Life cycle assessment of two palm oil production systems

In 2009 approx. 40 Mt of palm oil were produced globally. Growing demand for palm oil is driven by an increasing human population as well as subsidies for biodiesel and is likely to increase further in coming years. The production of 1 t crude palm oil requires 5 t of fresh fruit bunches (FFB). On average processing of 1 t FFB in palm oil mills generates 0.23 t empty fruit bunches (EFB) and 0.65 t palm oil mill effluents (POME) as residues. In this study it is assumed that land use change does not occur. In order to estimate the environmental impacts of palm oil production a worst and a best case scenario are assessed and compared in the present study using 1000 kg of FFB as functional unit.The production and treatment of one t FFB causes more than 460 kg CO_2eq in the worst case scenario and 110 kg CO_2eq in the best case scenario. The significant greenhouse gas (GHG) emission reduction is achieved by co-composting residues of the palm oil mill. Thus treating those residues appropriately is paramount for reducing environmental impacts particularly global warming potential (GWP) and eutrophication potential (EP).Another important contributor to the EP but also to the human toxicity potential (HTP) is the biomass powered combined heat and power (CHP) plant of palm oil mills. Frequently CHP plants of palm oil mills operate without flue gas cleaning. The CHP plant emits heavy metals and nitrogen oxides and these account for 93% of the HTP of the advanced palm oil production system, of which heavy metal emissions to air are responsible for 79%. The exact emission reduction potential from CHP plants could not be quantified due to existing data gaps, but it is apparent that cleaning the exhaust gas would reduce eutrophication, acidification and toxicity considerably.     

Electrical and optical properties of F-doped textured SnO2 films deposited by APCVD

This paper presents the structural, electrical and optical properties of transparent conducting F-doped textured SnO₂ films prepared by atmosphere pressure chemical vapour deposition (APCVD). Polycrystalline SnO₂:F films having a variable preferred orientation have been obtained with resistivity as low as 5 × 10⁻⁴ Ωcm, with carrier concentrations between 3.5 × 10²⁰ and 7 × 10²⁰ cm⁻³, and Hall mobilities from 15.7 to 20.1 cm²/V/s. The average transmittance (including diffusion transmittance) is as high as 94% in the wavelength range of the visible spectrum and the maximum infrared reflectance reaches 92% for a film 655 nm thick. The figure of merit ƒ_TC = T10/_sh, (7.12 × 10⁻² S) of these films is the highest amongst the results reported on doped SnO₂ films.     

Out of the cell performance of reforming catalysts for direct molten carbonate fuel cells (DMCFC)

Nickel catalysts supported on commercial MgO and LiAlO₂ have been tested and compared in the methane steam reforming reaction at temperatures ranging from 798 to 923 K and GHSV from 5.4 × 10⁶s⁻¹ to 5.4 × 10⁸s⁻¹. Initial molar ratio of the reactants, R = P_H2O/P_CH4 was 2.54. Results of the influence of the catalyst reduction temperature have been reported. Preliminary results of the reaction kinetic analysis, adopting first order pseudohomogeneous model, are given. The suitability of using these catalysts into the molten carbonate fuel cells (MCFC), to generate hydrogen directly by the methane steam reforming, is discussed.     

Combined heat and mass transfer by natural convection at horizontal cylinder electrodes

Simultaneous heat and mass transfer in free convection at horizontal cylinder electrodes has been investigated experimentally using the electrochemical limiting diffusion current technique. The convective flow patterns occuring have been observed using Schlieren photography. The results confirmed the use of a combined Grashof number (GR_m) to account for thermal and concentration buoyancy effects. Various combinations of electroactive species concentration, cylinder diameter and cylinder surface temperature have been used. Results have been successfully correlated by the equations , 7×10⁷ < GR_mSc< 4×10⁹ and , 4×10⁹ mSc<10¹¹ The experiments cover the range of mass transfer and heat transfer Grashof numbers 3.64×10⁴ m <3.02×10⁶, 5.67×10⁴ h <6.55×10⁶     

