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This special issue is dedicated to the research presented and discussed at the 8th International Conference on Sustainable Energy & Environmental Protection held from the 11th to the 14th August 2015 in Paisley, Scotland. The contents of this special issue are within the aims and scope of Renewable and Sustainable Energy Reviews. The aim of the International conferences on Sustainable Energy & Environmental Protection is to gather experts, practitioners and early career researchers together in a relaxed environment to present their research findings. The articles published in this special issue summarise a snapshot of the diverse range of topics from bioenergy and biogas, energy storage and district heating and energy in buildings to carbon emissions, carbon flux in soil and social aspects of carbon discussed at the conference within the framework of sustainable development. A total of eighteen extended manuscripts were invited by for consideration for publication following the conference and after a robust review process by experts in the field a total of ten articles were accepted. [ABSTRACT FROM AUTHOR]

This paper models two strategic decisions made by industrial entities: the intention to adopt a renewable energy system (RES) and the timeframe for this adoption. The methodology presented considers multiple layers of "unobserved heterogeneity." The results of random parameters imply that the parameters exhibit unobserved heterogeneity across industrial entities. For example, high non-electric energy costs increase the probability of selecting a shorter timeframe in 81.8% of entities and reduce that probability in 18.2% of entities. The results of this study also show that the majority (60%) of responding entities intend to adopt an RES within a short timeframe, generally one to two years, while 40% intend to adopt an RES three or more years after 2022. According to our findings, green bank loans, electricity tariffs, the type of industry, government bureaucracy, and entities' export capabilities predominantly influence their intention to adopt an RES. The results also show that energy-intensiveness (e.g., industrial entities in the plastic and rubber, food and drinks, and chemicals and paints sectors), high electricity tariffs, and elevated non-electric energy costs often expedite the adoption process (resulting in shorter adoption timeframes). Government impediments tend to cause entities to delay their adoption decisions. Capital costs are by far the largest impediment to adoption, as indicated by 29.3% of the surveyed entities, followed by government legislation at 18.6%. The findings presented offer crucial knowledge for creating opportunities to implement new policies and produce an environment in which industries can expedite their transitions to renewable energy. • Solar PV demand by the industrial sector is addressed through heterogeneity models. • Two key decisions are addressed: the intention to adopt and the adoption timeframe. • Heterogeneity in means and variances of the random parameters are accounted for. • Several explanatory variables turned out to influence the two demand decisions. • Heterogeneity models are statistically superior to fixed parameters models. [ABSTRACT FROM AUTHOR]

Abstract The world energy consumption is greatly influenced by the aviation industry with a total energy consumption ranging between 2.5% and 5%. Currently, liquid fossil fuel, which releases various types of Greenhouse Gas (GHG) emissions, is the main fuel in the aviation industry. As the aviation industry grows rapidly to meet the requirements of the increased world population, the demand for environmentally friendly power technology for various applications in the aviation sector has been increased sharply in recent years. Among the various clean power sources, energy obtained from hydrogen is considered the future for energy generation in the aviation industry due to its cleanness and abundance. This paper aims to give an overview of the potential aviation applications where hydrogen and fuel cell technology can be used. Also, the major challenges that limit the wide adoption of hydrogen technology in aviation are highlighted and future research prospects are identified. Highlights • The use of hydrogen as a propulsion fuel in the aviation industry is reviewed. • Hydrogen production and storage technologies are explored. • The various aerospace and aviation applications of fuel cell technology are identified. • The major challenges that limit the wide adoption of hydrogen technology in the aviation sector are discussed. [ABSTRACT FROM AUTHOR]

Abstract Carbon capture and storage (CCS) is now known to be an effective way to reduce greenhouse gas emissions especially CO 2 to the atmosphere. Amino acid salt (AAS) solutions are regarded as promising CO 2 absorbents compared to traditional amine solutions, as they are environmentally being with lower evaporation as well as fewer degradation issues. This paper is intended to review recent developments in CO 2 capture using AASs. The thermodynamics and kinetics of CO 2 and different AASs are illustrated in detail. We will also discuss the blended solutions containing AASs in terms of applications and absorption or regeneration performance. Additionally, we will present specific directions for future research on CO 2 -AAS systems. This paper could provide a guideline for effective carbon capture by new absorbents. Highlights • A comprehensive review of amino acid salts fundamentals is introduced. • Detailed thermodynamics and kinetics between CO 2 and various amino acid salts are discussed. • The developments of CO 2 capture by amino acid salts in the fields of biogas upgrading, natural gas and flue gas purification are illustrated. [ABSTRACT FROM AUTHOR]

Fuel cells are among the promising sources of clean energy, considering the low costs, low acoustical pollution, and the high-energy conversion. The remarkable features of graphene and its derivatives have triggered research studies on their applications in PEMFCs. PEMFCs still face some operational challenges for large-scale applications, including high costs, low proton conductivities at high temperatures, mechanical/thermal stabilities, and high fuel crossover. The unique characteristics of graphene-based materials, i.e., high electrochemical stability, good mechanical strength, large surface area, and excellent thermal stability, have been exploited in PEMFCs. This review discusses the potential role of graphene and graphene oxide (GO) in the membranes' structural modifications, and utilization of polymer matrices such as SPEEK, PBI, PANI, SPAES, Nafion, and PVA polymers. The synthesis/functionalization of GO has been investigated with novel composite membranes and mechanisms involved in the enhancements of proton conductions, water uptakes, IECs, and power densities. Graphene materials showed excellent dispersion in solvents and alteration of membrane morphologies. The preceding properties are attributed to the formation of oxygen-based functional groups in GO nano-layers. The incorporation of graphene in other fuel cells, i.e., direct methanol fuel cells and biofuel cells, has exhibited commendable performance and appeared promising for commercial applications, especially with the reduction of fuel crossover. [Display omitted] • Graphene oxide materials in proton exchange membranes are discussed. • Graphene oxide incorporation is achieved due to its compatibility with many solvents. • Graphene oxide modification showed enhanced electrochemical properties in proton exchange membranes. • Reduced fuel crossover was reported in proton exchange graphene oxide-based membranes. [ABSTRACT FROM AUTHOR]

