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This paper presents the editorial for the Renewable and Sustainable Energy Reviews joint special issue devoted to the research work discussed and presented at the 11th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES), held from the 4th September to the 9th September 2016 in Lisbon, Portugal and the 2nd South East European (SEE) SDEWES Conference held from June 15th to June 18th, 2016 in Piran, Slovenia. This special issue is in line with the journal's aim of publishing research from across the ever-broadening field of renewable and sustainable energy with a strong review element. Previous SDEWES conference special issues have gathered a significant knowledge base in the field of sustainable development that reflects the continuous research efforts of the SDEWES research community. Therefore, this editorial provides not only an overview of the papers published in this particular special issue, but also a wider overview of the current trends in the domain of sustainable and renewable energy. This year's special issue focuses particularly on the benefits of the bio-based economy, energy security issues, fossil fuel thermal plant alternatives and environmental constraints, district heating and cooling together with cross sector energy efficiency and energy conservation issues. Sustainable transport systems, the issue of fuel poverty in urban neighbourhoods and renewable energy to support development of peripheral rural areas, optimising passive building design for hot climates and solar-powered heating and cooling are further topics featured in this special issue. In the process of selecting papers for this special issue, the guest editors invited in total 23 extended manuscripts for consideration for publication. After a rigorous review process by expert reviewers overseen by the guest editors a total of 16 articles were accepted for publication. [ABSTRACT FROM AUTHOR]

This paper reviews methods that measure mineral resource depletion based on cumulative exergy consumption approaches. It focuses on the exergy replacement cost (ERC), which measures the amount of exergy society would have to consume in order to re-concentrate an extracted and processed mineral to the point that it can be once more exploited by future generations. The ERC, which was originally only suitable for non-fuel minerals, was adapted and extended in 2016, by changing the focus of the ERC from the chemical composition of the resource to its function, to include fossil fuel depletion. This paper discusses the impact of these new developments and identifies conceptual and methodological weaknesses that need to be addressed for the ERC to find widespread use in exergy analysis and in order to assess the sustainability of mineral policy from the grave to the cradle. [ABSTRACT FROM AUTHOR]

Biofuel production has stood out at the international level on account of its more environmentally sustainable characteristics and the potential to promote rural development in developing countries. In Brazil, biodiesel is being produced through legislation requiring the addition (currently 7%) of biofuel to petroleum diesel. The federal program (PNPB) aimed the social inclusion of small farmers and diversification of Brazilian matrix by incentives regional crops production. The possibility of broadening raw material sources for biodiesel production benefits the Brazilian competitiveness. At the same time, facing the vast varieties of raw materials available in this country, it is a challenge to figure out which crop would be more appropriate to this chain. The palm species Acrocomia aculeata ( macaúba ) could provide an alternative resource for energy diversification in Brazil and Latin American countries. The crop species has drawn attention due to its high productivity rates and because it is not used for food purposes. In this sense, this paper examines the opportunity of biodiesel production from A. aculeata as a potential source for future energy supply, particularly for biodiesel, especially in Brazil. This paper presents A. aculeata and some points that allow compare with other crops. Several related aspects are covered in this paper, such as economics, botanical description, the extraction and compositions, physical and chemical properties of crude A. aculeata oil and fatty acid composition of A. aculeata . [ABSTRACT FROM AUTHOR]

Climate change is one of the main threats of the modern society. This phenomenon is associated with the increase of the greenhouse gases (GHGs, mainly carbon dioxide – CO 2 ) emissions due to anthropogenic activities. Main causes are the burning of fossil fuels and land use change (deforestation). Climate change impacts are associated with risks to basic needs (health, food security and clean water) as well as risks to development (jobs, economic growth and the cost of living). Taking into account this phenomenon, several countries participated in the last United Nations Climate Change Conference in Paris (21st Conference of the Parties – COP21) and agreed to reduce their GHG emissions to limit the rise in global temperature to less than 2 °C. Main commitments and actions are focused in energy efficiency, renewable energy deployment and forest protection (increasing the CO 2 natural sinks). In this context, biofuels (from non-edible feedstocks) have the potential to replace fossil based fuels in the transport sector, being a carbon-neutral fuel. In particular, algae–based biofuel can play a dual role in this scenario: as photosynthetic organisms, algae can capture CO 2 from industrial emissions or from atmosphere and the resulting biomass can be used to produce a wide range of materials including biofuels. Therefore, this paper reviews the research advances of algae cultures with focus on the applications (CO 2 capture and bioenergy production) related to the targets of COP21 agreement. Main recent advances in algal research studies and projects are also presented. [ABSTRACT FROM AUTHOR]

