• Energy Research
• Restricted close
• Open Source close
• IT close
• GB close
• CN close
• EU close

In this paper the results from a in-depth life cycle analysis of production and use of a novel grid-connected photovoltaic micromorph system are presented and compared to other thin film and traditional crystalline silicon photovoltaic technologies. Among the new thin film technologies, the micromorph tandem junction appears to be one of the most promising devices from the industrial point of view. The analysis was based on actual production data given to the authors directly from the PRAMAC Swiss Company and it is consistent with the recommendations provided by the ISO norms and updates. The gross energy requirement, green house gas emissions and energy pay-back time have been calculated for the electric energy output virtually generated by the studied system in a lifetime period of 20 years. A comparative framework is also provided, wherein results obtained for the case study are compared with data from literature previously obtained for the best commercially available competing photovoltaic technologies. Results clearly show a significant decrease in gross energy requirement, in green house gas emissions and also a shorter energy pay-back time for the micromorph technology.

Tools and experience on solar thermal cooling system sizing and design are still limited, as less than one thousand plants have been built until now. In this paper, a design tool for mid-size thermal solar cooling systems is presented. The tool consists of a model realised in TRNSYS and validated using the data of a real solar air conditioning system installed in the green building of Shanghai Research Institute of Building Science. Characteristic features of the system are the use of adsorption chillers driven by low-temperature solar heat from U-type and heat pipe evacuated solar collectors. The model has subsequently been employed for a technical analysis: the most relevant parameters have been varied and figures of merit calculated. An energy analysis has been performed for 6 reference cities, differing for climates and latitudes, highlighting the possibility to use only renewable energy for cooling purposes. Eventually, the systems have been compared with reference ones. Comparison highlighted that considerable savings in primary energy and CO2 emissions can be achieved: 0.97 MWh per installed square meter of solar collectors and up to 22 tons of CO2 annually, thus indicating a great potential for increasing energy efficiency and reduce CO2 emissions.

Abstract Methane conversion to a rich H2 fuel by reforming reactions is a largely applied industrial process. Recently, it has been considered for applications combined to gas turbine powerplants, as a mean for (I) chemical recuperation (i.e. chemical looping CRGT) and (II) decarbonising the primary fuel and make the related power cycle a low CO2 releaser. The possibility of enhancing methane conversion by the addition of CO2 to the steam reactant flow (i.e. tri-reforming) has been assessed and showed interesting results. When dealing with gas turbines, the possibility of applying tri-reforming is related to the availability of some CO2 into the fluegas going to the reformer. This happens in semi-closed gas turbine cycles (SCGT), where the fluegas has a typical 14–15% CO2 mass content. The possibility of joining CRGT and SCGT technologies to improve methane reforming and propose an innovative, low CO2 emissions gas turbine cycle was assessed here. One of the key issues of this joining is also the possibility of greatly reduce the external water consumption due to the reforming, as the SCGT is a water producer cycle. The SCGT-TRIREF cycle is an SCGT cycle where fuel tri-reforming is applied. The steam due to the reformer is generated by the vaporization of the condensed water coming out from the fluegas condensing heat exchanger, upstream the main compressor, where the exhausts are cooled down and partially recirculated. The heat due to the steam generation is recuperated from the turbine exhausts cooling. The reforming process is partially sustained by the heat recovered from the turbine exhausts (which generates superheated steam) and partially by the auto thermal reactions of methane with fresh air, coming from the compressor (i.e. partial combustion). The effect of CO2 on methane reforming (tri-reforming effect) increases with decreasing steam/methane ratio: at very low values, around 30% of methane is converted by reactions with CO2. At high values of steam/methane ratio, the steam reforming reactions are dominant and only a marginal fraction of methane is interested to tri-reforming. Under optimised conditions, which can be reached at relatively high pressure ratios (25–30), the power cycle showed a potential efficiency around 46% and specific work at 550 kJ/kg level. When the amine CO2 capture is applied, the specific CO2 emissions range between 45 and 55 g CO 2 / kW h .

