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Agricultural crop residues are the lignocellulosic biomass left in the field after harvesting valuable crop parts. These pose a significant concern due to the waste generated annually, burdening management and contributing to pollution. Numerous studies carried out over decades have demonstrated some effective utilization through thermochemical conversion as a potential feedstock, there is not a proper account of their trends. This systematic review addresses a critical gap in the literature by analyzing the sustainable management of crop residues thermochemically, offering insights into research trends, technologies, and future directions for their utilization as biofuel and bioactive value-added-product applications, that has been largely overlooked in previous narrative reviews. Studies for review were searched on web of science, scopus, and google scholar through a carefully developed search syntax and backward snowball methods. Total 343 papers published in past 23 year matched the study inclusion criteria were selected and meaningful outcomes from meticulous analysis of these studies have been extracted. Research publications show exponential growth, primarily focused on laboratory-based experiments. The most studied process was pyrolysis, and the product was biochar. There has been significant progress in process optimization, integration, and product diversification, paving the way for diverse applications. Recent trends indicate a shift from conventional pyrolysis and gasification towards sustainability, circular economy, efficiency enhancements, and novel applications, reflecting a broader commitment to environmental stewardship and resource maximization. Additionally, the challenges linked with recent innovations are discussed, along with recommendations for future research endeavors concerning these systems. [Display omitted] • Systematically reviewed 343 papers on crop residue thermochemical conversion. • Research trends, progress, future prospects and challenges have been discussed. • Optimization, integration, product diversification and applications were major focus. • Exponential research growth, mostly lab-based works on pyrolysis to produce biochar. [ABSTRACT FROM AUTHOR]

Abstract The present work investigates solid biofuel, derived from household food waste (food residue biofuel, FRB) as a potential bioenergy source in cement manufacturing. Up-to-date investigations of household food waste as a solid fuel focused on composition and heating value, yet no results are available regarding impact on plant efficiency and emissions upon utilization. A multidimensional model based on fundamental principles (mass and enthalpy balances) is used together with actual data from fossil fuel operation to identify and quantitatively asses the impacts on plant performance, product quality and atmospheric emissions. Τhe energy needed to prepare low moisture FRBs is determined and suitable processes are singled out. Key issues of cement plant operation are identified and quantitatively assessed via simulation in an actual dry-process plant, when FRBs substitute 20% of thermal energy (provided by petcoke). The facility utilizes 1.65 × 105 tpa of fossil fuels to produce 1.5 × 106 tpa clinker. It is found that energy efficiency falls and clinker production diminishes by about 0.5 t clinker/t FRB. Refractory thermal rating and main blower capacity constraints remain satisfied. Non-biogenic green-house-gas emissions are reduced by ~60 kg/t clinker. Emitted concentrations slightly increase for several pollutants, mainly nitrogen oxides (NO x) hydrogen chloride (HCl) and metals; they decrease for sulphur dioxide (SO 2) and particulates. Maximum emission limits are observed for all regulated pollutants but NO x. Incombustible chlorine and inclusions of alkalis in cement increase by ~9%. To reap the bioenergy benefits and mitigate impacts, blends of FRB (~80%wt) with paper residues (~20%wt) are investigated. Conforming to plant operational constraints and product specifications, the blends ensure production level, environmental compliance and reduced emission rates. The results direct towards customer-tailored FRB blends with lignocellulosic residues, that best suit the design, specific quarry raw materials, operating conditions and individual parameters of the cement plant towards more sustainable cement manufacturing. Highlights • Food waste can be valorized to biochemicals and biofuels, including solid fuels. • Drying to ≤ 15% moisture gives stable, nonhazardous food residue biofuels (FRBs). • Substitution of petcoke by FRBs in cement kilns decreases clinker level. • Lower CO 2 , SO 2 and mercury but higher chlorines and NO x emissions result. • Superior blends of FRB with paper residues improve clinker production and emissions. [ABSTRACT FROM AUTHOR]