Uncertainties in evaluating bioenergy projects have lead policymakers to adopt a restrictive approach or even refuse to evaluate projects when the available information is limited or a clear perception of its benefits and impact is lacking. Indeed, despite its potential advantages, a bioenergy system poses several conceptual and operational challenges for academic as well as practical scrutiny because the inherent relationship and the intersection of areas related to energy production and agricultural activity requires a deeply integrated assessment. The aim of this paper is to review the available works in this field and propose an approach for supporting policymakers in the taking decision process of deploying sustainable bioenergy systems. The SIByl-LACAf framework provides a comprehensive framework for addressing the inherent complexity of the subject and its sustainability and acceptability as part of the evaluation process. With this approach, different and complementary evaluation methods are reviewed and set in a logical and sequential structure to draw a group of indicators used for assessing a given project with the help of a strengths, weaknesses, opportunities, and threats (SWOT) matrix. When acceptability is identified as an issue, a Public Consultation and Communication (PC&C) scheme can complement this process. The suggested application for Mozambique indicate that an acceptable outcome is possible even when considering the data requirements and constraints of developing countries. Thus, the potential of this integrated approach outweighs such limitations. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a generic approach for selecting sustainability criteria and indicators (C&I) by using a participatory methodology. Selecting appropriate C&I to assess the sustainability of projects or developments is crucial and significantly influences the assessment results. The methodology, which consists of two processes: a pre-selection of suitable C&I by the researchers and a final selection by regional bioenergy experts in a multi-stakeholder forum, was applied in a Scottish region (Tayside & Fife). The paper concludes that the methodology provides a transferable approach to systematically select C&I and to justify this selection. Furthermore, the pre-selected and final C&I for the case study can serve as a benchmark set and starting point for similar decision making situations in other regions. In order to provide a wide application potential for the bioenergy field, the case study took account of a range of scenarios and alternatives. Moreover, the identified C&I and requirements for selection from literature provide a broad application potential to assist C&I selection, as they cover the sustainability field in general, the energy sector and the bioenergy sector in particular. [Copyright &y& Elsevier]

The increasing production of modern bioenergy carriers and biomaterials intensifies the competition for different applications of biomass. To be able to optimize and develop biomass utilization in a sustainable way, this paper first reviews the status and prospects of biomass value chains for heat, power, fuels and materials, next assesses their current and long-term levelized production costs and avoided emissions, and then compares their greenhouse gas abatement costs. At present, the economically and environmentally preferred options are wood chip and pellet combustion in district heating systems and large-scale cofiring power plants (75–81 US$ 2005 /tCO 2 -eq avoided ), and large-scale fermentation of low-cost Brazilian sugarcane to ethanol (−65 to −53 $/tCO 2 -eq avoided ) or biomaterials (−60 to −50 $/tCO 2 -eq avoided for ethylene and −320 to −228 $/tCO 2 -eq avoided for PLA; negative costs represent cost-effective options). In the longer term, the cultivation and use of lignocellulosic energy crops can play an important role in reducing the costs and improving the emission balance of biomass value chains. Key conversion technologies for lignocellulosic biomass are large-scale gasification (bioenergy and biomaterials) and fermentation (biofuels and biomaterials). However, both routes require improvement of their technological and economic performance. Further improvements can be attained by biorefineries that integrate different conversion technologies to maximize the use of all biomass components. [ABSTRACT FROM AUTHOR]