Membrane cost, long-term stability, and sustainability are major concerns when selecting membranes in microbial fuel cells (MFCs) for scaling-up applications. In recent years, efforts have been made to improve reactor architectural designs and to explore ceramic membrane materials, aiming to achieve techno-economical sustainability and efficiency. Furthermore, ceramics have recently emerged as low-cost separators, electrodes, and chassis materials for MFC applications. The introduction of cation exchange minerals into ceramic membranes promotes high proton transfer with improved membrane characteristics. High cationic transfer, proton exchange rate, stability against thermochemical conditions, structural strength to withstand high hydraulic load, and long-term stability with easy biofouling mitigation support the utilization of such membranes for scaling-up use. Successful field trials of Pee-power MFC, stacked urinal MFC, bioelectric toilet, and others showed the feasibility of ceramic membranes for practical applications. Therefore, this review emphasized the membrane characteristics, substantial effect of mineral additives, scaling-up applications, recent developments, and perspectives toward the practical utilization of MFC-based ceramic membranes. [Display omitted] • Ceramic membranes as low-cost alternatives to polymeric membranes in fuel cells. • Ceramics have a wide scope as membranes, electrodes, and chassis for fuel cells. • Long-term stability, high cation exchange rate make ceramics suitable for upscaling. • Cation mineral addition in membranes promotes proton transfer & membrane properties. • Successful scalable trials are positive indicators for fuel cell commercialization. [ABSTRACT FROM AUTHOR]

When two streams of different salinities are mixed, Gibbs free energy of mixing is released. This energy can be harvested and further converted to electric energy through pressure retarded osmosis (PRO) process. Despite several improvements on PRO over the past decades, there still exist several technical issues pertinent to its adequate implementation that remain unresolved. These issues are mainly (i) water transport in the membrane, (ii) membrane material, (iii) fouling, (iv) process efficiency, and (v) techno-economic viability. Different process parameters such as temperature, type of draw solution, feed concentration, and membrane type directly affect the efficiency and power density of PRO. In this review, major trends of PRO (and hybrid plants) are analyzed and the suggested improvements of PRO membranes are discussed. Since potential side-benefits of PRO include electricity production and the treatment of rejected brine from desalination, the process presents a unique path to utilize all these advantages. Therefore, PRO is also coupled with other osmotic, desalination processes to maximize efficiency. The amount of useful energy from PRO would probably be enormous if this was exploited globally. There are several questions remain unanswered about the overall feasibility of PRO as a stand-alone process. This paper offers a comprehensive background and overview on the developments in PRO to enhance its power density and feasibility. • The potential of using PRO for power generation is discussed in this paper. • PRO can be assessed by developing water transfer models and calculating the extractable work. • The recent advances in PRO membranes are reviewed. • The pilot plant studies on hybrid PRO-desalination processes showed enhanced efficiency. • Fouling would probably be the biggest challenge in hybrid-PRO processes. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) is the major contributor to greenhouse gas (GHG) emissions and the main driver of climate change. Currently, CO 2 utilization is increasingly attracting interest in processes like enhanced oil recovery and coal bed methane and it has the potential to be used in hydraulic fracturing processes, among others. In this review, the latest developments in CO 2 capture, utilization, conversion, and sequestration are examined through a multi-scale perspective. The diverse range of CO 2 utilization applications, including mineralization, biological utilization, food and beverages, energy storage media, and chemicals, is comprehensively presented. We also discuss the worldwide research and development of CO 2 utilization projects. Lastly, we examine the key challenges and issues that must be faced for pilot-scale and industrial applications in the future. This study demonstrates that CO 2 utilization can be a driver for the future development of carbon capture and utilization technologies. However, considering the amount of CO 2 produced globally, even if it can be reduced in the near-to mid-term future, carbon capture and storage will remain the primary strategy and, so, complementary strategies are desirable. Currently, the main CO 2 utilization industry is enhanced oil and gas recovery, but considering the carbon life cycle, these processes still add CO 2 to the atmosphere. In order to implement other CO 2 utilization technologies at a large scale, in addition to their current technical feasibility, their economic and societal viability is critical. Therefore, future efforts should be directed toward reduction of energy penalties and costs, and the introduction of policies and regulation encouraging carbon capture, utilization and storage, and increasing the public acceptance of the strategies in a complementary manner. Image 1 • The status of CO 2 utilization via a multi-scale perspective is presented. • Different technologies for CO 2 utilization are discussed and compared. • The worldwide research and development of CO 2 utilization projects is demonstrated. • The key challenges and issues for future applications of Carbon Capture and Utilization are illustrated. [ABSTRACT FROM AUTHOR]