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]

With the rising population in India the demand for energy is also shooting up. This paper examines the potential, scope and the opportunities of biomass in the Indian economy. India, being an agricultural country, has a lot of possible resources from the agronomic sector like crop residue, animal manure, etc., which has not been utilised in an efficient way. This paper also gives an insight into anaerobic digestion and the many other digesters implemented in India. The accelerating economic growth leads to the rapid rise in urbanisation which in turn generates an increased production of Municipal Solid Waste (MSW). This MSW can be used in biomass production in quite a lot of innovative ways. The study also focused on the potential sources and their proper conversion technique. The feasibility of biomass conversion and achievements made by India was also looked into. Use of bioenergy in cheaper and economically feasible ways is also a practical solution to the energy crisis. [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]

Bioenergy conversion technologies have been frequently described and analysed in the literature, but a comprehensive and detailed comparison between the complex individual characteristics of each technology is still lacking. Therefore, the paper contains a description of the technical, economic and environmental properties of each technology with a special focus on the German bioenergy sector. The study presents an analysis of different bioenergy applications with regard to their specifications, power/heat output range and their areas of application. Due to the fact, that biomass combustion applications are the most widespread and market proven renewable conversion technologies, a detailed analysis of decentralised, biomass-fired CHP plants is presented in the paper. The overview of the individual characteristics of different biomass conversion routes shows that biogas plants achieve high electrical efficiencies, are available with a broad range of capacities and belong to the established technologies. Although the investment costs of biogas plants are relatively high, biomass conversion with anaerobic digestion can be seen as one of the most promising option for a sustainable energy supply in Europe. [ABSTRACT FROM AUTHOR]

Abstract: With increasing attention on energy shortage and global warming, bioenergy is a promising alternative energy to mitigate CO 2 emissions. Despite the environmental friendly potential, a certain quantity of bioenergy-related CO 2 is still emitted in China. This paper investigates the temporal dynamics of bioenergy-related CO 2 emissions in 2000–2010 in China, and explores the underlying influence factors based on logarithmic mean Divisia index (LMDI). Then the core results are verified with a GIS-based approach from a spacial perspective. The results show that four impact factors: emission intensity, energy structure, energy efficiency and economic development have different impacts on bioenergy-related CO 2 emissions, of which economic development is the major factor contributing to its increase, while energy efficiency is the major determinant for the decline. Per capita bioenergy-related CO 2 emissions in different areas are verified in accordance with either economic development factor or energy efficiency factor to some extent. To achieve the dual purpose of sustainable development and CO 2 emissions reduction, this paper provides a practical policy framework for rural bioenergy and economic development. [ABSTRACT FROM AUTHOR]

This paper provides a critical review on the current status and potential of biomass utilization in ferrous metallurgical processes, i.e., the blast furnace (BF) – basic oxygen furnace (BOF) route, the direct reduction (DR) – electric arc furnace (EAF) route, the scrap – EAF route and the other routes. In the BF-BOF route, biomass can be used as a fuel for iron ore sintering, or as a raw material for the production of bio-coke, and utilized for blast furnace injection. In the DR-EAF route, direct reduction iron can be produced form iron ore and biomass pellet. In the scrap – EAF route, biomass can be utilized in EAF through a cogeneration system. In addition, biomass can be utilized in magnetic separation of refractory low-grade iron ore, in reuse of iron and steel slag, or as an adsorbent for pollutant control, etc. The challenges and outlook of biomass utilization in metallurgical industry are also discussed in this paper. [ABSTRACT FROM AUTHOR]

