Economic feasibility analysis of a solar energy and solid oxide fuel cell-based cogeneration system in Malaysia

The current study presents a concept of a cogeneration system integrated with solar energy and solid oxide fuel cell technology to supply electrical and thermal energy in Malaysia. To appraise the performance, the system is analysed with two case studies considering three modes of operation. For the case-1, typical per day average electricity and hot water demand for a single family have been considered to be 10.3 kWh and 235 l, respectively. For the case 2, electricity and hot water demand are considered for the 100 family members. Energy cost, payback period, future economic feasibility and the environmental impact of the system are analysed for both cases using an analytical approach. The overall system along with individual component efficiency has been evaluated, and the maximum efficiency of the overall system is found to be 48.64 % at the fuel cell operation mode. In the present study, the proposed system shows 42.4 % cost effectiveness at higher load. Energy costs for case-1 and case-2 have been found to be approximately $0.158 and $0.091 kWh^?1, respectively, at present. Energy costs are expected to be $0.112 and $0.045 kWh^?1 for the case-1 and case-2, respectively, considering future (i.e. for the year 2020) component cost.     

Impact of including land-use change emissions from biofuels on meeting GHG emissions reduction targets: the example of Ireland

The greenhouse gases (GHG) emissions from land-use change are of particular concern for land-based biofuels. Emissions avoided by substituting fossil fuels with biofuels may be offset by emissions from direct and indirect land-use changes (LUC). There is an urgent need to investigate what impact land-use change emissions may have on the expansion of bioenergy and biofuels, in the context of EU mitigation policies. This paper focuses on Ireland, which faces a number of challenges in delivering its renewable energy and GHG reduction targets. The Irish TIMES energy systems model was used to assess the impact of a range of land-use change emissions’ levels on the evolution of Ireland’s low-carbon energy system. A reference scenario was developed where LUC is ignored and Ireland achieves a least-cost low-carbon energy system by 2050. If high indirect land-use change (ILUC) emissions are included, this results in a decrease by 30 % in bioenergy and a 68 % increase in marginal abatement costs by 2050. Hydrogen is used instead of bioenergy in the freight sector in this scenario, while private cars are fuelled by renewable electricity. If GHG emissions from ILUC were considered less severe, indigenous grass biomethane becomes the key biofuel representing 31 % of total bioenergy consumption. This is in line with recent research in Ireland of the key role that grass biomethane can play.     

Biogas production from energy crops in northern Greece: economics of electricity generation associated with heat recovery in a greenhouse

Herein a techno-economic assessment was performed on an energy-crop-based biogas plant coupled with a greenhouse for utilizing thermal energy produced by cogeneration. Seven energy crops were evaluated: triticale, maize, alfalfa, sunflower, clover, barley and wheat. According to the evaluation, triticale was the most competitive energy crop under selected climate conditions for northern Greece. Although maize displays higher biomass yield and biogas potential than the drought-resistant crop triticale, it has high irrigation demand that contributes significantly to total production costs. For a triticale-based biogas production to become economically feasible, agricultural arable area larger than 500 ha, or biogas plant size larger than 1000 kW_el, is required. However, with public funding, biogas production becomes feasible at smaller area (>250 ha) or biogas plant size (>500 kW_el). The inclusion of a greenhouse into the design of the biogas plant contributes positively to the economic viability of the entire system. Under this scenario, greenhouse financial income accounts for about 17–18% of total income. Results of a sensitivity analysis suggest that the selection of an appropriate energy crop for biogas production should be based principally on both digestibility (specific methane yield) and biomass yield per hectare, these factors being more critical than biomass production costs.     

Optimal design of an absorption chilled water storage air conditioning system driven by waste heat

In order to meet both economic and energy requirements, this study has proposed an optimal design to minimize the sum of the initial and operation energy costs for a 1200 refrigeration ton chiller and 12 water storage tanks in an absorption chilled water storage air conditioning system. Various power consumption calculation methods for the main devices are included to predict the performance of this equipment under different operating conditions. In addition, the performance curves of the water storage tank under the storage and discharge modes are calculated using Fluent software. The article uses five control strategies for a cooling tower along with three hot water inlet temperatures of a generator to simulate the optimal design of a system. The results show that the least power (10,336 kWh) is consumed when the cooling tower’s outlet temperature is 32°C and the generator’s inlet hot water temperature is 105°C.     

