• Energy Research
• Closed Access close
• 7. Clean energy close
• 13. Climate action close
• IT close
• PL close
• EU close

Biodiesel is a fuel generally consisting of a mixture of fatty acid methyl esters (FAMEs) which is used in alternative or in combination with petroleum diesel for its environmental benefits. Biodiesel is conveniently manufactured from vegetable oils by transesterification of triglycerides with methanol. However, the process brings about the concurrent formation of glycerol, which may become an oversupplied chemical if biodiesel production keeps growing. A novel biodiesel-like material (abbreviated as DMC-BioD) was developed by reacting soybean oil with dimethyl carbonate (DMC), which avoided the co-production of glycerol. The main difference between DMC-BioD and biodiesel produced from vegetable oil and methanol (MeOH-biodiesel) was the presence of fatty acid glycerol carbonate monoesters (FAGCs) in addition to FAMEs. In the following study, details regarding synthesis and composition of DMC-BioD are provided along with physical properties relevant for its use as a fuel. In addition, the production of potential pyrogenic contaminants was investigated by analytical pyrolysis and compared with those from MeOH-biodiesel, and the model compounds tristearin, triolein, trilinolein and oleic acid glycerol carbonate ester (OAGC). The presence of FAGCs influenced both fuel and flow properties, while the distribution of main pyrogenic compounds, including polycyclic aromatic hydrocarbons (PAHs), was little affected. Benefits and drawbacks of DMC as a candidate transmethylating reagent for producing biofuel from renewable resources and alternative co-products (glycerol carbonate and glycerol dicarbonate) are discussed.

Aeroengine manufacturers must continuously develop new high-performance engines, in terms of both specific fuel consumption and pollutant emissions. During the combustion of kerosene, CO 2 and lower amounts of SO 2 , CO, NO x and hydrocarbons are produced; those gases are directly or indirectly responsible for greenhouse effect. Large emission of NO x is produced by engines during the aircraft operation in airport. In the near future, the target in Europe for the aviation sector provides a reduction of SO% of NO x and 50% of CO 2 . For this reason, the hybrid-electric propulsion systems (HEPS) are becoming a viable alternative propulsion technology in the field of aviation, useful to guarantee a massive reduction of pollution. In the paper, the authors analyze and simulate a hybrid turbine/electric engine for a passengers regional aircraft, comparing the results in terms of pollutant and fuel consumption with the conventional thermal engine ones.

It is shown that due to power take-off losses, optimal control provides maximum energy absorption, but not maximum energy production. A new reactive control criterion in the frequency-domain is deduced assuming constant power take-off efficiency, respectively, in the power feeding and power absorption parts of the wave cycle. If applied in the time-domain, this criterion requires the incident wave to be predicted some time into the future. Whilst the OWC type of Wave Energy Converters (WEC) is presented in the paper, the extension to WECs of the floating body type is also considered. Illustrative numerical results for a two-dimensional OWC of simple geometry are presented, which include the performance of this device in three wave spectra with increasing demands of active control for improved energy production. Linear hydrodynamic theory is considered throughout the paper.

Wind turbine gearbox operates under a wide array of highly fluctuating and dynamic load conditions caused by the stochastic nature of wind and operational wind turbine controls. Micropitting damage is one of failure modes commonly observed in wind turbine gearboxes. This article investigates gear micropitting of high-speed stage gears of a wind turbine gearbox operating under nominal and varying load and speed conditions. Based on the ISO standard of gear micropitting (ISO/TR 15144-1:2010) and considering the operating load and speed conditions, a theoretical study is carried out to assess the risk of gear micropitting by determining the contact stress, sliding parameter, local contact temperature and lubricant film thickness along the line of action of gear tooth contact. The non-uniform distributions of temperature and lubricant film thickness over the tooth flank are observed due to the conditions of torque and rotational speed variations and sliding contact along the gear tooth flanks. The lubricant film thickness varies along the tooth flank and is at the lowest when the tip of the driving gear engages with the root of the driven gear. The lubricant film thickness increases with the increase of rotational speed and decreases as torque and sliding increase. It can be concluded that micropitting is most likely to initiate at the addendum of driving gear and the dedendum of driven gear. The lowest film thickness occurs when the torque is high and the rotational speed is at the lowest which may cause direct tooth surface contact. At the low-torque condition, the varying rotational speed condition may cause a considerable variation of lubricant film thickness thus interrupting the lubrication which may result in micropitting.

