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We report the energy performance of a new platinum-free alkaline direct formate fuel cell, equipped with a commercial anion exchange membrane, a nanostructured Pd/C anode and a Fe-Co/C cathode. The cell was investigated both at room temperature and at 60 degrees C for the determination of the following parameters: (i) maximum power density, (ii) delivered energy, (iii) faradic (fuel conversion) and energy efficiency. These parameters show a dramatic dependence on fuel composition. The highest energy efficiency is obtained using high energy density fuel (4 M KCOOH and 4 M KOH) and with a maximum operating temperature of 60 degrees C. This represents a key step in the progress of alkaline platinum-free DFFC technology, demonstrating their potential as power sources for portable electronic devices and remote power generation systems. For example, a fuel load of 750 ml in a DFFC device operating at 60 degrees C would be able to produce 90 W h of energy, that required to fully charge the battery of a laptop computer. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract Alternative fuels are expected to play a major role in EU in the coming years due European Directives on the promotion of renewable energies and reduction of greenhouse gas emissions in transports. However, while in road transports a variety of possible renewable fuels (mainly biofuels, but also electricity) can be considered, in aviation only high quality paraffinic biofuels can be adopted. This means that biomass must be converted through advanced processes into pure hydrocarbon fuels, fully compatible with the existing systems. The aviation sector is responsible for the 2% of the world anthropogenic CO2 emissions and the 10% of the fuel consumption: airlines’ costs for fuel reach 30% of operating costs. In addition, the aviation traffic is expected to double within 15 years from 2012, while fuel consumption and CO2 emissions should double in 25 years. Thus, more than 2 billion people and 40 Mt of good/cargo will have to be moved every year. In this context, the EU Flightpath set a target of 2 Mt per year for aviation alternative fuel by 2020 (i.e. 4% of annual fuel consumption). New processes towards bio-hydrocarbons are being developed, demonstrated and soon industrialized. The present work explores the possible routes from biomass feedstock to sustainable paraffinic fuels, either through bio or thermo-chemical processes, as well as discusses those more mature, focusing on industrial demonstration initiatives. In fact, while the number of possible options towards paraffinic biofuel production is very large, and covers both thermochemical and biochemical routes, as well as hybrid one, only two pathways are today ready for testing a significant large scale: these are FT and Hydrotreating. Major industrial activities and testing experiences are thus reported in the present work. In this context, the ITAKA group is developing a full value-chain in Europe to produce sustainable drop-in Synthetic Paraffinic Kerosene (SPK) – called HEFA – in an economically, socially and environmentally sound manner, at large scale enough to allow testing its use in existing logistic systems and in normal flight operations in Europe. The generated knowledge will aim to identify and address barriers to innovation. Within ITAKA, possible pre-processing of used (waste) cooking oil (UCO) to make it compatible with current downstream hydroprocessing techniques are being investigated: this can includes esterification of waste oils, as well as catalytic thermal processing, which will be carried out in a pilot unit available at RE-CORD/CREAR. First samples of feedstock oils were collected and characterized, for further investigation towards their conversion into biokerosene through hydrotreatment.

Abstract The use of thermal energy storage (TES) systems for solar heating and cooling applications has received considerable attention in recent decades because it has a high potential in energy savings. Phase change materials (PCMs) can store large amount of energy per mass unit compared with other TES materials. Nevertheless, the selection of the suitable PCM for each application is a key issue in any TES system design. The most important properties to take into account to select a PCM are the melting and solidification temperature, the phase change enthalpy and the stability after several thermal cycles. In this paper, d -mannitol was a candidate material to be tested as PCM in a solar cooling application due to its melting point (167 °C) and a relatively high enthalpy (316.0 kJ/kg). The experiments performed by DSC have shown that the d -mannitol presents polymorphic structural changes and, therefore, its thermal properties are not always the same. Depending on the polymorphic phase obtained, d -mannitol has different melting temperature. This behaviour was corroborated in a storage tank, where it may be seen that the cooling rate of the d -mannitol is a key parameter in the formation of the different polymorphic phases.

In this paper we deal with the problem of efficiently optimizing microgrid operations while satisfying a time-varying request and operation constraints. Microgrids are subsystems of the distribution grid comprising sufficient generating resources to operate in isolation from the main grid, in a deliberate and controlled way. The Model Predictive Control (MPC) approach is applied for achieving economic efficiency in microgrid operation management. The method is thus applied to an experimental microgrid located in Athens, Greece: experimental results show the feasibility and the effectiveness of the proposed approach.

