Showing papers in "Clean Technologies and Environmental Policy in 2015"

The pollutant emissions from diesel-engine vehicles and exhaust aftertreatment systems

Abstract: Diesel engines have high efficiency, durability, and reliability together with their low-operating cost. These important features make them the most preferred engines especially for heavy-duty vehicles. The interest in diesel engines has risen substantially day by day. In addition to the widespread use of these engines with many advantages, they play an important role in environmental pollution problems worldwide. Diesel engines are considered as one of the largest contributors to environmental pollution caused by exhaust emissions, and they are responsible for several health problems as well. Many policies have been imposed worldwide in recent years to reduce negative effects of diesel engine emissions on human health and environment. Many researches have been carried out on both diesel exhaust pollutant emissions and aftertreatment emission control technologies. In this paper, the emissions from diesel engines and their control systems are reviewed. The four main pollutant emissions from diesel engines (carbon monoxide-CO, hydrocarbons-HC, particulate matter-PM and nitrogen oxides-NOx) and control systems for these emissions (diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction) are discussed. Each type of emissions and control systems is comprehensively examined. At the same time, the legal restrictions on exhaust-gas emissions around the world and the effects of exhaust-gas emissions on human health and environment are explained in this study.

‘Socializing’ sustainability: a critical review on current development status of social life cycle impact assessment method

Abstract: Social life cycle assessment (S-LCA) is a technique to assess the potential social impacts of a product or service caused by its life cycle. The aim of this paper is to critically review the methodologies applied in S-LCIA and establish its current development status by highlighting areas for improvement. The UNEP/SETAC Guidelines published in 2009 provided general procedures for conducting S-LCA, but lack S-LCIA methods. Many new S-LCIA methods have been proposed but these are inherently different, indicating a scientific and well-accepted S-LCIA method is yet to be developed. Broadly, two types of S-LCIA methods, i.e. performance reference point and impact pathways methods are in use. A direction for future research could be the refinement of the social hotspots database and the social hotspot index calculation method. Moreover, the S-LCIA method could be developed by combining the performance reference point and impact pathways methods.

Environmental sustainability assessment of the management of municipal solid waste incineration residues: a review of the current situation

Abstract: Incineration has become an attractive option for municipal solid waste (MSW) management, due to its several benefits. In fact, it allows volume and mass reduction of waste and energy recovery from MSW combustion. Nevertheless, MSW incineration (MSWI) produces three main types of residues: bottom ash (BA), fly ash (FA) and air pollution control (APC) residues, which require an adequate handling. BA is the most significant by-product from MSWI and is generally considered as non-hazardous waste. Instead, FAs are included as hazardous wastes because are characterised by high content of chlorides, heavy metals and organic compounds. The aim of this paper was to examine the characteristics of MSWI solid residues, the management and reuse of these wastes and their environmental assessment from a life cycle perspective. It was noted that the main components that make up the residues are lead and zinc as well as oxides, mainly CaO, SiO2 and Al2O3. Furthermore, it is necessary to take into account the presence of PCDD/F which characterised FA and APC residues, mainly due to chlorine content. Chemical and physical properties of those residues make possible their reuse as construction material, as adsorbent, as well as in geotechnical and agricultural applications. Nevertheless, several studies have demonstrated that a drawback of the reuse of MSWI residues is the existence of heavy metals in elevated concentrations which may affect the environmental quality. In this regard, many studies were aimed to assess the environmental impact related to the introduction of MSWI residues as secondary material in several fields of application.

Performance and emission of diesel engine fuelled by waste cooking oil methyl ester derived from palm olein using hydrodynamic cavitation