Impact of renewable energy on rural electrification in Malaysia: a review

Malaysia is rich in renewable energy (RE) resources. Hybrid systems of these resources can contribute strongly to the electrification and sustainable development of rural areas that do not have access to electricity grids. The integration of the generation of hybrid renewable power in remote and rural areas supplies the required power demand and mitigates emissions. Thus, this study reviews the latest literature (theses, journals articles, and conference proceedings) on the need for electricity in remote rural communities, on hybrid RE systems, on environmental impact, and on economic regulation in Malaysia. Power in this country is mainly generated by fossil fuels that emit high concentrations of greenhouse gases. Thus, RE is a potential alternative for to electrify rural areas, to meet current and future energy demands, and to mitigate emissions. Moreover, Malaysia has pledged to reduce its carbon-emission intensity by a maximum of 40 % (2005 level) by the year 2020. Therefore, the implementation of RE technologies in this country is significantly aided by RE projects, research and development activities, technologies, energy policies, and future direction. This review concludes that solar, wind, hydro, and biomass energy, as well as a hybrid of these, can effectively electrify rural areas.     

Solid biofuels in Mexico: a sustainable alternative to satisfy the increasing demand for heat and power

Bioenergy is the largest renewable energy source in Mexico with an estimated 4–9% of total current energy demand. There are large uncertainties and contrasting estimates regarding its current extent and end-uses, particularly with traditional uses. However, a large potential exists to improve the efficiency of existing uses and, at the same time, to diversify the use of SBF in the industrial and power sectors. This paper aims at: providing the first updated and comprehensive estimate of current SBF demand in Mexico including traditional and modern uses; providing a consistent estimate of actual SBF supply potential; estimating the total potential substitution of fossil fuels that could be achieved by SBF considering an integrated “modernization scenario”; and finally describing the main barriers limiting SBF to fully triggering its potential. Results show that current SBF consumption reached 481 PJ/yr in 2015; SBF supply potential reaches 3622 PJ/yr, out of which 883 PJ/yr could be used to substitute up to 29% of current demand of FF, mitigating 66 MtCO_2e/yr of greenhouse gas (GHG) emissions, or near 88 MtCO_2e/yr if mitigation from traditional uses is added.     

Promotion of wind energy in isolated energy systems: the case of the Orites wind farm

With the establishment of the first wind farm on the island, Cyprus has made progress to satisfy the European Union’s 2020 renewable energy targets. Operational since September 2010, the 174 M€ Orites wind farm is currently the largest wind project in the Mediterranean region. In this article, the main characteristics of the project with regard to Cyprus’s national action plan for the promotion of renewable energy sources are presented. The socio-economic impacts of the project and its feasibility in the context of an isolated energy system are also examined. The results of a public survey to identify the attitudes of surrounding households and neighbouring cities towards the wind farm are presented. The assessment was based on face-to-face interviews conducted with 50 households from the surrounding communities and 100 interviewees from neighbouring cities. According to the survey, the public opinion on the wind farm was generally positive, and the majority of the respondents considered the wind farm to be acceptable as of no considerable environmental impact.     

Evaluation of the energy saving opportunities for palm oil refining process: Sahabat Oil Products (SOP) in Lahad Datu,Malaysia

Palm Oil industry is one of the major contributors to Malaysia’s economic activity. Accounting for 39 % of the world palm oil production and 44 % of world exports, Malaysia holds an important niche in fulfiling the growing global needs for oils and fats sustainably. This industry has high potential for further improvements especially in terms of energy saving as a major contributor to cost and emission reduction. An analysis of the refining process of palm oil in Sahabat Oil Products, Lahad Datu has been performed and presented in this paper for scoping potential energy and cost savings using heat integration. A first stage optimisation of the minimum temperature difference, ?T _min, of a heat exchanger network (HEN) has been performed. The goal has been to evaluate the maximal possible heat recovery as well as the appropriate placement of utilities. The HEN design is presented in both grid diagram and shifted retrofit thermodynamic grid diagram (SRTGD). SRTGD representation has been illustrated in this paper as a useful tool for guiding eventual future retrofit. The capital-energy trade-off of the heat recovery targets indicates optimum ?T _min of 12.3 °C. The hot and cold utility targets at ?T _min = 12.3 °C are 1419 and 1649 kW, indicating potential saving of 3.5 and 3.1 % as compared to the existing utility consumption and emissions. Future work could proceed further to seek potentially viable retrofit of the existing heat recovery network.     