Although desalination market is today dominated by Seawater Reverse Osmosis (SWRO), important technological issues remain unaddressed, specifically: relatively low water recovery factor (around 50%) and consequent huge amount of brine discharged, and energy consumption (3-5 kWh/m3) still far from the minimum thermodynamic value (~1 kWh/m3). Herein, the energy performance of an innovative systems combining SWRO, Membrane Distillation (MD) and Reverse Electrodialysis (RED) for simultaneous production of water and energy is investigated. The valorization of hypersaline waste brine by Salinity Gradient Power production via RED and the achievement of high recovery factors (since MD is not limited by osmotic phenomena) represent a step forward to the practical implementation of Zero Liquid Discharge and low-energy desalination. The analysis is supported by lab-scale experimental tests carried out on MD and RED over a broad set of operational conditions. Among the different case studies investigated, exergetic efficiency reached 49% for the best scenario, i.e. MD feed temperature of 60°C, MD brine concentration of 5M NaCl, RED power density of 2.2 W/m2MP (MP: membrane pair). Compared to the benchmark flowsheet (only SWRO), up to 23% reduction in electrical energy consumption and 16.6% decrease in specific energy consumption were achieved when including a RED unit. The analysis also indicates that optimization of thermal energy input at the MD stage is critical, although it can potentially be fulfilled by lowgrade waste heat or solar-thermal renewable sources. Overall, the proposed integrated system is coherent with the emergent paradigm of Circular Economy and the logic of Process Intensification.

The electric engine cooling system, where the coolant pump and the radiator fan are driven by electric motors, admits advanced control methods to decrease auxiliary energy consumption. Recent publications show the fuel saving potential of optimal control strategies for the electric cooling system through offline simulations. These strategies often assume full knowledge of the drive cycle and compute the optimal control sequence by expensive global optimization methods. In reality, the full drive cycle is unknown during driving and global optimization not directly applicable on resource-constrained truck electronic control units. This paper reports state-of-the-art engineering achievements of exploiting vehicular onboard prediction for a limited time horizon and minimizing the auxiliary energy consumption of the electric cooling system through real-time optimization. The prediction and optimization are integrated into a model predictive controller (MPC), which is implemented on a dSPACE MicroAutoBox and tested on a truck on a public road. Systematic simulations show that the new method reduces fuel consumption of a 40-tonne truck by 0.36% and a 60-tonne truck by 0.69% in a real drive cycle compared to a base-line controller. The reductions on auxiliary fuel consumption for the 40-tonne and 60-tonne trucks are about 26% and 38%, respectively. Truck experiments validate the consistency between simulations and experiments and confirm the real-time feasibility of the MPC controller.

Abstract Thermal energy storage systems for both heat and cold are necessary for many industrial processes. High energy density and high power capacity are desirable properties of the storage. The use of latent heat increases the energy density of the storage tank with high temperature control close to the melting point. Tube in PCM tank is a very promising system that provides high packing factor. This work presents an experimental study of a PCM tank for cold storage applications. Two different configurations and different flow rates of the heat transfer fluid were studied. The effectiveness of the PCM storage system was defined as that of a heat exchanger. The results showed that the heat exchange effectiveness of the system did not vary with time, decreased with increasing flow rate and increased with increasing heat transfer area. The effectiveness was experimentally determined to only be a function of the ratio m ˙ /A. This equation was found to be adequately be used to design a PCM storage system, and a case study is presented. It was shown that the tube in tank design together with a low temperature PCM is suitable as a thermal storage facility for cold storage.

Aquifer thermal energy storage (ATES) is a cost-effective technology that enables the reduction of energy use and CO2 emissions associated with the heating and cooling of buildings by storage and recovery of large quantities of thermal energy in the subsurface. Reducing the distance between wells in large-scale application of ATES increases the total amount of energy that can be provided by ATES in a given area. However, due to thermal interference the performance of individual systems can decrease. In this study a novel method is presented that can be used to (a) determine the impact of thermal interference on the economic and environmental performance of ATES and (b) optimize well distances in large-scale applications. The method is demonstrated using the hydrogeological conditions of Amsterdam, Netherlands. Results for this case study show that it is cost-effective to allow a limited amount of thermal interference, such that 30–40% more energy can be provided in a given area compared to the case in which all negative thermal interference is avoided. Sensitivity analysis indicates that optimal well distance is moderately insensitive to changes in hydrogeological and economic conditions. Maximum economic benefit compared to conventional heating and cooling systems on the other hand is sensitive, especially to changes in the gas price and storage temperatures.