Abstract: The depleting of fossil fuel reserves and increasing environmental concerns have continued to stimulate research into biodiesel as a greener fuel alternative produced from renewable resources. In this study, the performance and emission characteristics of biodiesel blends of 10, 30 and 50 % from waste cooking oil based on hydrodynamic cavitation were compared to diesel fuel, and found to be acceptable according to the EN 14214 and ASTM D 6751 standards. The tests have been performed using an in-line vertical six-cylinder diesel engine at different engine speeds, ranging from 1000 to 2000 rpm under full throttle load. During engine performance tests, biodiesel blends showed higher brake specific fuel consumption (2.1–9.0 %) and exhaust gas temperature (1.0–6.8 %), while lower brake power (1.6–6.7 %), torque (0.6–5.2 %) and brake thermal efficiency (1.9–8.4 %) than diesel fuel. Engine emissions showed higher carbon dioxide (8.7–38.5 %) and nitrogen oxide (4.7–19.0 %) releases, but surprisingly decreased amount of carbon monoxide (3.3–26.3 %) for biodiesel blends compared to diesel fuel. Although higher carbon dioxide amounts were emitted, the use of biodiesel greatly reduced the life cycle circulation of carbon dioxide. Waste cooking methyl ester produced by using hydrodynamic cavitation seems to be relatively easy to scale up to higher production values, is energy efficient, time saving and eco-friendly, which results in biodiesel being a viable fuel for industrial production. The waste cooking oil-based biodiesel can also be used without any engine modifications.

Biodesulfurization: a mini review about the immediate search for the future technology

Abstract: A major concern among the environmental agencies includes the emission of sulfurous gas into the environment. Consequently, the oil agencies are in constant search of alternative processes aiming the reduction of sulfur content in fuels. One of the technologies commonly used is the hydrodesulfurization (HDS), but this is a high-cost process that also requires high temperature and pressure. A complementary alternative to HDS is biodesulfurization (BDS) involving the use of specific microorganisms to the removal of sulfur present in the carbon chain, using the oxidation pathway “4S”, in which there is cleavage of carbon–sulfur bond, and maintaining the calorific value of the organic molecule. The BDS is a low-cost technique when compared with HDS. For this process to occur, activation of specific enzymes is needed, which is controlled by dszABC genes. Therefore, strategies to optimize this process have been of great importance to the oil refineries. For decades, attempts to try to implement BDS in the industry have been made, but difficulties in obtaining satisfactory results led the researchers to seek new knowledge about this bioprocess. The need of more studies concerning implementation on an industrial scale of this process is evident, since this biotechnology is a promising alternative to refineries in the near future.

Energy, economic, and environmental analysis of a flat-plate solar collector operated with SiO2 nanofluid

Abstract: To overcome the environmental impact and declining source of fossil fuels, renewable energy sources need to meet the increasing demand of energy. Solar thermal energy is clean and infinite, suitable to be a good replacement for fossil fuel. However, the current solar technology is still expensive and low in efficiency. One of the effective ways of increasing the efficiency of solar collector is to utilize high thermal conductivity fluid known as nanofluid. This research analyzes the impact on the performance, fluid flow, heat transfer, economic, and environment of a flat-plate solar thermal collector by using silicon dioxide nanofluid as absorbing medium. The analysis is based on different volume flow rates and varying nanoparticles volume fractions. The study has indicated that nanofluids containing small amount of nanoparticles have higher heat transfer coefficient and also higher energy and exergy efficiency than base fluids. The measured viscosity of nanofluids is higher than water but it gives negligible effect on pressure drop and pumping power. Using SiO2 nanofluid in solar collector could also save 280 MJ more embodied energy, offsetting 170 kg less CO2 emissions and having a faster payback period of 0.12 years compared to conventional water-based solar collectors.

Assessing and measuring environmental impact and sustainability

Abstract: ‘‘Sustainability’’ is an issue attracting a lot of attention. Just a quick search on 25 February 2015 in SCOPUS \www. scopus.com[ has shown 96,290 publications containing this word. However, looking for both ‘‘Sustainability’’ and ‘‘Assessment’’ in the title and keywords brought just 1,648 papers and the search for ‘‘Sustainability’’ and ‘‘Measurement’’ revealed even less—105 papers dealing with both issues. It means that just 1.7 % of the papers related to sustainability deal with ‘‘Sustainability and Assessment’’ and only 0.1 % with ‘‘Sustainability and Measurement’’. This has been underlining the importance of the extended effort facilitating works and projects dealing with ‘‘Sustainability’’, but not only, the research results, which combine also ‘‘Sustainability’’ with ‘‘Assessment’’ and especially ‘‘Sustainability’’ with ‘‘Measurement’’ and of crucial importance. Various questions have been coming up in relation to sustainability measurement and assessment:

Performance and emission characteristics of a diesel engine with varying injection pressure and fuelled with raw mahua oil (preheated and blends) and mahua oil methyl ester