The high power density, ease of transportation and storage and many years of development of internal combustion engine technologies have put liquid hydrocarbon fuels at a privileged position in our energy mix. Therefore processes that use renewable energy sources to produce liquid hydrocarbon fuels from H2O and CO2 are of crucial importance. Concentrated Solar Power (CSP) can be employed as the only energy source for the renewable production of hydrogen from water either indirectly, e.g. by supplying the electricity for electrolysis, or directly by supplying the necessary heat for thermochemically producing hydrogen. Among the various thermochemical cycles tested so far for CSP-driven hydrogen production via water splitting (WS), those based on redox-pair oxide systems, are directly adaptable to carbon dioxide splitting (CDS) and/or combined CO2/H2O splitting for the production of CO or syngas, respectively. The acknowledgement of this fact has recently revived the interest of the scientific community on such technologies. The current article presents the development, evolution and current status of CSP-aided syngas production via such redox-pair-based thermochemical cycles. At first the various redox oxide material compositions tested for water/carbon dioxide splitting are presented and their redox chemistries are discussed. Then the selection of suitable solar reactors is addressed in conjunction with the boundary conditions imposed by the redox systems as well as the heat demands, technical peculiarities and requirements of the cycle steps. The various solar reactor concepts proposed and employed for such reactions and their current status of development are presented. Finally, topics where further work is needed for commercialization of the technology are identified and discussed.

AbstractDendronic antennae systems containing pyrene units as energy donors and a styrylpyridinium derivative as energy acceptor show efficient energy transfer from the green‐emitting pyrene excimer to the red‐emitting acceptor. For the third dendron generation the effective screening of the pyrene units on the acceptor provides thin films showing bright red emission. Single‐layer light‐emitting diodes prepared by properly balancing the dendrons and donor units concentration in polyvinylcarbazole show electroluminescence from the blue, green and red components of the monomeric donor, the donor excimer and the acceptor when excitons are generated in the polymer and subsequently transferred to the molecules by resonant energy transfer.

Abstract Dye-sensitized solar cells (DSSCs) with photoanodes composed of chirality selected single-wall carbon nanotubes (SWNTs) have been fabricated and tested for first time. Single chirality SWCNTs separation (93% purity) have been achieved by modifying standard size exclusion gel chromatography. Chirality selection has allowed for “tuning” of the energy barrier at the TiO2/SWNT/FTO interface, electronic conductivity enhancement, and reduced SWCNTs-ruthenium dye competition for light absorption resulting in a 81% energy conversion efficiency improvement compared to mixed chirality cells. Unfortunately, energy conversion efficiency has been limited by cells’ low shunt resistance. Additionally, SWCNTs electron transfer properties have been exploited to prepare mixed and chirality specific CNTs based DSSCs’ counter electrodes.

Environment preservation, energy, and the growing economy are becoming strongly interconnected themes requiring new solutions to be exploited. An example of this interconnection is the demand for the development of almost zero-energy buildings, i.e. buildings capable to be almost autonomous from external energy supply or at least not dependent on the energy supply from utilities. The actual conception of a zero energy building is a very complex system formed by several subsystems, with the consequence that costs are very high and reliability relatively low. The aim of this research program is to deepen the possibility to employ the Stirling engine and cooler technology to lower the number of components required in a near zero-energy building, increase the efficiency, and contemporary raise the reliability of the overall system. Stirling cooler could be used to convert mechanical work into heating and cooling effects and produce the temperature difference by the expanding and compressing the working fluid. A similar concept of the Stirling cooler could also be adopted to develop a heat pump. Compared to the traditional vaporcompression refrigeration systems, the Stirling coolers are of higher efficiency and with no components like compressor, expansion valve, evaporator, or condensers. Therefore, they are considered to be clean cooling devices. On the other hand, the Stirling engine is an external combustion engine, which is compatible with a variety of thermal sources, such as solar radiation, waste heat, geothermal energy, combustion, and so on. With the heat input to the hot end of the engine, the Stirling engine could be operated to produce mechanical work/electricity at high thermal efficiency. In principle, the Stirling machines are capable to provide all the forms of energy (heat, cool, and electricity) that form the almost total energy load of a building.

Starting from an interpretation of “sustainable mobility”, this study describes a possible taxonomy of the modalities of urban travels related to sustainability and it suggests an inclusive approach to implement urban policies for “soft mobility” inside the urban contexts. These policies aim at improving the levels of urban liveability, reducing the polluting emissions and promoting the recovery of a sober moral behaviour in acting and reacting inside the city. The underway photovoltaic bikesharing project “Bene Bike” in Benevento shows how the bike station plays an innovative role. It represents a multifunctional element able of managing material and immaterial “flows of urban travels” (people, energy, information).