Impact of air ions on mass transfer from liquids

Evaporation rates and drying times of liquids exposed to relatively high fluxes of unipolar air ions of either sign, produced by corona electrodes, were studied with a beta-ray gauge apparatus. Liquids of constant volume, exposed to air ions, dried 1.72 to 4.80 times faster than the corresponding control liquids under the same laboratory conditions. An analysis of the time-transmission curves from the beta-ray gauge showed mass transfer rates of 1.90 × 10⁻³ and 8.5 × 10⁻³ g min⁻¹ for control and treated (2.44 × 10¹² positive ions cm⁻² s⁻¹) water, respectively. Air ions were observed to cause circulatory and vibrational movements in the treated liquids. These movements contributed to the enhancement in the mass transfer rates from organic and inorganic liquids studied. Polarity of the molecules may also determine the rapidity at which a liquid will evaporate when exposed to a high flux of air ions.     

Assessment of oil and natural gas resources in the Gulf Cooperation Council countries

This paper deals with the assessment of oil and natural gas resources in the Gulf Cooperation Council. Currently, the reserves of oil and natural gas are estimated at 461.70 × 10⁹ barrels and 615.58 × 10¹² SCF, respectively. Data are given and analyzed on reserves and production for the period 1978–1989.     

Preparation and properties of transparent conducting zinc oxide and aluminium-doped zinc oxide films prepared by evaporating method

Undoped and aluminium-doped zinc oxide films have been prepared by thermal evaporation of zinc acetate [Zn(CH₃COO)₂ 2H₂O] and aluminium chloride [AlCl₃] onto a heated glass substrate. The structural and optoelectrical properties of the films have been studied. The effects of heat treatment for the as-deposited films in air and vaccum are investigated. Highly transparent films with conductivity as low as 2×10⁻³ Ω cm can be produced by controlling the deposition parameters. The electron carrier densities are in the range 0.2–7×10¹⁹ cm⁻³ with mobilities of 22–58 cm² V⁻¹ s⁻¹.     

Prospects for geothermal energy applications and utilization in Canada

Like the sun, the earth is a vast energy source. The utilization of this geothermal furnace is still in its infancy, the heat flow from the mantle to the surface (9 × 10⁻¹ cal/cm²/min; 0.063 W/m²) is the energy equivalent to 2 × 10¹¹ barrels of oil per yr (3 × 10¹⁰ tons or about fourfold greater than the present yearly total world energy consumption). Although today only local hot spots yielding dry and wet steam, and shallow hot-water sites are used economically, future technology may well lead to a much greater utilization. This will be done through additional imaginative and sophisticated exploitation of available regions of dry hot rock, geopressure-geothermal fields, and even deep areas of significant heat flow. Such potential utilization of geothermal resources should provide for relatively pollution-free, steam-generated electrical power, steam and hot-water for home and industry, mineral and chemical by-products, as well as numerous uses where hot water is required in agriculture, horticulture, fisheries, mining, pulp and paper and other industries. Canadian developments in these areas are still relatively dormant. The problem areas are not of a technological nature but rather of an institutional type in passing a geothermal act that would provide the incentives for exploration and economical development.     

Energy overview for the sultanate of oman

Since 1967, exporting crude oil has been the leading hard-currency earner for Oman: 9×10⁵ barrels of crude oil per day being extracted in 1997. The total remaining oil reserves, which can be harnessed economically now, amount to approximately 5.2×10⁹ barrels, but this commercially-available resource is expected to be depleted completely by the year 2015. The second most important source of energy in the country is natural gas: present economically-harnessable reserves are approximately 724×10⁹ Nm³. In 1994, the amount extracted was merely 2.4×10⁹ Nm³. This resource is expected to be exhausted by the year 2064. From 1990 to 1995, the Government-run electricity-generation power-capability rose from 1277 to 1642 MW: the peak demand has grown simultaneously by 59%. The total-power generation in 1995 was 6500 GWh, while the annual consumption was 6173 GWh; the domestic sector accounting for approximately 60% of the total consumption. The rate of energy consumption pattern is seasonal in nature, with the mid-summer electric demand being nearly triple that of mid-winter. Private cars accounted for 54% of the total number of vehicles in Oman in 1994, and this number is rising rapidly. The associated freedom of choice to use the private car in order to satisfy the desires for increased mobility and privacy will not be sustainable in the long term.     