Abstract: The present experimental investigation aims to depict the effect of varying injection opening pressure (IOP) using diesel-mahua oil (raw) blends as fuel on the characteristics of a small agricultural engine. The effect of preheated mahua oil and mahua oil methyl ester (MOME) as fuel on engine characteristics has also been investigated. Series of short-term tests were conducted on a single cylinder, 3.7 kW, water cooled, stationary diesel engine and performance and emission characteristics were determined using different diesel-mahua oil blends and also with varying IOP. Optimal IOP as well as blend ratio was determined for maximum efficiency and minimum emission values. Further, a novel pipe in pipe counter flow heat exchanger was designed and fabricated to arrange for preheating the raw mahua oil with exhaust gases of the engine. MOME was also prepared and tested as fuel in engine. Characterisation for major properties of all test fuels was conducted. Performance and emission characteristics of the diesel engine for raw mahua oil blends (unheated) at both rated and optimal IOP were compared with those of diesel, MOME and preheated raw mahua oil. At IOP of 226 bar, maximum brake thermal efficiency was obtained for M10, M20 and M30 blends. Significant reduction in carbon monoxide and hydrocarbon emission were observed. Nitrogen oxides emissions increased marginally. It was also observed that preheated mahua oil as fuel increases efficiency and reduces emissions. The use of M10 even at rated injection pressure and M20 and M30 at 226 bar results in minimum loss of efficiency and generates higher environmental benefits.

How can plants manage polycyclic aromatic hydrocarbons? May these effects represent a useful tool for an effective soil remediation? A review

Abstract: Plants are autotrophic organisms which are able to use sunlight and carbon dioxide as the sources of energy and carbon. Plants’ roots absorb a range of natural and anthropogenic toxic compounds for which they have developed some extraordinary detoxification mechanisms. From this point of view, plants can be seen as natural, solar-powered pump-and-treat systems for cleaning up contaminated soils, leading further to the concept of phytoremediation. The phytoremediation of polycyclic aromatic hydrocarbons (PAHs) refers to the use of plants and associated soil microorganisms in terms of reducing the concentrations or toxic effects of these contaminants in the environment. Although there is little evidence to prove that PAHs from soils are accumulated considerably in plants’ parts, there is a lot of evidence that in soils vegetated with grasses and legumes, a significant dissipation of PAHs occurs. Namely, the primary mechanism controlling this process is the rhizospheric microbial degradation, where soil microbial populations use organic compounds as carbon substrates for its growth. This is usually stimulated by roots exudates. The final result of this process is the breakdown and eventual total mineralization of the contaminants. The main challenge in PAH phytoremediation is to improve the performances of plants and rhizospheric microorganisms requiring thus more basic research and knowledge on natural detoxification mechanisms.

Significance of environmental footprints for evaluating sustainability and security of development

Abstract: This contribution presents the selected categories of environmental footprints related to the planetary boundaries and threats to human security. The analysis covers the footprint family of indicators that usually consists of ecological, carbon or more precisely greenhouse gas and water footprints and also sometimes the energy footprint. The other assessed footprints that are important for ecosystem health in regard to water, health, food, and land and species security are nitrogen, phosphorus, biodiversity and land footprints, which have already transgressed the planetary boundaries and are therefore outside the safe operating space. The importance of the various footprints is discussed and the simultaneous analysis of footprints is emphasised as a major direction of research and practice. The comprehensive set of environmental impacts, e.g. set of presented footprints in this contribution, should be considered and should incorporate the burdening and unburdening concept from the life cycle perspective. Some applications of the presented environmental footprints are offered, and conclusions and remarks provided for future observation.

Modeling and simulation of high pressure water scrubbing technology applied for biogas upgrading

Abstract: Depending on the end of use, the quality of biogas must be upgraded in order to utilize the maximum amount of energy necessary for proper applications. Upgrading biogas refers to the increase of methane concentration in product gas by removal of CO2, which increases its heating power. Several treatment technologies are available for biogas upgrading: high pressure water scrubbing (HPWS), pressure swing adsorption, membrane separation, chemical absorption, and gas permeation. Water absorption based on the physical effect of dissolving gases in liquids (HPWS) is a well-known technology and the most effective upgrading process, since provides a simultaneous removal of CO2 and H2S. This could ensure an increasing methane concentration and energy content per unit volume of biogas. In spite of this, few studies are published on biogas upgrading using pressurized water technology. In order to elucidate the performance of HPWS technology at industrial scale with the possibility of water regeneration and recirculation, effects of different operating parameters on the removal of undesired components from biogas were examined, based on modeling and simulation tools. For simulation, the commercial software tool Aspen Plus was applied. Equilibrium model was applied for simulating the absorption process. The simulation results were validated with experimental data from the literature. The results are summarized in terms of system efficiency, expressed as CH4 enrichment, methane loss, and CO2 removal. Finally, new data which can be further applied for scale-up calculations and techno-economic analysis of the HPWS process are provided.

