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[en] The goal of this work is to provide a multi-method multi-scale comparative picture of selected terrestrial transport modalities. This is achieved by investigating the Italian transportation system by means of four different evaluation methods: material flow accounting (MFA), embodied energy analysis (EEA), exergy analysis (EXA) and emergy synthesis (ES). The case study is the main Italian transportation infrastructure, composed by highways, railways, and high-speed railways (high-speed trains, HST) sub-systems supporting both passengers and freight transport. All the analyses have been performed based on a common database of material, labor, energy and fuel input flows used in the construction, maintenance and yearly use of roads, railways and vehicles. Specific matter and energy intensities of both passenger and freight transportation services were calculated factors affecting results as well as strength and weakness points of each transportation modality were also stressed. Results pointed out that the most important factors in determining the acceptability of a transportation system are not only the specific fuel consumption and the energy and material costs of vehicles, as it is common belief, but also the energy and material costs for infrastructure construction as well as its intensity of use (with special focus on load factor of vehicles). The latter become the dominant factors in HST modality, due to technological and safety reasons that require high energy-cost materials and low intensity of traffic. This translates into very high thermodynamic and environmental costs for passenger and freight transported, among which an embodied energy demand up to 1.44 MJ/p-km and 3.09 MJ/t-km, respectively
[en] The pre-treatment step has a significant influence on the performance of bioenergy chains, especially on logistics. Torrefaction, pelletisation and pyrolysis technologies can convert biomass at modest scales into dense energy carriers that ease transportation and handling. Torrefaction is a very promising technology due to its high process efficiency (94%) compared to pelletisation (84%) and pyrolysis (64%). When torrefaction is combined with pelletisation, the product (TOP) energy content is as high as 20.4-22.7 GJ/ton. The primary energy requirement for TOP delivery from Latin America to Rotterdam harbour can be as low as 0.05 GJ/GJ, in contrast to 0.12 GJ/GJ for pellets and 0.08 GJ/GJHHV for pyrolysis oil. TOP can be delivered to Europe at over 74 Euro /ton (3.3 Euro /GJ) and electricity could be produced as cheap as 4.4 Euro cent/kWhe from an existing co-firing plant. Fisher Tropisch fuel costs 6 Euro /GJHHV for TOP, 7 Euro /GJ for conventional pellets and 9.5 Euro /GJHHV for pyrolysis oil. Consequently, fuel production from TOP and conventional pellets is comparable to the current gasoline production cost ranging from 3 to 7 Euro /GJHHV and diesel from 2 to 7 Euro /GJHHV, depending on the oil market.3 Thus, well designed supply chains make international trade of biomass feasible from energy efficiency and economic perspective
[en] In the presented study, the effects of gasoline fumigation have been investigated experimentally in a single cylinder direct injection (DI) diesel engine. Gasoline has been introduced into the inlet air flow using an elementary carburetor and no other modification on the engine has been done. The effects of 2%, 4%, 6%, 8% and 10% (by vol.) gasoline fumigation have been investigated experimentally at the speeds of (900-1600) (rpm) and at the selected compression ratios of (18-23). From the experimental results it is determined that by application of gasoline fumigation effective power output increases at the levels of 4-9%, effective efficiency increases by approximately 1.5-4% and specific fuel consumption decreases by approximately 1.5-4%. It is also determined that 4-6% fumigation ratio range is the most favorable percentage interval of gasoline at the selected compression ratios for this engine. Because cost of gasoline is higher than diesel fuel in Turkey as well as in many of the other countries and the decrease ratio of specific fuel consumption is low, gasoline fumigation is not economic for this engine. In the presented study, heat balance tests have also been performed for 18 and 21 compression ratios. The heat balance has been investigated experimentally in respect of effective power, heat rejected to the cooling water, heat lost through exhaust, and other losses (unaccounted-for losses). Heat lost through exhaust decreases until 4-6% gasoline fumigation ratios and after these fumigation ratios it starts to increase because of increasing exhaust gas temperature. Heat rejected to the cooling water decreases at low fumigation ratios, but at high fumigation ratios it increases. Other losses generally exhibit an increasing tendency at low fumigation ratios