Recent problems about fossil fuels and environmental pollution carried to an even great interest about alternative energy sources and green-energy. Conversion of biomass in energy through biochemical and thermochemical process is one of the most promising and sustainable solution and, among thermochemical processes, pyrolysis is one of the most investigated. Different setting of parameters allow obtaining various types of pyrolysis processes, resulting in a different distribution in product yield. Before designing the simulation, Authors collected some literature data about existing biomass pyrolysis plant and products obtained through different kind of this process. Layout of simulation is based on a pilot-plant located in Caltagirone (Sicily). The simulation is developed in this paper through CHEMCAD software. The work has two aims: 1. Try to enhance percentage of bio-oil production modifying operative parameter; 2. Give a preliminary parameters and results to improve the process in a real plant. Authors show a synthesis of real pyrolysis plant showing type, steam and dimension of biomass and describing operative parameters as heating rate, residence time and maximum temperature reached during the process. Moreover, there is an overview of the entire production cycle, with a description of equipment such as type of reactor, heat exchangers and equipment of gas washing section, until obtaining of final products. Process is simulated in CHEMCAD through a K-Reactor block able to reproduce the reaction that occurs during pyrolysis. After products are discharged from the reactor, solid particles are collected in a tank whereas gas fraction carry on towards the other section of the plant to be treated. Through gas washing section and cooling process, condensable fraction is obtained and liquid phase is separated from gaseous fraction. To check reliability of results, the percentages of three products are compared with the ones collected through literature researches and there is a matching between them. Proceedings of the 26th European Biomass Conference and Exhibition, 14-17 May 2018, Copenhagen, Denmark, pp. 1131-1136

Abstract Solar radiation can be considered as one of the most suitable energy source to be used for cooking food. It is therefore important to promote advancement in solar cooking systems, in particular as concerns their efficiency and cooking times. In this work, we designed, realized and tested a novel low-cost solar cooker that uses a high-performance light-concentrating Fresnel lens, which is able to concentrate onto a small focal area a large amount of solar radiation. The radiation is then reflected by a mirror towards a cooking surface, where a pot can be located. The cooker has a geometrical concentration ratio of 40.97. In order to characterize the thermal performance of the cooker, we carried out several outdoor tests with a dedicated test setup, using water and silicone oil as absorbing media. Respect to other solar cookers, results show that the proposed cooker is able to reach high temperatures with good efficiency and reduced heating times: 3 kg of water can reach 90 °C in around 30 min, while 3 kg of silicone oil can be taken from 40 to 170 °C in less than one hour.

One of the problems that must be dealt with in a deregulated electricity market is the estimation of the electric power quality of the supply and load. The presence of nonlinear, time-variant, disturbing loads connected to the electric network is responsible for the presence of periodic and nonperiodic disturbances on the line currents and voltages. The availability of indices for the quantification of such disturbances and the assessment of the responsibility for their generation is of utmost importance for the adoption of energy billing policies aimed at discouraging the insertion of uncompensated disturbing loads. This paper analyses a distributed measurement method for the evaluation of a global power quality index for the evaluation of periodic disturbances. The proposed index is validated by means of simulations of the IEEE industrial test system for harmonic modelling and simulation. Some experimental results obtained on a small low-voltage network are also reported.

In Europe, thanks to public subsidy, the production of electricity from anaerobic digestion (AD) of agricultural feedstock has considerably grown and several AD plants were built. When AD plants are concentrated in specific areas (e.g., Northern Italy), increases of feedstock' prices and transport distances can be observed. In this context, as regards low-energy density feedstock, the present research was designed to estimate the influence of the related long-distance transport on the environmental performances of the biogas-to-electricity process. For this purpose the following transport systems were considered: farm trailers and trucks. For small distances (<5 km), the whole plant silage shows the lowest impact; however, when distances increase, silages with higher energy density (even though characterised by lower methane production per hectare) become more environmentally sustainable. The transport by trucks achieves better environmental performances especially for distances greater than 25 km.