Electrochemical properties of the LaNi3.55Mn0.4Al0.3Co0.4Fe0.35 hydrogen storage alloy

The electrochemical properties of LaNi_3.55Mn_0.4Al_0.3Co_0.4Fe_0.35 hydrogen storage alloy have been studied through chronopotentiometric, chronoamperometric and cyclic voltammogram measurements. The maximum capacity value obtained was 265 mAh g⁻¹ at rate C/6 and the capacity decrease was recorded by 1.5% after 30 cycles. The values of the hydrogen diffusion coefficient D_H obtained through cyclic volammogram and chronoamperometric techniques were, respectively, 7.01 × 10⁻⁸ cm² s⁻¹ and 4.23 × 10⁻¹¹ cm² s⁻¹.     

Estimation of convective mass transfer in solar distillation systems

In this article a thermal model has been developed to determine the convective mass transfer for different Grashof Number range in solar distillatiOn process. The model is based on simple regression analysis. Based on the experimental data obtained from the rigorous outdoor experimentation on passive and active distillation systems for summer climatic conditions, the values of C and n have been calculated. The modified values of C and n for Nu=C(GrPr)ⁿ, are proposed as C=0.0322; N=0.4114 for 1.794 × 10⁶6 in a passive solar still and C=0.0538; N=0.383 for 5.498 × 10⁶6 in an active solar still. The percentage deviation between experimental and theoretical results are found within an accuracy of 12%.     

The liquid flow in multi-stage flash evaporators

In an attempt to reach a quantitative understanding of the interaction between the fluid mechanics and flash evaporation in a stage of a multi-stage flash (MSF) evaporator, and in horizontal free-surface streams in general, a numerical analysis is performed, as a first step, of two-dimensional turbulent isothermal flow of a liquid in a flash chamber (stage) with and without a baffle (sill) placed downstream of the inlet orifice. Experiments are also performed, and validate the model successfully in the range of flows of 4.3 × 10⁵−8.7 × 10⁵ kg h⁻¹ (m width)⁻¹ and liquid level of 0.4 m, conditions typical to MSF evaporators. The baffle plate is found to serve well in propelling the entering liquid to the free surface and in generating low-pressure regions, primarily near the stream line rising from the top edge of the baffle, both effects promoting evaporation rates. The interstage orifice coefficient is found to be practically independent of the liquid superheat, temperature, and mass flow rate.     

Heat transfer of a plate in a liquid flow

The paper presents results of the experimental investigation of heat transfer of a plate in a flow of air, water and transformer oil at different directions of heat flow over the range of Re_f numbers from 2 × 10⁴ to 3 × 10⁷ and that of Pr_f—from 0.701 to 380. Formulae were obtained to calculate heat transfer of a plate in a liquid flow.     

Effect of rare earth oxides for improvement of MCFC

The solubility of rare earth metal oxides and their effect on the NiO solubility have been discussed to stabilize the cathode of molten carbonate fuel cells. The solubility of Ho, Yb, and Nd oxides were 4.4 × 10⁻⁴, 3.4 × 10⁻⁴, and 1.3 × 10⁻³ (mole fraction) at 923 K, respectively. The solubilities of NiO in (Li_0.52/Na_0.48)₂CO₃ with the saturated Ho, Yb, and Nd were 1.57 × 10⁻⁵, 1.41 × 10⁻⁵, and 9.5 × 10⁻⁶, respectively. Among these three, Nd, which has the highest solubility in the carbonates, reduced the NiO solubility most; although, the La reduced the NiO solubility more than Nd.