Abstract: Meeting future policy targets for bioenergy development worldwide poses major challenges for biomass feedstock supply chains in terms of competitiveness, reliability and sustainability. This paper reviews current knowledge on the sustainability of agricultural feedstock supply chains and emphasizes future research needs. It covers annual and perennial feedstocks, and environmental, economic and social aspects. Knowledge gaps and technological options to assess and meet sustainability criteria are reviewed from plot to landscape and global scales. Bioenergy feedstocks present a wide range of dry matter yields, agricultural input requirements and environmental impacts, depending on crop type, management practices, and soil and climate conditions. Their integration into farmers׳ cropping systems poses specific challenges in terms of environmental impacts, but also opportunities for improvements via the use of grass–legume intercropping or residues from biomass conversion processes. Taking into account the spatial distribution of bioenergy crops is paramount to assessing their environmental impacts, in particular, on biodiversity or the food versus energy competition issue. However, few modeling frameworks convey the full complexity of the underlying processes and drivers, whether economic, social or biophysical. In particular, social impacts of bioenergy projects are seldom assessed and there is no methodological consensus. The main research areas identified involve multi-crop and multi-site experiments, along with modeling, to optimize management practices and cropping systems producing bioenergy, possibly on alternative lands and under future climate changes; the design of innovative cropping systems using expert knowledge to ensure suitable integration into farmers׳ cropping systems; the collection of detailed data on the location of bioenergy crops to validate theoretical modeling frameworks and improve sustainability assessment; tackling direct and indirect effects of bioenergy development on land-use changes via coupled economic and agronomical models; investigating the effect of perennial stands on biodiversity in relation to previous land-use and landscape structure; and further developing currently-available methodologies to fully appraise the social implications of bioenergy projects. [Copyright &y& Elsevier]

Abstract: The paper assesses greenhouse gas (GHG) emissions of forest bioenergy supply and utilization in Finland. Each step in the supply chains of harvesting residues (HR), small-diameter energy wood (EW) and stumps (ST) is assessed separately, with geography-related differences between Northern and Southern Finland (NF and SF) taken into consideration. Furthermore, the GHG performance of five distinct bioenergy options—(1) combined heat and power production, (2) condensing power production, (3) torrefied pellets, (4) gasification, and (5) pyrolysis oil production—is assessed and compared with that of current reference systems in Finland and also the European Union (EU) sustainability criteria. If soil carbon stock (SCS) changes and possible storage emissions are omitted, the GHG emissions deriving from the supply chain of comminuted forest biomass to plants are 2.4, 3.0, and 2.6gCO2eqMJ−1 for HR, EW, and ST in SF, respectively. In NF, the corresponding values are 2.9, 3.6, and 3.2gCO2eqMJ−1, respectively. If SCS changes and possible emissions from storage are accounted for, the emissions for HR, EW, and ST are in the ranges 9.2–49.2, 24.4–64.4, and 33.1–73.1gCO2eqMJ−1 in SF and 12.7–52.7, 29.4–69.4, and 39.5–79.5gCO2eqMJ−1 in NF. Most supply-chain GHG emissions arise from SCS changes and possible emissions from storage of comminuted biomass, both of which may involve significant uncertainty factors. In comparison to local reference systems, significant GHG savings can be achieved through energy utilization of forest biomass, but if SCS changes and, in particular, storage emissions are taken into account, fulfillment of the EU sustainability criteria is not guaranteed. [Copyright &y& Elsevier]

Abstract: Obtaining energy through the combustion of biomass proves to be a significant fraction of the total of what has come to be called “renewable energy.” Far from stagnating, energy planning at EU level foresees a considerable increase in this energy sector, so that by 2020 it is expected that renewable energies will form up to 20% of total energy production. Focusing on the bioenergy sector, a problem that may not yet have been sufficiently addressed is the management of waste from the combustion of biomass; however, in the medium to long term it may cause significant effects on the environment, since the majority of it is deposited in landfill sites. This opens up an interesting field of applied research, focused primarily on developing processes which will allow the recycling of these waste materials by putting them to good use and thus prolonging their useful life. This paper presents the basic lines of research carried out by our team in this field, with positive and negative results that may serve for other teams to open new lines of research or to go in greater depth into those already begun. [Copyright &y& Elsevier]

