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Searching suitable panchromatic QD sensitizers for expanding the light-harvesting range, accelerating charge separation, and retarding charge recombination is an effective way to improve power conversion efficiency (PCE) of quantum-dot-sensitized solar cells (QDSCs). One possible way to obtain a wide absorption range is to use the exciplex state of a type-II core/shell-structured QDs. In addition, this system could also provide a fast charge separation and low charge-recombination rate. Herein, we report on using a CdTe/CdSe type-II core/shell QD sensitizer with an absorption range extending into the infrared region because of its exciplex state, which is covalently linked to TiO2 mesoporous electrodes by dropping a bifunctional linker molecule mercaptopropionic acid (MPA)-capped QD aqueous solution onto the film electrode. High loading and a uniform distribution of QD sensitizer throughout the film electrode thickness have been confirmed by energy dispersive X-ray (EDX) elemental mapping. The accelerated electron injection and retarded charge-recombination pathway in the built CdTe/CdSe QD cells in comparison with reference CdSe QD-based cells have been confirmed by impedance spectroscopy, fluorescence decay, and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) analysis. With the combination of the high QD loading and intrinsically superior optoelectronic properties of type-II core/shell QD (wide absorption range, fast charge separation, and slow charge recombination), the resulting CdTe/CdSe QD-based regenerative sandwich solar cells exhibit a record PCE of 6.76% (J(sc) = 19.59 mA cm(-2), V(oc) = 0.606 V, and FF = 0.569) with a mask around the active film under a full 1 sun illumination (simulated AM 1.5), which is the highest reported to date for liquid-junction QDSCs.

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.

A water-soluble organic redox couple (TT−/DTT) and new organic dyes (D45 and D51) have been developed for aqueous dye-sensitized solar cells (DSCs). An optimal efficiency of 3.5% was obtained using the D51 dye and an optimized electrolyte composition. The highest IPCE value obtained was 68% at 460 nm.

A commercial drum chipper was fed alternately and piecewise with poplar stems and poplar tops, in order to determine the effect of piece size and tree part on machine performance. Chipping stems required most of the available power (231 kW) delivered by the tractor, whereas chipping tops took about half that much. However, productivity was twice as high with stems, compared to tops (i.e. 25 and 11 t h-1 of oven dry wood, respectively). As a consequence, specific fuel consumption per unit product was 15% lower with stems, compared to tops - i.e. 0.61 and 0.72 L m-3, respectively. Mean feeding speed was 0.37 m s-1 for stems and 0.41 m s-1 for tops, but the difference was not significant (p = 0.1677). Productivity and fuel consumption were strongly related to piece size, but tree part had its own additional effect, independent from size and possibly related to form. When chipping tops it is advisable to feed more pieces at a time, in order to partly compensate for the effect of piece size. Operators expecting to chip primarily small-size materials may acquire special chipper versions with wider drums and additional side rollers, for smoother mass feeding. oThe same chipper was tested with poplar stems and tops.oChipping stems resulted in higher productivity and lower fuel consumption.oChipping stems required most of the available tractor power.oChip particle size distribution was about the same for both feedstocks. © 2013 Elsevier Ltd.

In Italy, olive tree groves may offer up to a million tonnes of dry biomass per year as pruning residue. Searching for a cost-effective way to tap this potential, the authors tested a new machine, capable of recovering pruning residue at the same time as pruning. The pre-commercial prototype was tested on four different plots and compared to a simpler tractorbase mechanical pruning unit. The authors conducted detailed time-studies in order to determine machine productivity and residue recovery cost. The integrated machine can treat between 0.2 and 0.6 ha h(-1), producing between 0.33 and 1.03 tonnes of fresh residue hour(-1). Its integrated residue recovery function does not slow the pruning, which actually proceeds faster than with the tractor-base unit, due to the more efficient multiple-disc cutting bar. The marginal cost of residue recovery hovers around 40-45 (sic) fresh tonne(-1). However, the new machine must not be considered just as a biomass harvester, but rather as a mechanical pruning unit with an integrated biomass recovery function. Its main benefit derives from the capacity of performing a very effective mechanical pruning, and the residue recovery function is a secondary benefit yet unavailable on standard pruning machines. Its deployment must be seen in the context of a general effort to modernize olive grove management and to develop an integrated biomass production system, rather than as a further attempt to build a specialised biomass supply chain.

Electricity generation integrated with xylose degradation was investigated in a two-chamber mediator-less microbial fuel cell (MFC). Voltage output followed saturation kinetics as a function of xylose concentration for concentration below 9.7 mM, with a predicted maximum of 86 mV (6.3 mW m(-2) or 116 mW m(-3)) and half-saturation constant (K(s)) of 0.29 mM. Xylose concentrations from 0.5 mM to 1.5 mM resulted in coulombic efficiencies and maximum voltage ranging from 41+/-1.6% to 36+/-1.2% and 55+/-2.0 mV to 70+/-3.0 mV respectively. Xylose degradation rate increased with increasing xylose concentration up to 9.7 mM and the predicted maximum degradation rate was 0.13 mM h(-1) and K(s) of 3.0 mM. Stirring by nitrogen in the anode chamber led to 99+/-2.3 mV maximum voltage (8.4+/-0.4 mW m(-2) or 153+/-7.1 mW m(-3)) and 5.9+/-0.3% coulombic efficiency at MFC running time 180 h, which were respectively 17+/-1.2% and 37+/-1.8%, higher than those without stirring. The COD removal under stirring was 22.1+/-0.3%, which was slightly lower than that of 23.7+/-0.4% under no stirring. However, stirring resulted in 59% lower xylose degradation rate. This work demonstrates that xylose can be used in the MFC for electricity production. Comparatively higher electricity generation and coulombic efficiency can be obtained by adjusting initial xylose concentration and applying stirring in the anode chamber.

Artículos en revistas Energy transportation costs typically make up a quarter of consumers? electricity bills, and most of this amount (90% in the United Kingdom, 75% in Brazil and Spain, and 60% in India, for example) is due to energy transportation through the distribution network. This cost could escalate over the next few decades as distributed energy resources are expected to grow substantially in response to the financial incentives many governments have created for renewable and efficient generation to meet their CO2 reduction targets. info:eu-repo/semantics/publishedVersion

Abstract In this study, we investigate the driving forces behind the changes in residential energy consumption (REC) in China’s urban and rural areas over the 2001–2012 period. Based on the logarithmic mean Divisia index method, the REC changes are decomposed into seven driving forces, which are climate change, energy price, energy expenditure mix, energy cost share (in total expenditure), expenditure share (in income), per capita income and population effects. According to the results, climate effect due to increasing days with abnormal temperature, energy cost share effect characterized by more expenditure to be paid for energy use, income effect describing constant income growth in the residential sector definitely increase REC in both urban and rural areas. In contrast, energy prices and energy expenditure mix effects negatively contribute to the REC increase, respectively because of the increase in energy prices and the transition from the low-priced energy to high-priced energy. Expenditure share and population effects play opposite roles in urban and rural areas, and the reasons and implications are analysed in depth.