Implementation of ultra high pressure water cutting for treatment of flushed chip seals in the US

This paper discusses implementation of ultra-high pressure (UHP) water cutting as a pavement maintenance strategy based on the first large-scale application of UHP water cutting for treatment of flushed chip seals in the USA. Data are from 13 field sites located in four different climatic regions in Texas. Production rates and treatment costs are sensitive to the UHP water cutter equipment, road surface condition, environmental factors and other variables. Production rates for UHP water cutting under Texas road conditions ranged from 490 m²/h to 1560 m²/h, average 830 m²/h, for treatment of light to heavy flushing. Turn-key unit costs for UHP water cutting varied from US $1.77/m² to US $2.08/m² for an average savings of 41% as compared to the cost of typical Texas maintenance solutions for treatment of flushed chip seals. Overall, UHP water cutting shows positive results in terms of treatment effectiveness, durability and production considerations.     

The dynamic elastic modulus of hardened cement paste. Part I: A new statistical model—water and ice filled pores

The dynamic elastic modulus and damping coefficient of hardened cement paste is measured by exciting the natural mode of oscillation of a hardened cement paste beam in a temperature range between +20 and −160°C. The damping from the system and water vapour exchange with the specimen are negligible. A new statistical model is proposed for combining the elastic moduli of the constituents: solid matrix, water ice and air. Water-saturated specimens were measured, delivering results for the elastic moduli of solid, ice and water by applying the model.     

Production of methanol and organic carbonates for chemical sequestration of CO2 from an NGCC power plant

Global economic development anticipates a growth in demand of the energy sector whose supply in the coming decades will remain achieved by burning fossil fuels. The need to stabilize the CO₂ atmospheric concentration requires technologies for capturing and reutilization of this greenhouse gas. Such scenario motivates feasibility analysis of power generation with post-combustion capture of CO₂ from the flue gas associated with its transformation into chemical commodities. Specifically, the economic performance of an integrated NGCC with post-combustion capture and utilization is evaluated to balance aggregated revenues with energy penalty. The proposed CO₂ reutilization is the production of methanol (MeOH), organic carbonates—dimethyl carbonate (DMC) and ethylene carbonate (EC), and ethylene glycol (EG). The study uses CO₂ capture with MEA (monoethanolamine), including compression of the captured gas followed by its conversion to methanol and organic carbonates, and separation of products with recycle of reactants. Three scenarios were evaluated corresponding to the capture of 30, 50, and 80 % of the CO₂ present in the flue gas. The comparative analysis includes definition of design premises followed by synthesis of process flowsheet, process simulation in the three scenarios, with sizing of the main pieces of process equipments for economic analysis—capital and operational expenditures (CAPEX and OPEX). Results indicated economic feasibility for the three scenarios. Furthermore, energy and mass balances showed that the emissions from energy demand to drive reactions and separations surpasses the proposed sequestration of CO₂ by chemical utilization in the scenarios of 30 and 50 % of CO₂ capture from NGCC emissions. In reality, CO₂ accounting for cases 1 and 2 reveals a “carbon debt” while for case 3 a net positive abatement of CO₂ occurs which increases process revenue by 1.7 % and reduces ROI in 1 year.     

ASRWM: an arid/semiarid region water management model

Water shortage resulting from both natural conditions and human activities has been proved to be a bottleneck that chokes development in arid and semiarid regions. Systems analysis provides an effective way of clarifying conflicts between water supply and demand. In this study, an arid/semiarid region water management (ASRWM) model is developed for sound planning of a water resources system. The proposed model is founded on interval-fuzzy multiobjective programing (IFMOP) for effectively reflecting complexities of the study system and expediently facilitating solution of the model. Member-ship functions for modeling objectives and constraints are formulated to reflect uncertainties in different system components and their interrelationships. To evaluate the applicability of the proposed model, a case study for the Luopu County in northwestern China has been undertaken. The modeling outputs generated through scenario analyses are based on in-depth examination of several sensitive issues including farming, horticulture, stockbreeding, spring water allocation, pasture expansion, and land exploitation. The obtained results lead to two alternatives that provide an useful basis for formulating desired policies of sustainable development in the region. Through the case study, the proposed model is proved to have reasonable computational requirements and to be applicable to large-scale practical planning problems.     