Degradation of azo dyes by laccase: biological method to reduce pollution load in dye wastewater

Abstract: Laccases are the oldest with low substrate specificity enzymes used for degradation of various compounds, especially, dyes. In the present investigation, the cell-free extract of laccase enzyme is applied to degrade azo dyes used in leather processing. The enzyme degrades the azo dyes rapidly at optimum growth conditions of pH 7.0, temperature 37 °C and incubation duration of 72 h. Better production of the enzyme was achieved with dextrose, yeast extract, acetone, copper sulphate and orange peel. The molecular weight of laccase was found to be 63 kDa. The percentage of degradation is found to be 96.4 % for CI Acid black 210 and 92.2 % for the CI Acid black 234. Ultraviolet–visible spectral analysis indicates the presence of peaks in the visible region confirming the complete degradation of the dye sample. Fourier transform-infrared spectroscopy analysis shows the transformation of N=N into either N2 or NH3 and then into biomass. The mass spectra analysis shows conversion of azo dye to final product through various intermediates with their respective molecular weights. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) analysis reveal the reduction of pollution load more than 92 % in the experimental process while maintaining BOD/COD ratio to about 30 %.

Biogas production from locally available aquatic weeds of Santiniketan through anaerobic digestion

Abstract: The current study focused on anaerobic digestion (AD) of aquatic weeds such as water hyacinth and salvinia available in Santiniketan, West Bengal, India. The physico-chemical analysis indicated that water hyacinth and salvinia had a total carbohydrate content of approximately 40, 32 % and C/N ratio of 29, 23, respectively. The AD of the aquatic weeds was carried out in batch mode at 2:1 inoculum to feedstock ratio over a period of 60 days using cow dung as an inoculum. The yield of biogas produced from water hyacinth and salvinia were 552 L kg−1 volatile solids (VS) and 221 L kg−1 VS, respectively. The maximum methane content obtained in the current study was 62 and 63 % for water hyacinth and salvinia. In Salvinia, a maximum volatile fatty acid (VFA) accumulation of 600 mg L−1 was obtained after 16 days of AD and was further reduced to 25 mg L−1 whereas in water hyacinth, little amount of VFA accumulation was observed throughout the digestion period. The chemical oxygen demand was reduced by 66 and 71 % while the VS content was reduced by 27 and 33 % respectively for water hyacinth and salvinia, after 60 days of digestion period. The electricity generation potential from the produced biogas was estimated to be 1.18 kWh for water hyacinth and 0.48 kWh for salvinia.

Heavy metals removal from aqueous solutions by Al2O3 nanoparticles modified with natural and chemical modifiers

Abstract: We prepared novel Al2O3 nanoparticles (NPs) modified with humic acid (Al-H), extractant of walnut shell (Al-W), and 1,5-diphenyl Carbazon (Al-C). The present study was conducted to evaluate the feasibility of modified nano-alumina (Al-H, Al-W, and Al-C) for Cd2+, Cu2+, and Ni2+ removal from single and competitive aqueous solutions. The nature and morphology of sorbents were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and Scanning electron microscopy (SEM) analysis. The SEM results revealed that the three modified nanoparticles had larger size in comparison with bare nanoparticles and with an average diameter of around 61 nm. Batch adsorption studies were performed as a function of contact time, initial heavy metals concentration (isotherm), and pH. Heavy metals sorption kinetics was well fitted by pseudo-second-order kinetic model. The maximum uptake values (sum of 3 metals) in competitive component solutions were 92.0, 97.0, and 63.8 mg g−1, for Al-H, Al-W, and Al-C, respectively. The heavy metals sorption has been well explained using Langmuir isotherm model. SEM–EDX before and after metal sorption, and soil solution saturation indices showed that the main mechanism of sorption for Cd2+ and Ni2+ was adsorption, whereas for Cu2+ sorption was due to adsorption and precipitation. Thus, the new nanoparticles are favorable and useful for the removal of Cd2+, Cu2+ metal ions particularly, in single solutions and with Al-C NPs. The high adsorption capacity makes them good promising candidate materials for heavy metal ions removal from water samples.