The transport sector, which heavily depends on oil-derived liquid products such as gasoline and diesel, globally occupies the 3rd place when total energy consumption and greenhouse gas (GHG) emissions are considered (after the industry and the building sectors). This consumption level is predicted to increase by 60% by 2030 mainly because of population growth, industrialization and exposure to better living standards. Biodiesel is one of the sustainable sources of energy for meeting increasing global transport energy demand and reducing GHG emissions significantly. The use of non-edible plant oils is very significant because it can be grown in harsh and marginal lands which require less maintenance, less soil fertility and less water as opposed to arable lands for growing edible vegetable oils. However, it is noted that the 2nd generation feedstocks can also be grown in arable lands, but this is not a general practice and is not recommended. The 2nd generation biodiesel can be considered as a promising alternative because of its feedstocks, such as non-edible vegetable oils, animal fats and waste cooking oils are cheaper in most of the countries in the world than the 1st generation feedstocks which are produced from edible-vegetable oils (food crops). Furthermore, the price of biodiesel depends on the cost of feedstocks which makes up 70–95% of the total production costs. However, extraction of non-edible oils as well as conversion process of oil into biodiesel should be well scrutinized. This paper extensively reviews on the selection of 2nd generation biodiesel feedstocks, oil extraction as well as biodiesel conversion techniques with the aim to identify the most appropriate and cost-effective feedstocks, identify the most suitable oil extraction technique and most efficient technology for producing of the 2nd generation biodiesel which will substitute the current dependence on the fossil fuel worldwide. This paper will contribute to greater understanding of the recent development and prospects of 2nd generation biodiesel as a sustainable transport fuel. [ABSTRACT FROM AUTHOR]

The use of renewable energy is projected to increase substantially in the European Union to reach a share of 20% in final energy consumption and 10% renewable energy in transport by 2020. The renewable energy contribution is further expected to increase to 55%–75% of gross final energy consumption in 2050. According to the latest reports, the European Union has made significant progress since 2005 and is on track to reach its 2020 renewable energy targets. This paper provides a review of the policy framework for renewable energy in the European Union and an analysis of the progress made by the use of renewable energy as well as the expected developments until 2020 and beyond. It focusses on the contribution of bioenergy, the major source among renewables in the European Union. As biomass availability is a critical issue for the bioenergy production, this paper provides an analysis of the biomass demand for reaching the 2020 targets, in relation with the expected domestic supply and biomass potential. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is a viable technique to address food waste (FW) problems by converting FW into sustainable energy. Despite the advantages of the AD process, large-scale AD plants like in Germany and the USA have not been developed in Australia. Therefore, this paper aims to study the technological, economic, and environmental feasibility of sustainable energy production from household FW in Australia. In addition, this paper discusses the different waste to energy (WtE) technologies along with the operational parameters as well as the challenges in developing a biogas plant. The energy and economic potential analysis of the AD process indicates that the processing of 10% FW from Australian states and territories can generate 1.22 GWh to 35.4 GWh electricity which can subsequently earn AUD 0.54 million to AUD 15.7 million revenue per year. The greenhouse gas (GHG) emissions analysis indicates that conversion of the 10% of Australian FW has the potential to lower GHG emissions by 639,852 tonnes per annum. Hence, it can be said that FW plays a vital role as a promising source of sustainable energy and is capable of benefiting the country's economy significantly and reducing GHG emissions. • FW is a potential source of sustainable energy. • AD is a useful waste to energy process for producing clean energy. • Conversion of FW into energy can significantly lower GHG emissions. [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]

Abstract: Biomass supply chain optimisation is essential to overcome barriers and uncertainties that may inhibit the development of a sustainable and competitive bioenergy market. The number of research papers presenting optimisation models in the field of bioenergy systems rises exponentially. This paper gives an overview of the optimisation methods and models focussing on decisions regarding the design and management of the upstream segment of the biomass-for-bioenergy supply chain. After a general description of the supply chain and the decisions coming along with the design and management, all selected publications are classified and discussed according to (1) the mathematical optimisation methodology used, (2) the decision level and decision variables addressed and (3) the objective to be optimised. This classification allows users to identify existing optimisation methods or models that satisfy specific requirements. Moreover, the factual description of the presented optimisation methods and models points to opportunities for development of an integrated, holistic approach to optimise decisions in the field of biomass supply chain design and management. Such approach must be based on the consideration of the interrelationships and interdependence between all operations in the entire biomass-for-bioenergy supply chain. [Copyright &y& Elsevier]

