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Artículos en revistas Energy, and particularly electricity, has played and will continue to play a very important role in the development of human society. Electricity, which is the most flexible and manageable energy form, is currently used in a variety of activities and applications. For instance, electricity is used for heating, cooling, lighting, and for operating electronic appliances and electric vehicles. Nowadays, given the rapid development and commercialization of technologies and devices that rely on electricity, electricity demand is increasing faster than overall primary energy supply. Consequently, the design and planning of power systems is becoming a progressively more important issue in order to provide affordable, reliable and sustainable energy in timely fashion, not only in developed countries but particularly in developing economies where electricity demand is increasing even faster. Power systems are networks of electrical devices, such as power plants, transformers, and transmission lines, used to produce, transmit, and supply electricity. The design and planning of such systems require the selection of generation technologies, along with the capacity, location, and timing of generation and transmission capacity expansions to meet electricity demand over a long-term horizon. This manuscript presents a comprehensive optimization framework for the design and planning of interconnected power systems, including the integration of generation and transmission capacity expansion planning. The proposed framework also considers renewable energies, carbon capture and sequestration (CCS) technologies, demand-side management (DSM), as well as reserve and CO2 emission constraints. The novelty of this framework relies on an integrated assessment of the aforementioned features, which can reveal possible interactions and synergies within the power system. Moreover, the capabilities of the proposed framework are demonstrated using a suite of case studies inspired by a real-world power system, including business as usual and CO2 mitigation policy scenarios. These case studies illustrated the adaptability and effectiveness of the framework at dealing with typical situations that can arise in designing and planning power systems. info:eu-repo/semantics/publishedVersion

Abstract The necessity of increasing the methane productivity of manure based biogas plants has triggered the application of anaerobic digestion to the separated solid fraction of manure, with the challenge that its high lignocellulosic fibers content is difficult to digest and thus makes anaerobic digestion process slow and economically unfavourable. In the present study, aqueous ammonia soaking (AAS) was investigated as a pretreatment method to increase methane potential of swine manure fibers. 3 days at 22 °C were the optimal conditions among the ones tested (1, 3, and 5 days at 22 and 55 °C) for increasing the methane potential of manure fibers. AAS pretreatment exhibited a significant effect on methane production rate and potential. It was found that AAS for 3 days at 22 °C resulted at a 30–80% and 178% increase in methane yield from digested and raw manure fibers, respectively. Batch anaerobic digestion of AAS-treated digested manure fibers could stand loadings as high as 100 g TS/l inoculum with no inhibition problems. Enzymatic hydrolysis tests applied to AAS-pretreated fibers resulted to 80% and 65% hydrolysis efficiency of glucan and xylan compared to insignificant numbers for non-pretreated fibers confirming thus that AAS effect on methane yield and production rate is due to the facilitation of hydrolysis step of anaerobic digestion process. This is attributed to AAS directly affecting the disintegration step and thus releasing carbohydrates, which can be further hydrolyzed, from the lignocellulosic matrix.

Abstract An open cooling system based on metal hydrides is a promising new technology to reutilize the compression work in a hydrogen pressure tank by generating heat or cold. Our first of its kind system consists of two alternately operating plate reactors, which are filled with around 1.5 kg of Hydralloy C2 ( T i 0.98 Z r 0.02 V 0.41 F e 0.09 C r 0.05 M n 1.46 ) and coupled to a polymer electrolyte membrane fuel cell. In the present study, an extensive performance investigation for a variation of the main influencing parameters is performed: The electrical fuel cell power and the operating temperatures. Overall, it can be observed that in the entire range of various operating conditions, the fuel cell operation is not affected by the alternately operating H2 desorbing reactors. The variation of the electrical fuel cell power between 1.8 and 7.9 kW results in a maximum average cooling power of 807 W at an electrical power of 7 kW, reaching a specific cooling power of 276 W k g M H - 1 . The systems performance decreases with rising ambient temperatures (varied in the range: 24.3–42.3 °C) and decreasing cooling temperatures (varied in the range: 13–25.4 °C) due to increased thermal losses and reduced half-cycle times. Concluding the parameter variations, optimization recommendations are given and the expected performance for an improved system design is derived.

Optimization of biogas production from olive-mill wastewater (OMW) was attempted by codigesting with diluted poultry-manure (DPM) at mesophilic conditions. A series of laboratory experiments were performed in continuously-operating reactors, fed with mixtures of OMW and DPM at various concentrations. It was concluded that codigestion of OMW with DPM is possible without any dilution of OMW or addition of any chemicals. Biogas production was slightly higher when OMW was added to DPM up to a critical concentration (about 40%, expressed as contribution of OMW to the volatile solids of the mixture), after which production is decreased. The results were further verified by scaling up to a continuously-operating pilot-plant reactor digesting DPM, and confirmed that no negative impact was imposed by adding OMW up to the above critical value.