[en] Fe3O4 supported on cubic yttria-stabilized zirconia (Fe3O4/c-YSZ) is proposed as a promising redox material for the production of hydrogen from water via a thermochemical two-step water-splitting cycle. In this study, the evolution of oxygen and hydrogen during the cyclic reaction was examined using Fe3O4/c-YSZ particles in order to demonstrate reproducible and stoichometric oxygen/hydrogen production through a repeatable two-step reaction. Subsequently, a ceramic foam device coated with Fe3O4 and c-YSZ particles was prepared and examined as a thermochemical water-splitting device in a directly irradiated receiver/reactor hydrogen production system. The Fe3O4/c-YSZ system formed a Fe-containing YSZ (Fe-YSZ) by high-temperature reaction between Fe3O4 and the c-YSZ support at 1400 deg. C in an inert atmosphere. The reaction mechanism of the two-step water-splitting cycle is associated with the redox transition of Fe2+-Fe3+ ions in the c-YSZ lattice. The Fe-YSZ particles exhibit good reproducibility for reaction with a hydrogen/oxygen ratio of approximately 2.0 throughout repeated cycles. The foam device coated with Fe-YSZ particles was also successful for continual hydrogen production through 32 repeated cycles. A 20-27% ferrite conversion was obtained using 10.5 wt% Fe3O4 loading over an irradiation period of 60 min
[en] This paper introduces a mathematical model of a boiler room to research its thermal efficiency. The model is regarded as an open thermodynamic system exchanging mass, energy, and heat with the atmosphere. On those grounds, the energy and energy balance were calculated. Here I show several possibilities concerning how this model may be applied. Test results of the coefficient of thermal efficiency were compared to a real object, i.e. a steam boiler room of the Provincial Hospital in Wloclawek (Poland). The tests were carried out for 18 months. The results obtained in the boiler room were used for verification of the mathematical model
[en] The objective of this article is to analyze the Brazilian Biodiesel Policy (PNPB) and to identify the social and environmental aspects of sustainability that are present or absent within it. Biofuels, namely alcohol and biodiesel, have been increasing in popularity on a global scale due to their potential as alternative and renewable energy sources. Brazil, a vast country blessed with abundant natural resources and agricultural land, has emerged as a global leader in the production of biofuels. This article includes a brief analysis of the concept of sustainable development, which served as a basis to evaluate the Policy documents. Although PNPB's implementation, which began in 2004, is still within its initial stage, it was possible to identify and elaborate on the environmental and social aspects of the Policy, namely: the social inclusion of family farmers; regional development; food security; influencing the carbon and energy balance of biodiesel; promoting sustainable agricultural practices and a diversity of feedstock. (author)
[en] Given recent developments on energy markets and skyrocketing oil prices, we argue for an urgent need to study the potential effects of world oil production reaching a maximum (Peak Oil) in order to facilitate the development of adaptation policies. We consider input-output (IO) modelling as a powerful tool for this purpose. However, the standard Leontief type model implicitly assumes that all necessary inputs to satisfy a given demand can and will be supplied. This is problematic if the availability of certain key inputs becomes restricted and it is therefore only of limited usefulness for the study of the phenomenon of Peak Oil. Hence this paper firstly reviews two alternative modelling tools within the IO framework: supply-driven and mixed models. The former has been severely criticised for its problematic assumption of perfect factor substitution and perfect elasticity of demand as revealed by Oosterhaven [Oosterhaven J. On the plausibility of the supply-driven IO model. J Reg Sci 1988; 28:203-17. ]. The supply-constrained model on the other hand proved well suited to analyse the quantity dimension of Peak Oil and is therefore applied empirically in the second part of the paper, using data for the UK, Japanese and Chilean economy. Results show how differences in net-oil exporting and net-oil importing countries are clearly visible in terms of final demand. Industries, most affected in all countries, include transportation, electricity production and financial and trade services. (author)
