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A novel free-standing and flexible counter electrode for dye solar cells has been developed by conveniently transferring a vertically aligned carbon nanotube forest onto an oxygen-plasma-treated flexible, free-standing and conductive nanocomposite foil. Vertically aligned carbon nanotubes were first grown onto an aluminium foil by chemical vapour deposition and then transferred to the nanocomposite surface by hot pressing. The most meaningful electrochemical parameters have been quantitatively analyzed by means of electrochemical impedance spectroscopy and cyclic voltammetry in order to elucidate how the implementation of the anisotropic carbon nanotube top layer impacts the ultimate catalytic performances of the plate. Such an engineered counter electrode is able to guarantee a fast and effective reduction of the iodide-based electrolyte as well as to provide a solar conversion efficiency that is comparable with a typical Pt/TCO-coated rigid counter electrode. A photocurrent density higher than 13.36 mA cm−2 along with a solar conversion efficiency of 7.26% have been reported for the dye solar cell mounting a counter-electrode based on vertically aligned carbon nanotubes implanted onto a conductive nanocomposite plate.

Rapid population growth invokes the need for a vast amount of water conservation. Many centralized water treatment systems will reach their limits and face difficulties to provide clean industrial water to rural areas. The infrastructure for water distribution is dilapidated in many regions and only little of the wastewater is currently being recycled. One solution could be the expansion of decentralized membrane bioreactor (MBR) systems in peri-urban areas. MBR achieves excellent water qualities, whereas the comparatively high energy consumption is the main drawback. Therefore, MBR plants need to be optimized in their specific energy consumption to obtain a high degree of self-sufficiency for decentralized locations. There is a dire need for innovative controlling strategies and efficient coupling with energy supply systems through novel applications. This chapter will highlight the basic approaches to reduce the MBR's overall energy consumption and ways to establish sustainable, autonomous operations without sacrificing the process quality.

The development of a sustainable bio-based economy has drawn much attention in recent years, and research to find smart solutions to the many inherent challenges has intensified. In nature, perhaps the best example of an authentic sustainable system is oxygenic photosynthesis. The biochemistry of this intricate process is empowered by solar radiation influx and performed by hierarchically organized complexes composed by photoreceptors, inorganic catalysts, and enzymes which define specific niches for optimizing light-to-energy conversion. The success of this process relies on its capability to exploit the almost inexhaustible reservoirs of sunlight, water, and carbon dioxide to transform photonic energy into chemical energy such as stored in adenosine triphosphate. Oxygenic photosynthesis is responsible for most of the oxygen, fossil fuels, and biomass on our planet. So, even after a few billion years of evolution, this process unceasingly supports life on earth, and probably soon also in outer-space, and inspires the development of enabling technologies for a sustainable global economy and ecosystem. The following review covers some of the major milestones reached in photosynthesis research, each reflecting lasting routes of innovation in agriculture, environmental protection, and clean energy production.

In the present paper design, realization and testing of a novel small scale adsorption refrigerator prototype based on activated carbon/ethanol working pair is described. Firstly, experimental activity has been carried out for identification of the best performing activated carbon available on the market, through the evaluation of the achievable thermodynamic performance both under air conditioning and refrigeration conditions. Once identified the best performing activated carbon, the design of the adsorber was developed by experimental dynamic performance analysis, carried out by means of the Gravimetric-Large Temperature Jump (G-LTJ) apparatus available at CNR ITAE lab. Finally, the whole 0.5 kW refrigerator prototype was designed and built. First experimental results both under reference air conditioning and refrigeration cycles have been reported, to check the achievable performance. High Specific Cooling Powers (SCPs), 95 W/kg and 50 W/kg, for air conditioning and refrigeration respectively, were obtained, while the COP ranged between 0.09 and 0.11, thus showing an improvement of the current state of the art.