About 72 million households in rural India do not have access to electricity and rely primarily on traditional biofuels. This research investigates how rural electrification could be achieved in India using different energy sources and what the effects for climate change mitigation could be We use the. Regional Energy Model (REM) to develop scenarios for rural electrification for the period 2005-2030 and to assess the effects on greenhouse gas emissions, primary energy use and costs. We compare the business-as-usual scenario (BAU) with different electrification scenarios based on electricity from renewable energy, diesel and the grid. Our results indicate that diesel systems tend to have the highest CO2 emissions, followed by grid systems. Rural electrification with primarily renewable energy-based end-uses could save up to 99% of total CO2 emissions and 35% of primary energy use in 2030 compared to BAU. Our research indicates that electrification with decentralised diesel systems is likely to be the most expensive option. Rural electrification with renewable energy tends to be the most cost-effective option when end-uses are predominantly based on renewable energy, but turns out to be more costly than grid extensions when electric end-use devices are predominantly used. This research therefore elaborates whether renewable energy is a viable option for rural electrification and climate change mitigation in rural India and gives policy recommendations. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract In the last years, a significant interest in research in stand-alone (SA) and grid-connected (GC) photovoltaic (PV)-wind hybrid renewable energy systems (HRES) is observed for their complementary in the satisfaction of the electrical energy demand in many sectors. However, direct comparisons between the techno-economic performance of two system modes under the same operating conditions are rarely carried out. Additionally, most of the researches are limited to specific weather conditions. This work aims to bridge the lack of this type of investigations providing a worldwide techno-economic mapping and optimization of SA and GC PV-wind HRES to supply the electrical demand of an office building district. For this purpose, energy and economic optimization problems were formulated to find the optimal SA and GC systems worldwide among 343 HRES system power configurations located in 48 different localities, uniformly divided in the sub-group of the Koppen classification. The energy reliability and economic profitability of optimal systems were geographically mapped worldwide. In general, the energy or economic optimizations of SA HRES do not lead to highly profitable systems; instead, feed-in-tariff to sell the energy in excess assures viable GC HRES in many localities. However, economically optimal SA and GC HRES, respectively, do not everywhere comply with the threshold value of 70% of the satisfied energy required by the load and are characterized by a high level of energy exchanged with the grid. The study highlighted that the most suitable climate conditions to install a SA HRES are: (i) Toamasina (Madagascar) from an energy point of view, with 76% of load satisfied and 76% of the energy generated utilized to supply the load; (ii) Cambridge Bay (Canada) from an economic point of view, with 11.1% of the capital cost recovered each year; instead, the most suitable climate conditions to install a GC HRES are: (iii) New Delhi (India) from an energy point of view, with 48% of energy exchanged with the grid per each kWh required by the load; (iv) Lihue (Hawaii, United States) from an economic point of view, with 24.3% of the capital cost recovered each year.

Abstract The problem of energy recovery from the electric arc furnace process of steel industry is addressed. During a tap to tap cycle, a significant part of the energy required for steel production is dissipated by the off-gas. The high variability of temperatures and flows, and the high concentration of dust, which characterize the production process, make the adoption of current energy recovery solutions quite difficult, both from the technological and the economical perspective. A new system is proposed exploiting the characteristics of phase change materials (PCM), in particular aluminum, to reduce the variability of off-gas temperatures and thermal powers, in order to allow an efficient energy recovery. The smoothing device is analyzed by thermo-fluid dynamic simulations in order to optimize its performance. A new boiler configuration equipped with cyclones is proposed to overcome also the problem of high dust content of the off-gas. The high recovery efficiencies, the low investment and operation costs and non-invasive plant modifications induced by the smoothing system, make the proposed PCM-based recovery system a feasible solution to reduce energy supply costs and emissions in the steel industry.

The present work addresses energy consumption in raceway ponds (RWPs). This kind of systems are today the most utilized industrial plant for outdoor algae cultivation. The problem has been addressed combining theoretical correlations and experimental data. Head losses for conventional raceway ponds were evaluated, and the results were compared with data available in literature. Computational fluid dynamics was used to support the theoretical analysis. This study suggested possible improvements to the traditional RWP design: an Innovative Raceway Pond (IRP II) was therefore designed, built and operated in parallel with a reference pilot RWP in a test site. Several modifications to traditional RWP design were implemented in the IRP II: the paddle wheel was substituted by a propeller, the water head was reduced and baffle boards were installed in the curves. To validate the new design, head losses and therefore energy consumption in the different systems were evaluated, during cultivation experiments, with two microalgae strains. The theoretical and experimental study allowed a validated calculation, which showed the importance of concentrated head losses towards distributed ones. The analysis highlighted how these losses weight at different pond scales, suggesting possible improvements of the RWP energy performance - as achieved in the IRP II - through revised design for optimized mixing