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In this paper, the performances of two iron-based syngas-fueled chemical looping (SCL) systems for hydrogen (H2) and electricity production, with carbon dioxide (CO2) capture, using different reactor configurations were evaluated and compared. The first investigated system was based on a moving bed reactor configuration (SCL-MB) while the second used a fluidized bed reactor configuration (SCL-FB). Two modes of operation of the SCL systems were considered, namely, the H2 production mode, when H2 was the desired product from the system, and the combustion mode, when only electricity was produced. The SCL systems were modeled and simulated using Aspen Plus software. The results showed that the SCL system based on a moving bed reactor configuration is more efficient than the looping system with a fluidized bed reactor configuration. The H2 production efficiency of the SCL-MB system was 11 % points higher than that achieved in the SCL-FB system (55.1 % compared to 44.0 %). When configured to produce only electricity, the net electrical efficiency of the SCL-MB system was 1.4 % points higher than that of the SCL-FB system (39.9 % compared to 38.5 %). Further, the results showed that the two chemical looping systems could achieve >99 % carbon capture efficiency and emit ~2 kg CO2/MWh, which is significantly lower than the emission rate of conventional coal gasification-based plants for H2 and/or electricity generation with CO2 capture.

Solar Energy Materials and Solar Cells, 116 + (2013) 176-181. doi:10.1016/j.solmat.2013.04.019

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.

With the concept of climate services rapidly climbing research and research-funding agendas worldwide, the time is ripe for a debate about the objectives, scope and content of such services.

The transition to a low carbon future is starting to affect landscapes around the world. In order for this landscape transformation to be sustainable, renewable energy technologies should not cause critical trade-offs between the provision of energy and that of other ecosystem services such as food production. This literature review advances the body of knowledge on sustainable energy transition with special focus on ecosystem services-based approaches and methods. Two key issues emerge from this review: only one sixth of the published applications on the relation between renewable energy and landscape make use of the ecosystem service framework. Secondly, the applications that do address ecosystem services for landscape planning and design lack efficient methods and spatial reference systems that accommodate both cultural and regulating ecosystem services. Future research efforts should be directed to further advancing the spatial reference systems, the use of participatory mapping and landscape visualizations tools for cultural ecosystem services and the elaboration of landscape design principles.

This report aims to provide concept designs to integrate the SunDial/TES system with the MANDREKAS and ArcelorMittal end-users. These concept designs are important to understand how the ASTEP system will be integrated with the end-users including the tailored designs for the specific needs of each end-user. The end-user specific ASTEP system is introduced and existing heating/cooling systems are explained in schematic diagrams. A small number of integration options are presented in detailed schematics. Possible integration components such as steam generator for MANDREKAS and pipe heater for ArcelorMittal are investigated at the component level. In addition, key fluid properties at the critical locations such as inlet and outlet of the components are summarised.

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Hydrogen generation from water using solar energy has grown into a promising approach for sustainable energy production. Over the last years, graphitic carbon nitrides (g-C3N4, CN), polymers based on the heptazine-group, have been widely applied as photocatalysts for H2 evolution. The poor charge separation efficiency of CN is considered the major drawback. Here, we investigated the effect of coupling CN with different types of carbon nanotubes on the charge transfer properties and the photocatalytic H2 evolution. We used carbon nanotubes (CNTs) of different wall number (single (SWCNTs), double (DWCNTs) and multi-walled (MWCNTs) CNTs) for the development of full-organic CN based composite photocatalysts. Photoactivity was drastically affected by the content but more importantly by the nature of the CNTs. The SWCNTs functionalized CN composites were the most active presenting approximately 2-5 times higher H2 evolution than the corresponding DWCNTs and MWCNTs functionalized CN under both solar and pure visible light irradiation. Photoactivity was primarily controlled by the improved electronic properties linked with the abundance and stability of photogenerated charges as evidenced by electron paramagnetic resonance spectroscopy. Transient absorption spectroscopy verified the transfer of reactive electrons from CN to CNTs. CNTs functioned as electron acceptors improving charge separation. The data suggest that charge transfer is inversely proportional to the wall number of the CNTs and that photoactivity is directly controlled by the size at the nanoscale of the CNTs used. In the CNTs/CN nanocomposites, photogenerated electrons are transferred more efficiently from CN when SWCNTs are used, providing more available electrons for H2 production.