[en] The techno-economics of biomass gasification systems for the production of Fischer-Tropsch (FT) based liquid fuels are analysed by estimating the overall mass and energy conversion of biomass to liquid (BTL) fuel. The investigation of BTL systems for 1000 kg/h biomass gasification system and an expected liquid hydrocarbon output of 1500 tonnes are estimated. The cost analysis, based on the annualized life cycle of the systems, includes a steam-oxygen based biomass gasification plant paired with the FT unit. The gasifier considered in this analysis is the downdraft reactor design, operating on oxygen-steam gasifying medium at an equivalence ratio of 0.1 and a steam-to-biomass ratio in the range of 0.8–1.2 to generate syngas with H2/CO ratio of 2.1:1, ideally suitable for the cobalt based fixed bed FT reactor. The mass and energy balance reveal that for a once-through FT reactor configuration, substantial energy exists in the gas phase, which includes C1-C5 hydrocarbons and unconverted syngas. The study suggests that the product gas be utilized in an IC engine and converted to electricity, for in-house power demands and for the sale of excess electricity to the grid. The analysis indicates a market competitive liquid fuel production with CO conversion greater than 60%, at a cost ranging from INR 35–40/litre (0.5–0.6 USD/litre) alongside electricity as a major co-product in the BTL system. This study examines the economics of building economically affordable and environmentally favourable BTL systems of smaller throughputs with particular reference to India. - Highlights: • Investigation on 1000 kg/h, O2-steam biomass gasifier & cobalt catalyzed FT system. • ALC based cost analysis of FT-BTL system to estimate its economic sustainability. • CO conversion should be >60% for market competitive liquid fuel production. • Liquid fuel produced at INR 39.1/l & INR 35.9/l with CO conversion of 65.6% and 73.1%. • Electricity generated as co-product from product gases of once-through FT reactor.
[en] The Korean government has given efforts to reduce green-house gas emissions. In order to avoid the monolithic system that only focuses on reducing the emission without considering operational environments of firms, the government should encourage respective firms to improve their energy efficiency which wastes less energy but produces maximum economic revenue. This paper employed a DEA (Data Envelopment Analysis) model to measure energy efficiency of energy intensive manufacturing firms in Korea. Identifying and comparing the difference in efficiency score by using the simplified single-stage DEA model is not sufficient to give governments and firms meaningful policy implications related to energy efficiency improvement. To compensate for this insufficiency, this study extended the single-stage model into a two-stage model that includes two efficiency measures: pure energy efficiency which is only for energy-related process and economy efficiency which is for the pursuit of profit, to reach the improvement of total energy efficiency. By using the two-stage DEA model, it has identified that the difference from overall energy efficiency is not caused by pure energy efficiency but rather by economy efficiency. In addition, this paper statistically analyzed the effects of environmental variables such as firm size, possession of certified management systems and emission type. - Highlights: • We develop DEA mathematical models for measuring energy efficiency. • The two-stage DEA model includes pure energy efficiency and economy efficiency. • We statistically validates the effects of environmental variables on efficiency. • Overall energy efficiency is more sensitive to pure energy efficiency. • A firm in different conditions has different possibilities to improve its efficiency.
[en] This paper presents an optimal planning and scheduling on energy storage systems (ESSs) for congestion management in electric power systems including renewable energy resources. The proposed problem finds optimal capacity and charging-discharging regime of ESSs. The storage units are optimally charged and discharged to tackle the uncertainty related to wind-solar units as well as relief congestion in the lines. Output power of solar and wind units is modeled by Gaussian probability distribution function (PDF) and Monte-Carlo simulation (MCS) is applied to tackle the uncertainty. Simulation results demonstrate that the proposed planning can manage congestion of the network efficiently while dealing with wind and solar resources uncertainties. - Highlights: • Congestion management is addressed through energy storage planning. • Uncertainty of wind and solar units is considered. • Monte-Carlo simulation is carried out to deal with the uncertainty. • Scenario based stochastic planning is applied to solve the problem. • The planning can tackle the uncertainties and manage congestion of the network.