Torrefaction is a relatively new biomass pretreatment technology, which, over the past decades, has been recognized as a very promising and technically feasible method to improve the performance of biomass with regard to storage, handling, transportation and energy conversion processes (Tumuluru et al., 2011; Nhuchhen et al., 2014). Several demonstration plants have seen the light these years, but still a very few commercial plants are currently operating. Despite of the global efforts to develop torrefaction technology, there are still several technical challenges to be addressed in order to realize biomass torrefaction in an economically feasible way at a commercial scale (Chen et al., 2021; Nhuchhen et al., 2014). The major bottlenecks are nowadays the limited control of the process parameters (Brachi et al., 2018; Brachi et al., 2019), in particular the temperature, but the fuel flexibility (size distribution and moisture content) and scale-up of the system are often a barrier as well. In this Research Topic, the editorial team welcomed Original Research dealing with the latest advances in biomass upgrading through torrefaction, from both fundamental and practical points of view. The ultimate objective was to gain deeper insight into the biomass torrefaction to promote its technological development and commercialization. Specific themes covered in this research topic include: 1) the state-of-the-art and perspectives of the torrefaction technology; 2) the optimization of process parameters for a specific feedstock or end-use application (e.g., pyrolysis, adsorption of emerging pollutants, etc.); 3) the design and the process control in torrefaction technologies; and the 4) the chemistry and the reaction kinetics of biomass torrefaction. The articles were contributed by academics and researchers from various institutions in different countries including Canada, China, Belgium, Austria, United States, Taiwan and Brazil.

Latent thermal energy storage systems represent a promising alternative to traditional sensible storages, but their exploitation requires a careful design of the system. The present paper reports a mathematical model for the simulation of thermal energy storage systems with phase change materials (PCMs). The model is suitable for the description of a latent heat storage using a fin-and-tube heat exchanger. Accuracy and computational effort are both taken into consideration, by coupling a 1D model for the tubes of the heat exchanger and a reduced 3D model for the material and fin domains. The developed model has been validated for two systems, realised at ITAE and ISE, differing for the PCM employed and the constructive characteristics of the heat exchanger. Results show that the model has a good accuracy and could predict the behaviour of the storages within 40 W error in case of powers and 1 K in case of heat transfer fluid temperatures. When a stable PCM was used, the average deviation between the PCM temperature in experiments and simulation was lower than 0.6 K.

Global change, in particular climate change, will affect agriculture worldwide in many ways: increased drought or flooding amplitude and frequency, variable temperature increases, loss of natural depuration of waters, soil erosion, loss of soil carbon content, invasion by alien species, increased pest events, changes in plant phenology, increased sensitivity of crops to stress and diseases etc. (Fisher et al. 2005; Howden et al. 2007). These anticipated or even already occurring stresses raise concerns about the sustainability of production and the ability of agriculture to feed human populations. All these changes could lead to an increased use of pesticides (Kattwinkel et al. 2011). Moreover, demographic pressure continues to rise, in particular in tropical and sub-tropical regions, where greater threats to agriculture and food sustainability are anticipated by the Intergovernmental Panel on Climate Change (IPCC) (Easterling et al. 2007). These trends will certainly lead to mounting conflicts involving water uses (irrigation versus drinking water production or freshwater ecosystem maintenance, sanitation etc.) and food production. This appeals to an "ecologically intensive agriculture" (Griffon 2006), i.e. a sustainable agriculture providing ecosystem services more efficiently than today and causing fewer adverse impacts on the environment and water resources. With EU Directive 2009/128/EC (EC 2009a) enforcement, requesting Member States to adopt action plans aiming to reduce risks and impacts related to pesticide uses, there will be a focus in the public and political debates in Europe on achieving a more sustainable use of pesticides. This should consequently lead to a reduction of the risks or impacts of pesticides on the environment. In Europe, there is currently a strong focus on source (including dose) reduction. This approach may nevertheless be too restrictive if the goal is to reduce the agriculture footprint while maintaining or increasing yield. Depending on the chemical properties of pesticides as well as environmental factors, decreasing the amounts of pesticides applied to crops will not automatically produce a decrease in the risk to non-target species or water supply. How could society meet the challenge of the forthcoming climate change? What adaptations should be envisaged for agriculture/pesticide risk management (RM)? These changes will probably have a profound effect on agricultural systems (crop selection, farming practices etc.) and to a lesser extent influence the fate and effects of chemicals (Schiedek et al. 2007). These questions have been addressed by two European research networks, namely Euraqua (the European Network of Freshwater Research Organisations, http://www.euraqua.org/) and PEER (Partnership for European Environmental Research, http://www.peer.eu/), which organised a workshop aiming to identify research needs and strategies induced by these questions in October 2011 in Montpellier, France. The workshop's specific goals were to (1) discuss the pesticide risk assessment (RA) approach, its limitations (e.g.spatial scale and multi-stress situations), the connections between different policies (pesticide regulation and Water Framework Directive), the use of models, (2) review integrated practices and innovative technologies which could or are intended to reduce pesticides' environmental impacts and (3) contribute to the future research and development agenda. This review summarises the workshop discussions.