Removal of heavy metals and antibiotics from treated sewage effluent by bacteria

Abstract: The increased loads of antibiotics and heavy metals in sewage lead to bacterial cells acquiring resistance to both heavy metals and antibiotics. Therefore, these bacteria can play an important role for removal of pollutants from sewage. The utilization of the microbial processes such as biosorption and enzymatic biodegradation processes has increased during the recent years. These processes are significantly inexpensive and eco-friendly. Enzymatic techniques known as white biotechnology have the ability to degrade complex compounds. Hence, these can be applied to industrial processes. In the current review, the removal of heavy metals and antibiotics from treated sewage effluents by heavy metal/antibiotic-resistant bacteria will be discussed.

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

Abstract: 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.

Removal of lead (II) and nickel (II) ions from aqueous solution using activated carbon prepared from rapeseed oil cake by Na2CO3 activation

Abstract: In this study, rapeseed oil cake as a precursor was used to prepare activated carbons by chemical activation with sodium carbonate (Na2CO3) at 600 and 800 °C. The activated carbon with the highest surface area of 850 m2 g−1 was produced at 800 °C. The prepared activated carbons were mainly microporous. The activated carbon having the highest surface area was used as an adsorbent for the removal of lead (II) and nickel (II) ions from aqueous solutions. The effects of pH, contact time, and initial ion concentration on the adsorption capacity of the activated carbon were investigated. The kinetic data of adsorption process were studied using pseudo-first-order, pseudo-second-order kinetic models and intraparticle diffusion model. The experimental data were well adapted to the pseudo-second-order model for both tested ions. The adsorption data for both ions were well correlated with Langmuir isotherm. The maximum monolayer adsorption capacities of the activated carbon for the removal of lead (II) and nickel (II) ions were determined as 129.87 and 133.33 mg g−1, respectively.

Life cycle assessment of the Spanish cement industry: implementation of environmental-friendly solutions

Abstract: This study tries to find out the hotspots of the Spanish cement sector in 2010 by the life cycle assessment (LCA) and evaluates some improvement scenarios where best available technologies and substitution measures are taken into consideration. The document presents an environmental LCA of the cement production using the 2011 International Reference Life Cycle Data System method recommended by the European Commission. Attending to the clinker production by stage, fossil fuel combustion is the most important source in terms of impacts. Besides, limestone’s calcination is crucial attending to the climate change. Electricity consumption is also relevant both in human toxicity with cancer effects and freshwater eutrophication (FE). Accordingly, solutions deployed lead to reductions in different impact categories. Fossil fuel substitution scenario achieves to reduce 33 and 37 % photochemical ozone formation and acidification (A), while material substitution scenario leads to reduce 10–13 % each impact category. On the other hand, fossil fuel substitution scenario entails an increase of 10 % in FE. Considering the ideal case of applying all these improvements together, reductions go from 15 % in FE to 49 % in A, respectively. To face the problems derived from fossil fuel combustion, a fuel shift is needed to reach less contaminant options such as biomass and bio-waste. Material substitution is another good solution for the industry, but it requires a change in the demand and further research to ensure the properties of cement. Authors recommend taking into consideration the collateral increase of the FE due to the phosphates increase coming from the alternative fuels combustion.

Review of current technologies used in municipal solid waste-to-energy facilities in Canada

Abstract: The increasing amounts of municipal solid waste produced accompanied with the rising need for energy has caused a growth in the popularity of waste-to-energy (WTE) facilities as waste and energy solutions for many regions in Canada. The recent commercially viable WTE facilities across Canada show that the main technologies used in Canada are incineration, gasification, and plasma gasification. The aim of this study is to present these WTE technologies through the examination of case studies taken from the existing facilities across Canada. Background information on case studies, information on the WTE process, and a comparison highlighting the differences between the facilities are discussed.