Abstract: Biomass supplies about 66% of total energy consumption in Zimbabwe. In recent times there has been an increasing interest in the country to increase the utilization of biomass resources for energy purposes. The major biomass materials found in Zimbabwe are fuelwood, crop and forestry residues, animal dung, energy crops, municipality and industrial wastes. Biomass energy conversion technologies include anaerobic digestion, pyrolysis, gasification, transesterification, fermentation and combustion. The premise of this paper is that as a component of a renewable energy mix, biomass should play an important role in sustainable energy systems in Zimbabwe. With an estimated total energy value of 409pJ, biomass is a huge energy resource for the country and must be optimally exploited. However, traditional utilization of solid biomass materials as a primary source of energy continues to be prevalent in Zimbabwe today. The trend should be to move from traditional biomass energy to improved and modern biomass energy technologies. This is evidenced by numerous projects that have been undertaken in pursuit of this endeavor. The aim of this paper is to review the state of biomass energy technologies in Zimbabwe with a view to provide aggregated information that will inform research, development and policies related to biomass energy. [Copyright &y& Elsevier]

Abstract: Biofuels are identified as the potential solution for depleting fossil fuel reserves, increasing oil prices, and providing a clean, renewable energy source. The major barrier preventing the commercialization of lignocellulosic biorefineries is the complex conversion process and their respective supply chain. Efficient supply chain management of a lignocellulosic biomass is crucial for success of second generation biofuels. This paper systematically describes energy needs, energy targets, biofuel feedstocks, conversion processes, and finally provides a comprehensive review of Biomass Supply Chain (BSC) design and modeling. Specifically, the paper presents a detailed review of mathematical programming models developed for BSC and identifies key challenges and potential future work. This review will provide readers with a starting point for understanding biomass feedstocks and biofuel production as well as detailed analysis of the BSC modeling and design. [Copyright &y& Elsevier]

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]

Abstract: This paper assesses the learning potential of dedicated wood production systems to boost yields and reduce production costs. In particular, the paper analyses past trends and provides a future outlook of developments in dedicated wood production for three cases: eucalyptus production in Brazil, poplar production in Italy and willow production in Sweden. A main objective of this paper is to evaluate the extent to which experience curves can be devised for conventional woody plantation systems, and whether these can also be applied to short rotation cropping (SRC) production systems. For current average SRC production systems, Italian poplar shows the highest cost at 5.5 €GJ−1 followed by Swedish willow at 4.4 €GJ−1 and Brazilian eucalyptus is produced to the lowest costs at 2.8 €GJ−1. It was assessed to what extent production costs can be reduced per step in the production cycle and how this affects the minimum cost levels that can ultimately be achieved. Ultimate cost reduction could lead to delivered costs of 2.2 €GJ−1 for poplar, 1.9 €GJ−1 for willow and 1.9 €GJ−1 for eucalyptus on better quality lands. Based on historic cost data and production trends, experience curves were applied providing progress ratios for poplar in Italy and eucalyptus in Brazil. Brazilian eucalyptus production follows a steeper slope (63–73%) than poplar in Italy (71–78%). The extent to, and rate at, which cost reductions can occur within the next 20 years were evaluated by combining current costs, minimum cost levels and progress ratios with ranges in European and global biomass demand projections. This shows that, at the assumed growth rates for biomass production in Europe and for global production, minimum cost levels can be reached within the next two decades for all cases. [Copyright &y& Elsevier]