Abstract: Environmental impacts associated with the use of fossil fuels, rising prices, potential limitations in supply and concerns about regional and national security are driving the development and use of biomass for bioenergy, biofuels and bioproducts. However, the use of biomass does not automatically imply that its production, conversion and use are sustainable. Conflicts between various ecosystem services (economic production of food, fodder and fuels, biodiversity, social and cultural values, etc.) that are provided by fertile land are increasing as well. Hence, a developed thinking on how to balance between these services is desirable. There is a significant amount of information available on biofuels and their sustainability. In this paper, different initiatives and sustainability criteria for biofuels are presented and assessed. 35 criteria were found in emerging sustainability assessment frameworks. The majority of 12 criteria were focused on environmental issues, 4 were social and only 1 was economic. Energy balance and greenhouse gas balance were perceived as especially critical, social criteria ranked generally low. Although being perceived as important, food security ranked very low. [Copyright &y& Elsevier]

Abstract: This paper presents an overview of 67 ongoing certification initiatives to safeguard the sustainability of bioenergy. Most recent initiatives are focused on the sustainability of liquid biofuels. Content-wise, most of these initiatives have mainly included environmental principles. Despite serious concerns in various parts of the world on the socio-economic impacts of bioenergy production, these are generally not included in existing bioenergy initiatives. At the same time, the overview shows a strong proliferation of standards. The overview shows that certification has the potential to influence direct, local impacts related to environmental and social effects of direct bioenergy production. Key recommendations to come to an efficient certification system include the need for further harmonization, availability of reliable data and linking indicators on a micro, meso and macro levels. Considering the multiple spatial scales, certification should be combined with additional measurements and tools on a regional, national and international level. The role of bioenergy production on indirect land use change (ILUC) is still very uncertain and current initiatives have rarely captured impacts from ILUC in their standards. Addressing unwanted LUC requires first of all sustainable land use production and good governance, regardless of the end-use of the product. It is therefore recommended to extend measures to mitigate impacts from LUC to other lands and feedstock. [Copyright &y& Elsevier]

Bioenergy is considered a promising alternative to achieve carbon neutrality and emission reduction. There is a debate over the role of bioenergy in climate change mitigation because of carbon emissions from the production and utilization of biofuels. Recently, studies on emissions of biogenic volatile organic compounds (BVOCs) have substantially increased as they have a significant impact on human health and climate change due to large emissions and high reactivity. A scientometric analysis of 2895 journal papers during 1991 and 2020 related to BVOC emissions from the Web of Science Core Collection was conducted by CiteSpace and Carrot2. Results showed that three main knowledge domains were BVOC emissions and drivers, BVOCs and their oxidation products in biosphere-atmosphere exchange, and soil BVOCs in plant-microbe interactions during the period under study. Generally, the relationships between plant BVOC emissions and environmental variables (e.g., temperature, drought, light solar radiation, humidity, availability of nutrients, carbon dioxide, ozone, etc.) can be investigated by measurement techniques (i.e., chamber) or models (i.e., Model of Emissions of Gases and Aerosols from Nature). Soils could work as both the sink and source of BVOCs through various processes that are affected by soil temperatures, pH, organic matter, and moisture. Anthropogenic activities might affect the emission of BVOCs and promote the formation of BVOC-derived pollutants (e.g., ozone, particles, etc.). Incorporating BVOC emissions and their relationships with pollutants, biomass, and energy into environmental management and decision-making is a promising direction. [Display omitted] • A scientometric analysis was conducted on the research evolution of BVOC emissions. • Ten clusters generated by CiteSpace were logically reclassified into three hotspots. • MEGAN is the most frequently empirical model for BVOC emission assessment. • BVOC-derived pollutants like SOA are likely affected by anthropogenic activities. • Soils in terrestrial ecosystems can act as both the source and sink of BVOCs. [ABSTRACT FROM AUTHOR]