Quantum, classical, and multi-scale simulation of silica–water interaction: molecules, clusters, and extended systems

Over the past 6 years, we have engaged in a multi-faceted computational investigation of water–silica interactions at the fundamental physical and chemical level. This effort has necessitated development and implementation of simulation methods including high-accuracy quantum mechanical approaches, classical molecular dynamics, finite element techniques, and multi-scale modeling. We have found that water and silica can interact via either hydration or hydroxylation. Depending on physical conditions, the former process can be weak ( < 0.2 eV) or strong (near 1.0 eV). Compared to hydration, the latter process yields much larger energy gains (2–3 eV/water). Some hydroxylated silica systems can accept more water molecules and undergo further hydroxylation. We have also studied the role of external stress, effects of finite silica system size, different numbers of water molecules, and temperature dependences.     

Robust fabrication of fluorine-free superhydrophobic steel mesh for efficient oil/water separation

A facile and environmentally friendly method was reported for the fabrication of superhydrophobic steel mesh by depositing with dual-scale Polystyrene@Silica (PS@SiO₂) particles coated with hexadecyltrimethoxysilane (HDTMS), which provided 3D multi-scale hierarchical rough surface structure with low surface energy to perform the superhydrophobic effect. PS particles of ~1 μm and ~200 nm were first synthesized via dispersion polymerization and emulsion polymerization, respectively. The obtained PS particles were then used as template for the silification using tetraethyl orthosilicate as the precursor. After treated with HDTMS, the PS@SiO₂ particles were deposited on steel mesh forming dual-sized hierarchical structures. The as-prepared film exhibited excellent water repellence with a water contact angle of 161.6° ± 1.1° and water contact angle hysteresis of 3.4°. It also showed efficient and rapid oil/water separation ability and could be repeatedly used for at least 5 times. This facile synthesis strategy for fabricating multifunctional steel mesh provides potential applications in large-scale oil–water separation.     

A simplified time-domain design and implementation of cascaded PI-sliding mode controller for dc–dc converters used in off-grid photovoltaic applications with field test results

A time-domain design methodology for voltage regulation control of dc–dc boost and buck-boost converters based on a multi-loop controller with PI regulator for the outer loop and an inner loop with sliding mode current controller has been developed for renewable energy applications such as photovoltaic (PV)-fed dc–dc converters. This paper proposes a new method for the design of PI regulators in such multi-loop control scheme. The proposed design presents a simple analytical method for selecting controller gains and has been validated by simulation as well as hardware implementation. Also, this paper presents an illustrative example based on the proposed design for the voltage regulation control of PV-fed boost converters for off-grid applications. The simulation results for varying irradiation, temperature and load along with stability analysis have been presented in this paper. The proposed controller is implemented in hardware for a 1.1 kW PV-array-fed boost converter. Performance analysis based on field test results using real-time weather data validates the proposed design. Therefore the proposed controller could be considered as an attractive solution for off-grid renewable energy applications like PV- or fuel-cell-fed dc–dc converter, where the variations are stochastic in nature.     

Assessment of R-438A as a retrofit refrigerant for R-22 in direct expansion water chiller

The present work aims to evaluate the performance characteristics of a vapor compression refrigeration system using R-438A as a retrofit refrigerant for R-22. In order to achieve this objective, a test facility is developed and experiments are performed over a wide range of chilled water inlet temperature (11:20 °C), condenser water inlet temperature (25:35 °C) and condenser water mass flow rate (363:543 kg h⁻¹). Results showed that as the chilled water inlet temperature changes from 11.5 to 20.5 °C, system COP increases from 1.78 to 2.07 at constant condenser water inlet temperature of 25.5 °C. Cooling capacity and COP of the system using R-438A are lower than R-22 by 11% and 12.5%, respectively. However, compressor discharge temperature using R-438A is slightly lower than R-22 which confirms that R-438A can be used as a retrofit refrigerant for R-22 to complete the remaining life time of the existing plants.     

