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Abstract This Special Section provides introduction to the 15th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES 2012). In this editorial introduction, the editors are highlighting the individual articles included in this issue and discussing the main points. The main areas of this issue can be summarised as: Process Integration for Energy Saving, Integrating Renewable Energy Sources and Energy Optimisation issues.

Abstract Electrolyte-separator-free fuel cell (EFFC) is a new emerging energy conversion technology. The EFFC consists of a single-component of nanocomposite material which works as a one-layer fuel cell device contrary to the traditional three-layer anode–electrolyte–cathode structure, in which an electrolyte layer plays a critical role. The nanocomposite of a single homogenous layer consists of a mixture of semiconducting and ionic materials that provides the necessary electrochemical reaction sites and charge transport paths for a fuel cell. These can be accomplished through tailoring ionic and electronic (n, p) conductivities and catalyst activities, which enable redox reactions to occur on nano-particles and finally accomplish a fuel cell function.

Abstract Hydrothermal liquefaction (HTL) is a promising technology for converting organic-rich waste biomass such as swine manure (SM) and sewage sludge (SS) into energy-dense bio-crude. Until now, one of the major challenges associated with HTL is the pumpability of high dry-matter containing fibrous feedstocks for continuous processing. In this context, this batch scale study presents a suitable approach for enhancing the pumpability of the fibrous material, specifically SM, by co-processing with SS. Obtained results showed that SM was not pumpable itself due to its fibrous nature, but became pumpable by the addition of SS at overall 25 % dry matter content. It was highlighted that the sample mixture containing ~80 % of the SM was smoothly pumped with 20 % SS. Subsequently, HTL experiments were carried out on samples mixed under the ratios SM:SS (100:0, 0:100, 50:50, 80:20, and 20:80). The highest bio-crude yield (42.38 %) via maximum synergistic effect was obtained from the sample SM/SS (50:50) at ratio 1:1 with the best HHV of 36 MJ/kg. Almost 60–70 % mass of all bio-crudes contained volatiles at 350 °C. ICP-AES measurements revealed that the majority of the inorganic elements were concentrated into the solid phase, while 40–50 % of the potassium and sodium were transferred to the aqueous phase. In conclusion, using SS as a co-substrate with SM not only enhances the pumpability of SM, but its co-liquefaction has demonstrated beneficial synergistic effects on improving the energy recovery of the bio-crude.

M.S.S. Santos is grateful to Portuguese Foundation for Science and Technology (FCT) for her PhD fellow (reference: SFRH/BD/104087/ 2014). Kashif Mushtaq is grateful to MIT Portugal Program for his doctoral grant (PD/BD/128041/2016) under the scope of the FCT. The authors would like to acknowledge to the FCT under the scope of the strategic funding of UID/BIO/04469 unit and COMPETE 2020 (POCI 01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145- FEDER-000004) funded by the European Regional Development Fund (ERDF), under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors also acknowledge the Projects: i) POCI-01-0145- FEDER-006939 (LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy – UID/EQU/00511/2013), funded by the ERDF, through COMPETE2020 – Programa Operacional Competitividade e Internacionalizacao (POCI) and by nationals funds through FCT, ii) by the Project SunStorage - Harvesting and storage of solar energy”, with reference POCI-01-0145-FEDER-016387, funded by ERDF, through COMPETE 2020 –POCI), and by national funds, through FCT; (iii) Project PTDC/EQU-EQU/30510/2017 - POCI-01-0145- FEDER-030510 – Sunflow “Solar energy storage into redox flow batteries” funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalizacao (POCI) and by national funds (PIDDAC) through FCT/MCTES and iV) NORTE-01-0145- FEDER-000005 – LEPABE-2-ECO-INNOVATION, supported by North Portugal Regional Operational Programme (Norte 2020), under the Portugal 2020 Partnership Agreement, through the ERDF. The authors are indebted with all the colleagues who assisted in the laboratory work.

This paper is focused on the design criteria of the power conversion systems operating within ultra-fast charging stations for electric vehicles. The proposed architecture is based on a DC bus, which features the integration of renewable energy sources and buffered storage systems, performing the new concept of smart grid system. Simulations of the power converters and storage systems, working as power devices of recharging station architecture, are implemented in the Matlab-Simulink environment with models of each subcomponent provided by the Sim-Power-System tool. The reported simulations are mainly devoted to verify the design criteria of the architecture scheme and the control strategies of the power fluxes related to power converters. The advantages and convenience in terms of power quality and requirementsfrom the main grid are shown, also during the EV fastcharging operations. Finally, the resulted recharging times are evaluated as comparable to the fuelling times generally taken by traditional oil based vehicles.

Many studies have examined the impact of climatic variability on agricultural productivity, although an understanding of these effects on farmland values and their relationship to farmers’ decisions to adapt and modify their land-use practices remains nascent in developing nations. We estimated the impacts of the deviation in our study year's (2012) temperature and precipitation patterns from medium-term (1980–2011) climatic patterns on farmland values in Pakistan. This was accomplished by employing a modified form of a Ricardian regression model. We also examined farmers’ perceptions of climate change during this period, as well as their perceptions of climate change impacts on farm productivity, in addition to past and anticipated farm adaptation strategies. Our results indicate that positive temperature deviation from the medium-term mean – indicative of climatic change – affects farmland values in Pakistan. Deviation in annual cumulative precipitation conversely appears to have no significant impact. Estimates of the marginal impact of temperature deviation suggested a slight but negative linear relationship with farmland values. The location of farms in areas where farmers can avail financial or extension services conversely had a positive impact on farmland values, as did the availability of irrigation facilities. Our analysis of farmers’ perceptions of climate change and their consequent adaptation behavior indicated a relatively high degree of awareness of climatic variability that influenced a number of proactive and future anticipated farm adaptation strategies. Examples included increased use of irrigation and farm enterprise diversification, as well as land-use change, including shifting from agriculture into alternative land uses. National policy in Pakistan underscores the importance of maintaining a productive rural agricultural sector. Our findings consequently highlight the importance of appropriate adaptation strategies to maintain both farm productivity and farmland values in much of Pakistan. The implications of increased extension and financial services to enhance farmers’ potential for climate change adaptation are discussed.

Climate change, soil degradation, and depletion of natural resources are becoming the most prominent challenges for crop productivity and environmental sustainability in modern agriculture. In the scenario of conventional farming system, limited chances are available to cope with these issues. Relay cropping is a method of multiple cropping where one crop is seeded into standing second crop well before harvesting of second crop. Relay cropping may solve a number of conflicts such as inefficient use of available resources, controversies in sowing time, fertilizer application, and soil degradation. Relay cropping is a complex suite of different resource-efficient technologies, which possesses the capability to improve soil quality, to increase net return, to increase land equivalent ratio, and to control the weeds and pest infestation. The current review emphasized relay cropping as a tool for crop diversification and environmental sustainability with special focus on soil. Briefly, benefits, constraints, and opportunities of relay cropping keeping the goals of higher crop productivity and sustainability have also been discussed in this review. The research and knowledge gap in relay cropping was also highlighted in order to guide the further studies in future.

A novel fuel cell device based on integrating the Schottky junction effect with the electrochemical principle is designed, constructed, and verified through experiments. It is found that the Schott ...