge quantity of oil palm biomass including oil palm trunks, oil palm fronds, empty fruit bunches (EFB), shells and fibers as waste from palm oil fruit harvest and oil extraction processing. At present there is a continuously increasing interest in the utilization of oil palm biomass as a source of clean energy. One of the major interests is hydrogen from oil palm biomass. Hydrogen from biomass is a clean and efficient energy source and is expected to take a significant role in future energy demand due to the raw material availability. This paper presents a review which focuses on different types of thermo-chemical processes for conversion of oil palm biomass to hydrogen rich gas. This paper offers a concise and up-to-date scenario of the present status of oil palm industry in contributing towards sustainable and renewable energy.

Abstract Empty fruit bunches (EFBs) from the palm plantation sector are abundant agricultural waste products in Malaysia. Supercritical water gasification (SCWG) is a prominent way to convert high-moisture-content biomass such as EFBs into valuable end products. This investigation is focused on EFB conversion into hydrogen-rich products using SCWG (temperature = 380 °C and pressure ≈ 240 bar). Lignocellulosic model compounds (xylan, cellulose, and lignin) were used to study the degradation patterns and gas compositions under similar reaction conditions. The effect of the EFB/water ratio and the SCWG reaction time on the composition of the product gas was examined. Carbon gasification does not improve with increasing EFB/water ratio as well as with increasing reaction time caused by the thermally stable tar formation during reaction. The hydrogen concentration was found to be increased with reaction time along with raising the EFB/water ratio to 0.3 g (3.75 wt%). In addition, the possibility of using palm oil mill effluent as a reaction medium in comparison to deionized water was analyzed.

The abundance of chicken fats and skins as waste products from poultry industries have created a vital environmental issue. A feasibility study on converting chicken fats and skins waste into bio-oil via pyrolysis solvent-extraction was studied. The effects of pyrolysis temperature, solvent types, and pre-treatment process on the product yield were investigated. Subsequently, 60°C and hexane with pre-ultrasonication were selected due to higher bio-oil yield. The bio-oil gas chromatography-mass spectrometry analysis showed similar characteristics with gasoline and palm oil. Therefore, the abundance of chicken wastes has a potential to be converted into value-added bio-gasoline and, at the same time, improve the management of animal waste.

Three types of local Malaysian dolomites were characterized to investigate their suitability for use as tar-cracking catalysts in the biomass gasification process. The dolomites were calcined to examine the effect of the calcination process on dolomite’s catalytic activity and properties. The modifications undergone by dolomites consequent to thermal treatment were investigated using various analytical methods. Thermogravimetric and differential thermal analyses indicated that the dolomites underwent two stages of decomposition during the calcination process. The X-ray diffraction and Fourier-transform infrared spectra analyses showed that thermal treatment of dolomite played a significant role in the disappearance of the CaMg(CO3)2phase, producing the MgO-CaO form of dolomite. The scanning electron microscopy microphotographs of dolomite indicated that the morphological properties were profoundly affected by the calcination process, which led to the formation of a highly porous surface with small spherical particles. In addition, the calcination of dolomite led to the elimination of carbon dioxide and increases in the values of the specific surface area and average pore diameter, as indicated by surface area analysis. The results showed that calcined Malaysian dolomites have great potential to be applied as tar-cracking catalysts in the biomass gasification process based on their favorable physical properties.