The logarithm of the solubility of the rare earth metal oxides has a linear relation to the Coulomb force ratio between the rare earth metal and the alkaline metal. Following this relation, the La should have the highest solubility among all the lanthanides. The basicity which NiO solubility closely relates has a linear relationship to the Coulomb force parameter of the melts. Based on these two models, the La would be the best additive to reduce the NiO solubility in Li/Na eutectic carbonate melt, among all the lanthanides.     

Flue-gas desulphurisation products from Polish coal-fired power-plants

Many desulphurisation installations were constructed in the Polish power industry in recent years, so SO₂ emissions were reduced by a half to 1.04×10⁶ tonnes in 2000, while SO₂ capture increased to 43.7% in 2000. FGD gypsum, obtained by the most important wet-limestone desulphurisation method, is recognised as a substitute for natural gypsum. Its production in Poland started in 1994, and amounted to 1.1×10⁶ tonnes in 2000. It is currently fully used in gypsum binders, plasters and plasterboard manufacture, as well as an additive in the production of Portland cement. Other FGD materials—obtained in dry and semi-dry methods of desulphurisation—have variable phase and chemical compositions, so they do not find industrial applications and are mainly stockpiled in underground mines or open pits. The sulphate-calcium ashes from an AFBC process will probably be used in the cement industry simultaneously as a pozzolanic additive and setting-time regulator, provided that their compositions are constant. Their total supply amounted to ca. 1.5×10⁶ tonnes in 2000, but within 5 years, it should achieve 4.0×10⁶ tonnes.     

Synthesis and characterization of CuInSe2 thin films from Cu, In and Se stacked layers using a closed graphite box

Various techniques have been used to produce CuInSe₂ but the problem of producing films with the desired properties for efficient device fabrication over large areas has always persisted. The Stacked Elemental Layer (SEL) technique has been demonstrated as a method for producing films over a large area, but the films normally annealed in vacuum or in Se ambient, mostly exhibited poor morphology with small grain sizes which result in poor devices. A method of synthesizing CuInSe₂ films by annealing or selenization of the Cu, In and Se elemental layers using a closed graphite box was developed. SEM, EDX, XRD, spectrophotometric and Hall measurements were used to characterize all annealed films. Results have shown single phase chalcopyrite films with improved crystal sizes of about 4 μm The film composition varied from Cu-rich to In-rich with electrical resistivities of 10⁻³ to 10⁴ Ωcm, cattier concentrations of 5 × 10¹⁵ to 10¹⁷ cm⁻³ and mobilities of 0.6 to 7.8 cm² V⁻¹ s⁻¹ An energy band gap of 0.99 eV and 1.02 eV was obtained for a Cu-rich and near stoichiometric In-rich films respectively. Heterojunction devices using the structure ZnO/CdS/CuInSe₂ were fabricated with electrical conversion efficiencies of 6.5%.     

Kinetics of the NCO radical reacting with atoms and selected molecules

Rate constants for the reaction of isocyanate radicals (NCO) in its electronic ground state ( ²Π) with oxygen atoms were determined at 2.5 Torr total pressure in the temperature range 302–757 K. Excimer laser photolysis (ELP) of chlorine isocyanate (ClNCO) produced NCO radicals detected by laser-induced fluorescence (LIF). The reaction NCO + O exhibits a negative temperature dependence, described by the two-parameter equation: k_NCO+O(T) = (4.3_−2.2^+3.2) × 10⁻⁸ × T^{−1.14_−0.12+0.08} cm³ molecule⁻¹ s⁻¹. Measurements at 298 K and total pressures of 2.5 and 9.9 Torr, respectively, indicated a slight pressure dependence. For the reaction of NCO radicals with hydrogen atoms, the rate constant k_NCO+H = (2.2 ± 1.5) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹was obtained at 298 K and a total pressure of 2.6 Torr for the first time by a direct measurement. From a single measurement k = (3.8 ± 1.6) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ was determined at 548 K and 2.4 Torr total pressure. In addition, rate constants for the reactions of NCO radicals with molecular oxygen (O₂), carbon dioxide (CO₂), molecular hydrogen (H₂), and carbon monoxide (CO), which is a dissociation product of CO₂ in a microwave discharge, were measured at two different temperatures. At room temperature these reactions were slow and at the detection limit of the ELP/LIF technique. However, at elevated temperatures at least the rate constants of the reactions NCO + O₂ and NCO + H₂ become significantly larger and, therefore, should be taken into account, when modeling combustion processes under certain conditions.     