Artificial neural network model for predicting methane percentage in biogas recovered from a landfill upon injection of liquid organic waste

Abstract: Field-scale investigation for a period of more than four months was conducted to evaluate the performance of a landfill for biogas extraction upon the injection of food waste leachate (FWL), a liquid organic waste generated from the food waste recycling facilities in Korea. The target was set at recovering about 50–60 % methane from the landfill gas (LFG) at extraction rates varying between 10 and 30 m3/h. An application of the artificial neural network (ANN) was presented in this paper to predict the performance parameter namely methane percentage (%). The input parameters to the network were LFG extraction rate (m3/h) and landfill leachate: FWL ratio, respectively, which were obtained from the field-scale investigation. Four different back error propagation learning algorithms were used to train the ANN for a comparative analysis, and the best among them was selected. To substantiate our claim, performance of the network was analyzed for different set of training and test data points. Predictions were attained by appropriately selecting the network parameters and, adequately training the network with 130 set of data points. The accuracy of back propagation neural network (BPNN)-based model predictions was evaluated by calculating the correlation coefficient (R) and mean absolute percentage error values. The results from this predictive modeling work showed that BPNNs were able to predict the methane percentage of the LFG in an acceptable range.

Feasibility analysis of a hybrid off-grid wind–DG-battery energy system for the eco-tourism remote areas

Abstract: The electrification process of the remote areas and decentralized areas is being a vital fact for the improvement of its eco-tourism issues such as the Cameron Highland of Malaysia. Renewable energy (RE) resources can be used extensively to support and fulfill the demand of the expected loads of these areas. This article presents an analysis of a complete off-grid wind-diesel-battery hybrid RE model. The main objective of the present analysis is to visualize the optimum volume of systems capable of ful- filling the requirements of 85 kWh/day primary load in coupled with 8.7 kW peak for 2 residential hotels of Cameron Highlands. The hybrid power system can be effective for the tourists of that area as it is a decentralized region of Malaysia. The main motto of this analysis is to minimize the electricity unit cost and ensure the most reliable and feasible system to fulfill the requirements of the desired or expected energy system using HOMER software. From the simulation result, it can be seen that 15 wind turbines (10 kW), 1 diesel generator (4 kW), and 2 battery (Hoppecke 4 OPzS) hybrid RE system is the most economically feasible and lowest cost of energy is nearing USD 0.199/kWh and net present cost is USD 77, 019. The decrement of the CO2 emissions also can be identified from the simulation results using that most feasible RE system including the renewable fraction value which is about 0.0914, 0.3 % capacity shortage and 20.3 % electricity as storage as compared to the other energy system.

Ionic liquid design for enhanced carbon dioxide capture by computer-aided molecular design approach

Abstract: Carbon capture and storage is an emerging technology to mitigate carbon dioxide (CO2) emissions from industrial sources such as power plants. Post-combustion capture based on aqueous amine scrubbing is one of the most promising technologies for CO2 capture currently. This technology, however, possesses a number of shortcomings, including high regeneration energy requirement, high solvent loss, degradation of solvent, etc. To overcome these limitations, researchers suggested different solvents and alternative technologies to replace the current amine scrubbing technique. Ionic liquids (ILs) are the most potential substitute among all. This is mainly because they have negligible vapour pressure and high thermal stability, which reduce solvent loss. However, there are up to a million possible combinations of cation and anion that may make up the ILs, which makes experimental works very time consuming and costly. In this work, optimal IL solvents specifically for carbon capture purpose are designed using computer-aided molecular design approach. This approach utilises group contribution method to estimate the thermophysical properties of ILs, and UNIFAC model to predict CO2 solubility in the ILs. Structural constraints are included to ensure that the synthesised ILs structure will satisfy the bonding requirement. This work focuses on design of ILs based on a physical absorption mechanism, and hence no chemical reaction is involved. The results show that the designed ILs are capable of capturing CO2 and their predicted properties are in good agreement with properties as determined through experimental works.

