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Abstract This study sought to quantify and characterize cassava waste as fuel. The wastes from three cultivars were collected to study and were divided into three distinct parts of the cassava plant: seed stem, thick stalks, and thin stalks. Physical and chemical analyzes were carried out to determine the elemental composition of the waste: volatile matter; fixed carbon; ash; moisture; lignin; cellulose; hemicellulose; ash composition and higher heating value were determined. We conducted a thermogravimetric analysis in oxidizing and inert atmospheres to study the behavior of the waste as fuel. The root productivity obtained ranged from 7.7 to 13.0 t ha−1 yr−1 on a dry basis (db), and the ratio between waste and roots varied from 0.36 to 0.91. The physical and chemical properties of cassava waste are analogous to those of woody biomass regarding the elemental composition, the higher heating value, and thermogravimetric analysis. Ash content varied from 2.5% to 3.5%, reaching around 6.0% in samples unwashed. Approximately 60% of the ashes are alkali oxides, especially P2O5, K2O, and CaO, which have low melting points. The alkali index calculated suggests that there is a strong tendency that the combustion process leads to ash fouling and the formation of ash deposits.

This paper estimates the profit of the joint operation of a wind farm and a li-ion battery energy storage system (BESS) in the Iberian electricity market (MIBEL). The day-ahead and first intraday energy markets, and the tertiary regulation market are considered to optimize the joint operation of both assets. A rolling window combined with a non-linear optimization model are used to design the operation strategy. The BESS lifetime (as a function of the depth of discharge) is considered in the optimization problem, and different BESS capacities and initial state of charge values are tested to determine their approximate optimum values. The model and strategy designed were tested using real data from the MIBEL market and predicted data from Sotavento wind farm. The resulting incomes were compared to the BESS investments costs to determine, for a given capacity, when the project becomes viable.

Abstract High power pseudocapacitors are extremely relevant to answer specific needs in the current energy transition arena and to implement an efficient renewable energy society. However, literature shows that are still open gaps concerning improvement of their energy density at high power, conversion efficiency, cost and cycle life. Electrodes based on active transition metal compounds, and in particular metal sulphides, evidence high potential to meet these objectives. This work discusses the dependence on the synthesis route of the charge storage mechanism of manganese sulphide-based materials and relates the pseudocapacitive response of these electrodes with their polycrystalline nature. Results reveal that a manganese oxy-sulphide mixture can achieve a high specific capacitance of 231 F.g−1 at 0.5 A/g in a 0.65 V active window. These values represent a 31.5 % increase compared to pure rambergite, γ-MnS, and 436 % compared to pure hausmannite Mn3O4 prepared under the same conditions. Moreover, the results show that manganese oxy-sulphide electrodes are characterized by good charge retention (73%), and superior long term capacity retention (above 86%) after 5000 cycles, evidencing potential for high power energy storage applications.

This paper explores how market and regulatory factors affect stakeholders' investments in smart grid projects in Europe. Distribution System Operators (DSOs), universities, and technology manufacturers are leading investors, with a cumulative 2286 M€ financed since 2002. Statistical tests were conducted on these groups' investments in smart grid projects in the EU-28, Norway, and Switzerland from 2008-2015, to evaluate the influence of the following factors on investment: the level of distribution sector concentration, the regulatory mechanism in place, and the existence of innovation stimulus mechanisms. The level of distribution sector concentration did not significantly influence investments by these three groups. Market-minded stakeholders, such as DSOs and technology manufacturers, invested more in countries that employed hybrid, incentive, or innovation-stimulus mechanisms; meanwhile, collaborative knowledge-seeking institutions, such as universities, were not swayed by these factors. Taking these findings into consideration will help policy makers design adequate incentives for stakeholders.

An ethanol-methyl- t-butyl ether (MTBE) fuel blend was used as a substitute for hydrated ethanol to improve the vehicle cold start and drivability characteristics during the warm-up period. The vehicle was tested in a cold box, reaching a lower ambient temperature limit of -6deg;C, which represents the most severe weather condition experienced in Brazil. Different concentrations of MTBE in ethanol were investigated. The results show satisfactory drivability characteristics for the tested conditions, comparable with those found in gasoline-fuelled vehicles, thus overcoming the existing cold start difficulties in production ethanol-fuelled vehicles.

The technological development and the low rate of effective improvement of the energetic efficiency in Brazil demonstrate the necessity of work in the area. The aim of this paper is to explore energy efficiency with emphasis in lighting, though an energy audit, which conducted a comprehensive analysis on two aspects, types lamps and the lighting quality. The work achieved a reduction in lighting consumption of 60%, totaling a saving value of R$ 91.747,93 over the life of the system. The investment was paid over a period of one year and two months, it is show a much higher profit than using the investment capital in another financial market application and its rate of return calculated at 7,66% per month and a Payback estimated return one year and eight months.

Sugarcane biorefineries, despite their contribution to sustainable transportation fuels and mitigation of carbon emissions in the mobility sector, produce a large amount of carbon dioxide in their conversion processes. According to the Paris climate agreement, a carbon neutral energy system has to be launched in the years to come, and in this scenario, greenhouse gases emission free industrial processes and alternative carbon sources will be needed. Therefore, this paper presents the evaluation of carbon mass balance of a typical Brazilian ethanol mill to better understand its potential for energy and carbon yield improvement. Due to the fact that Brazilian sugarcane mills are evolving from first generation to integrated first and second generation plant, four different scenarios were analysed. For a first generation plant without (S-I) and with conversion of straw to electricity (S-II) and for the integrated plant (S-III), results of carbon mass balance showed that the harvested sugarcane carbon was mainly converted into CO2 and in a smaller proportion into ethanol. In the modelled cases S-I to S-III the conversion of sugarcane carbon into CO2 and ethanol ranged from 41% to 53% and 17%-22%, respectively. Because this carbon amount in the CO2 flows provides an interesting platform to both increase the bioenergy produced and the harvested carbon-to-fuels ratio, a fourth scenario (S-IV) that studies the integration of power-to-gas (PtG) technologies into the mill was also considered. PtG can increase the sugarcane fuels energy content from 9.3 kW/ha to 33.6 kW/ha using 1361.3 MWe of electricity, increasing the amount of sugarcane carbon transformed into sugarcane based fuels to 54% and converting CO2 into a high value added product.

The sustainability assessment methodology has to be demonstrated in order to become the tool in the engineering practice. This chapter is devoted to the attempt to evaluate the sustainability of energy systems and show how it can be used in the everyday engineering practice. Obviously, this type of approach has its limitation due to the lack of data for the serious consideration of the system. But it should be anticipated that these excises might serve as guidance for eventual future applications. Also, it should be emphasised that this type of methodology will become an useful tool only if it proves to be justified in the engineering practice.

Abstract The energy consumption of spouted bed is an important issue that has been studied from various aspects. In order to investigate the energy consumption of the equipment, several experiments of drying of sorghum bicolor [Sorghum bicolor (L) Moench] were conducted and the results were evaluated looking for the energy performance of the spouted bed. A methodology that takes into account the mechanical energy necessary to maintain the spout regime on the global energy efficiency was proposed and the performance was determined based on the drying efficiency, energy efficiency, and specific energy consumption with and without the term corresponding to the mechanical contribution. This methodology permits a more rigorous evaluation of the energy performance of drying equipment. The percentage increase of the specific energy consumption due to inclusion of the mechanical energy was greater at higher loads and at lower temperatures, demonstrating that this term represented a significant portion of the energy consumption of the process.