Dynamic modeling and simulation of a palm wastes boiler

A state-space dynamic model for a palm wastes boiler is being developed and simulated. The unique feature of this boiler is that it uses wastes in the form of fiber and shell from the palm oil processing as its fuels. Specific characteristics of oil palm waste boilers are non-uniform fuel feed, compositions, sizes and moisture content of the fuel. These features introduce additional dimensions to the difficulty of boiler control. The superheated steam produced is used to generate electricity, which drives numerous motors and other equipment for palm fruit processing thus causing severe interactions between the power plant and other parts of the mill. The main work of this paper is the development of a dynamic model and simulation of the boiler. The boiler unit can be divided into several sections for analysis viz., the furnace, superheater, drum, risers, and downcomer. A tenth-order, physical, linearized process model was developed. The linearized model consists of ten first-order simultaneous equations and is represented by a (10 x 10) state matrix and (4 x 10) input matrix in the state space form.     

Performance of low bandgap thermophotovoltaic cells in a small cogeneration system

In recent years there has been significant progress in fabrication of low bandgap thermophotovoltaic (TPV) devices, such as InGaAsSb, InGaAs and GaSb cells. However, only limited data are available in the literature with respect to the performance of these TPV cells in combustion-driven radiant sources. In this study, power generation using InGaAsSb TPV cells has been investigated in a gas-fired home heating furnace. The radiant power density and radiant efficiency of a gas-heated radiator were determined at different degrees of exhaust heat recuperation. Heat recuperation is shown to have a certain effect on combustion operation and radiant power output. The electric output characteristics of the InGaAsSb TPV devices were investigated under various operating conditions. An electric power density of 5.4×10³ W m⁻² was produced at a radiator temperature of 1463 K for the small cogeneration system. The cell short circuit density was observed to be greater than 1×10⁴ A m⁻² at a radiator temperature of 1203 K. Furthermore, the design aspects of combustion-driven TPV systems have been discussed. It is shown that development of a special combustion device with high conversion level of fuel chemical energy to useful radiant energy is required, to improve further the system efficiency.     

High temperature rate coefficient for the reaction of O(P) with H2 obtained by the resonance absorption of O and H atoms

The reaction of O(³P) with H₂ has been studied behind reflected shock waves in the temperature range of 1713–3532K at total pressures of about 1.4–2.0 bar by Atomic Resonance Absorption Spectroscopy using mixtures of N₂O and H₂ highly diluted in Ar. The O atoms were generated by the fast thermal decomposition of N₂O and the reaction with H₂ was followed by monitoring the time dependent O and H atom concentrations in the postshock reaction zone. For the experimental conditions chosen, the measured O and H atom concentrations were primarily sensitive to the well-known N₂O dissociation and to the studied reaction and hence its rate coefficient could be deduced. The measured rate coefficient data are fitted by the least-squares method to obtain the following three parameter expression: K₄=3.72×10⁶(T/K)^2.17exp(−4080K/T)cm³ mol⁻¹8⁻, which is in excellent agreement with the recent ab initio calculations for the rate coefficient of this reaction in the overlapping temperature range. The present result is also compared to the experimental results reported by earlier investigators.