Simulation of biomass gasification in downdraft gasifier for different biomass fuels using ASPEN PLUS

Abstract: Biomass utilization through gasification could be a viable alternative energy source for meeting energy demands in decentralized manner Thermodynamic equilibrium and other models have been proposed to explain and understand the complex biomass gasification process, design, simulation, optimization, and process analysis of gasifiers Present paper deals with a comprehensive process model developed for biomass gasification in an atmospheric fixed bed rector using the ASPEN PLUS The experimental facility of the gasifier developed by the authors has a provision for proper cooling and filtration system to derive satisfactory performance with low emissions Thus the model developed using ASPEN PLUS is validated with experimental data obtained with four different types of feed stocks viz; babul wood, neem wood, mango wood, and bagasse The model has well-predicted composition of H2, CO, and CO2 whereas it has under predicted the CH4 The gasifier conversion efficiency was observed to be higher with babul wood when compared with other three types of wood due to its high carbon and H2 and less ash concentrations

Life cycle sustainability assessment (LCSA) for selection of sewer pipe materials

Abstract: Sewer systems, over their life cycle, suffer deterioration due to aging, aggressive environmental factors, increased demand, inadequate design, third party intervention, and improper operation and maintenance activities. As a result, their state and overall long-term performance can be affected, which often requires costly and extensive maintenance, repair, and rehabilitation. Furthermore, these pressures can enhance the risk of failures (e.g., sewer leakage) which in turn can have serious impacts on the environment, public safety and health, economics, and the remaining service life of these assets. Effective asset management plans must be implemented to address long-term sustainability principles, i.e., economic growth, human health and safety, and environmental protection, simultaneously. The aim of this paper is to evaluate and compare four typical sewer pipe materials [i.e., concrete, polyvinyl chloride (PVC), vitrified clay, and ductile iron] and identify sustainable solutions. Two comprehensive life cycle sustainability assessment (LCSA) frameworks were applied. The first LCSA framework was based on the integration of emergy synthesis, life cycle assessment (LCA), and life cycle costing (LCC). In this framework, emergy synthesis has been applied to integrate the results from environmental analysis (i.e., LCA) and economic analysis (i.e., LCC) to an equivalent form of solar energy: a solar emergy joule. The second LCSA framework was based on a conventional, multi-criteria decision-making technique, i.e., the analytical hierarchy process, to integrate the results from environmental analysis (i.e., LCA) and economic analysis (i.e., LCC) and find the most sustainable solution over the sewer pipe life cycle. The results demonstrate that PVC pipe is the most sustainable option from both environmental and economic view points and can ensure a more sustainable sewer system.

Financial analysis for investment and policy decisions in the renewable energy sector

Abstract: The management and exploitation of renewable energy sources is now recognised as central to sustainable development. Environmental concerns, recurring oil crises and market weaknesses, combined with the availability of power from natural resources and resulting possibilities for job creation and energy independence, have all pushed developed and developing countries towards new energy strategies that include RES. This paper analyses the profitability of potential investments in small, medium and large RE electrical power facilities, applying a Net Present Value (NPV) methodology. The proposed financial analysis permits strategic selection of an energy portfolio from among available sources and plant sizes. The paper then discusses potential constraints, and where possible applies the NPV methodology for estimating the necessary changes in decision-making. It defines the role of government incentive schemes in the financial results and evaluates the impact of variation in critical variables (subsidies, sale price of electricity, investment cost, operating cost and equivalent operating hours) on the estimation of NPV. Finally, the paper analyses the environmental impact of all the energy sources examined, examines the links with the financial results and proposes socio-economic policy considerations based on the entirety of the research results. While the methodology is applied to the Italian case, it could be modified to serve in other nations by adapting the input parameters to reflect the different regulatory and market contexts.

Effects of alumina nanoparticles in waste chicken fat biodiesel on the operating characteristics of a compression ignition engine

Abstract: An experimental investigation was carried out to study the performance, emissions and combustion characteristics of a compression ignition (CI) engine fuelled with waste chicken fat biodiesel with alumina nanoparticles as an additive. The disposal of waste chicken creates environmental pollution, hence it is decided to extract oil from the waste chicken fat and produce biodiesel through transesterification process. As the chicken fat contains 13.6 % free fatty acid (FFA), a pre-treatment process was carried out using Ferric sulphate as a catalyst in order to reduce the FFA content less than 1 % to prevent soap formation during the process. Potassium hydroxide was used as catalysts for the effective conversion of triglycerides of waste chicken fat into methyl ester. Various diesel–biodiesel–alumina blends were prepared by varying the biodiesel proportions of 20 and 40 % by volume and 25 and 50 ppm of alumina nanoparticles to study its operating characteristics on a computerized single cylinder, constant speed CI engine. Aluminium oxide (Al2O3) nanoparticles were used as fuel born catalyst in order to enhance the combustion characteristics and reduce the harmful emissions. The engine test results showed less improvement in brake thermal efficiency and significant reduction on the hydrocarbons and carbon monoxide emissions. However, higher nitrogen oxide emissions were recorded due to the increase in combustion temperature as the nanoparticles enhanced the surface area to volume ratio which improves the thermal conductivity of the fuel blend resulted in improved combustion. Smoke reduction of 52.8 % was observed in B40 fuel blend with 50 ppm alumina nanoparticles under full load conditions.