Synthesis of platinum single-crystal nanoparticles in water vapor

Platinum (Pt) nanoparticles have broad application in automobile pollution control, sensors, and fuel cells. Single-crystal platinum particles over the range of nano- to micron-meters were synthesized at the Pt/SiC interface in high pressure water vapor at 1200 °C. These particles exhibited a cube–octahedral shape with predominant (111) facets. Formation of the Pt particles is likely due to water vapor-facilitated oxidation of the platinum silicide, resulting from the interaction between SiC and Pt. Well-aligned Pt single-crystal particles with sizes of tens to hundreds nanometers were obtained on the surface of arc-melted Pt₂Si after exposure in flowing water vapor (90 cm/min) at 1200 °C for 5 min. The potential applications of this finding are discussed.     

Tackling the water-energy nexus: an assessment of membrane distillation driven by salt-gradient solar ponds

Although the costs of desalination have declined, traditional desalination systems still need large amounts of energy. Recent advances in direct contact membrane distillation can take advantage of low-quality renewable heat to desalinate brackish water, seawater, or wastewater. In this work, the performance of a direct contact membrane distillation (DCMD) system driven by salt-gradient solar ponds was investigated. A mathematical model that couples both systems was constructed and validated with experimental data available in the scientific literature. Using the validated model, the performance of this coupled system in different geographical locations and under different operational conditions was studied. Our results show that even when this coupled system can be used to meet the future needs of energy and water use in a sustainable way, it is suitable for locations between 40°N and 40°S that are near the ocean as these zones have enough solar radiation, and availability of excess water and salts to operate the coupled system. The maximum freshwater flow rates that can be obtained are on the order of 3.0 L d^?1 per m² of solar pond (12.1 m³ d^?1 acre^?1), but the expected freshwater production values are more likely to be on the order of 2.5 L d^?1 per m² of solar pond (10.1 m³ d^?1 acre^?1) when the system operates with imperfections. The coupled system has a thermal energy consumption of 880 ± 60 kWh per m³ of distillate, which is in the range of other membrane distillation systems. Different operational conditions were evaluated. The most important operating parameters that influence the freshwater production rates are the partial pressure of air entrapped in the membrane pores and the overall thermal efficiency of the coupled system. This work provides a guide for geographical zone selection and operation of a membrane distillation production system driven by solar ponds that can help mitigate the stress on the water-energy nexus.     

Experimental and analytical investigation of water diffusion process in nano-carbon/alumina/silica filled epoxy nanocomposites

This study discusses the water absorption behavior of three different types of nanocomposites. Silica, carbon and alumina nanoparticles are used as fillers incorporated in epoxy resin with different contents of 0.5, 1.5, and 3 wt%. A new nonlinear least-squares regression approach in conjunction with a gradient optimization was developed using symbolic manipulator MAPLE software to find the best fit. The equilibrium moisture content of the nanocomposites is measured as a function of time and the analytical modelling is successfully conducted. Results indicate that the addition of nanoparticles generally lower moisture content in contrast to neat epoxy. Compositions of 1.5 and 3 wt% alumina as well as silica nanocomposites however show a different behaviour. Diffusion coefficients for different types of nanocomposites were computed using Fickian and Langmuir models of diffusion. The least and highest diffusion coefficients correspond to the addition of silica 0.5 wt% and alumina 3 wt%, respectively.     

Issues of water supply and contemporary urban society: the case of Greater Amman, Jordan

Over the last two decades, Jordan has suffered a chronic water crisis, and is the tenth most water-scarce nation on Earth. Such water stress has been well illustrated in the case of Greater Amman, the capital, which has grown dramatically from a population of around 2000 in the 1920s, to 2.17 million today. One of the distinctive characteristics of the water supply regime of Greater Amman is that since 1987 it has been based on a system of rationing, with households receiving water once a week for various durations. Amman is highly polarized socio-economically, and by means of household surveys, both quantitative and qualitative, conducted in high- and low-income divisions of the city, a detailed empirical evaluation of the storage and use of water, the strategies used by households to manage water and overall satisfaction with water supply issues is provided in this paper, looking specifically at issues of social equity. The analysis demonstrates the social and economic costs of water rationing and consequent management to be high, as well as emphasizing that issues of water quality are of central importance to all consumers regardless of their socio-economic status within the city.