Pyrolysis of agricultural residues for bio-oil production

Abstract: The production of biofuel from biomass waste is of great interest to the scientific community regarding the discovery of solutions to global energy demand and global warming. The pyrolysis of biomass to produce bio-oil is an easy, cheap and promising technology. In the current investigation, the pyrolysis of two different biomasses (cornelian cherry stones and grape seeds) was achieved at temperatures ranging from 300 to 700 °C. The effect of pyrolysis temperatures on the yields of each product was significant. The bio-oil yields were maximized at 500 °C for cornelian cherry stones and 700 °C for grape seeds. The compositions of bio-oils for both cornelian cherry stones and grape seeds were similar and contained mainly oxygenated hydrocarbons. The compounds observed in this investigation were composed of phenols, alkyl benzenes, alkanes, alkenes, fatty acids, fatty acid esters and a few nitrogen-containing compounds. Bio-char properties were amended in association with both the pyrolysis temperature and biomass type. Bio-chars from cornelian cherry stones contained higher carbon and lower oxygen levels than those from grape seeds under identical conditions. Increases in pyrolysis temperatures produced bio-chars containing higher carbon levels and heating values for both carnelian cherry stones and grape seeds.

Processing of residues from biogas plants for energy purposes

Abstract: Maize silage (Atletico, FAO 280) is being anaerobically fermented with cow manure (45 °C, pH 7.1, hydraulic retention time 67 days) in a commercial scale (8,210 MWh electric power and 8,700 MWh heat power per year). The fermentation residues are being mechanically separated into the liquid fraction and the solid pulp (0.9 % hemicelluloses, 8.4 % cellulose, 5.7 % lignin). The solid pulp is being predryed and subsequently pyrolyzed. The pyrolysis takes place in the newly developed horizontal continuous pyrolysis reactor. The technology is run by the hot flue gases (410 ± 11 °C) from the biogas combustion engine (383 m3 of biogas per hour). The carbon powder obtained is being technologically and economically analyzed as a solid biofuel instead of biochar. The results obtained by standardized methods show that the new variety of products obtained outperforms many of the conventional solid biofuels not only in technological and environmental indicators, but also from the economical point of view.

Industrial waste heat recovery and cogeneration involving organic Rankine cycles

Abstract: This paper proposes a systematic approach for energy integration involving waste heat recovery through an organic Rankine cycle (ORC). The proposed approach is based on a two-stage procedure. In the first stage, heating and cooling targets are determined through heat integration. This enables the identification of the excess process heat available for use in the ORC. The optimization of the operating conditions and design of the cogeneration system are carried out in the second stage using genetic algorithms. A modular sequential simulation approach is proposed including several correlations to determine the properties for the streams in the ORC. The proposed approach is applied to a case study which addresses the tradeoffs among the different forms of energy and associated costs. The results show that the optimal selection of the operating conditions and working fluid is very important to reduce the costs associated to the process.

Techno-economic assessment of processing the cellulose casings waste

Abstract: Regarding the developed countries, most of the meat products are packed into cellulose, respectively collagen casings. Minor defects or inaccuracies in threading of the shirred casings on the filling machines result in hundreds of meters of extremely lightweight waste. The logistics of such a waste is costly and other expenses are linked with the ongoing processing of the waste—landfilling. Two other methods of waste management of the cellulose casings (anaerobic fermentation and pyrolysis) were biotechnologically analyzed and financially assessed in a commercial scale. The results obtained confirm that, regardless of the chemical nature, the surface treatment technology of the casings significantly hampers the biodegradability. This makes the fermentation technologies time consuming and therefore economically unworkable. Intensive disintegration techniques are therefore necessary. However, the solid residue of the pyrolysis (also called biochar) represents more attractive product.