Conservation and restoration are crucial to maintaining a wide range of functions and services in wetlands, but it is difficult to find a reasonable and resource-efficient management option without sacrificing ecological values. In the present paper, we analyse the variability and dynamics of the chemical composition and energy potential of biomass from reedbeds, floodplain meadows, coastal meadows and reed canary grass cultivation in extracted peatlands. We observed that the chemical characteristics that are crucial for bioenergy production vary by biomass origin and over time. The bioenergy potential depends on biomass production and on the conversion method. The results indicate that the energy potential ranges from 122 to 190 GJ/ha per year in semi-natural floodplain meadows in the boreal zone. About 160 GJ/ha per year can be obtained from natural reedbeds but only about 120 GJ/ha per year from cultivated extracted peatlands. Using methane conversion, we can obtain only about 50%, and using ethanol conversion we can obtain less than 20% of the total energy potential of the herbaceous biomass of floodplain meadows. Although long-term studies on homo- and heterogeneous biomass production are required, we conclude that the local biomass of natural, semi-natural and artificial wetlands could contribute significantly to sustainable development. • Bioenergy production is higher in natural vegetation than in cultivated wetlands. • Carex spp. and Filipendula ulmaria are alternatives for wetland restoration. • Chemical composition and methane potential differ by biomass origin and over time. • Floodplain meadows have the highest energy potential among boreal zone wetlands. • Biofuel yield is higher through methane than through ethanol conversion. [ABSTRACT FROM AUTHOR]

Renewable energy sources can help combat climate change but knowing the land, water and carbon implications of different renewable energy production mixes becomes a key. This paper systematically applies land, water and carbon footprint accounting methods to calculate resource appropriation and CO 2 eq GHG emissions of two energy scenarios. The '100% scenario' is meant as a thinking exercise and assumes a complete transition towards bioenergy, mostly as bioelectricity and some first-generation biofuel. The 'SDS-bio scenario' is inspired by IEA's sustainable development scenario and assumes a 9.8% share of bioenergy in the final mix, with a high share of first-generation biofuel. Energy inputs into production are calculated by differentiating inputs into fuel versus electricity and exclude fossil fuels used for non-energy purposes. Results suggest that both scenarios can lead to emission savings, but at a high cost of land and water resources. A 100% shift to bioenergy is not possible from water and land perspectives. The SDS-bio scenario, when using the most efficient feedstocks (sugar beet and sugarcane), would still require 11–14% of the global arable land and a water flow equivalent to 18–25% of the current water footprint of humanity. In comparative terms, using sugar or starchy crops to produce bioenergy results in smaller footprints than using oil-bearing crops. Regardless of the choice of crop, converting the biomass to combined heat and power results in smaller land, water and carbon footprints per unit of energy than when converting to electricity alone or liquid biofuel. • The greenhouse gas emission savings of bioenergy entail large land and water use. • Land, water and carbon footprints of biofuels and bioelectricity are calculated. • A dynamic energy feedback loop is used to clarify gross and net footprints. [ABSTRACT FROM AUTHOR]

Sludge management is still one of the most challenging issues in wastewater treatment plants due to a dramatic increase in sludge production, high sludge disposal costs, legal constraints as well as social and environmental concerns. There is a great effort to develop more environmentally friendly and economical technologies for minimization of excess sludge production and converting wastewater treatment sludge from waste into a renewable resource for bioenergy recovery. Recently, among these technologies, pretreatment processes applied before anaerobic sludge digestion have received a growing attention with several advantages over conventional digestion process. The main goal of the present paper is to present a state-of-the-art review of recent developments on advanced anaerobic digestion employed in municipal wastewater treatment plants. Thermal pretreatment technologies documented in the literature are presented extensively. The effectiveness of thermal pretreatment methods, namely conventional, microwave and radio frequency heatings, are discussed and compared in terms of heating principles, sludge disintegration, digester performance, and sludge rheology. The effectiveness and practicality of the aforementioned methods at industrial-scale and some challenges associated with the implementation at full-scale are also reviewed. Particular attention is paid to integration of combined heat and power systems with thermal hydrolysis for achieving energy self-sufficiency in full-scale plants. Furthermore, the municipal sludge production around the world as well as current sludge disposal and reuse options are addressed. • Sludge generation and characteristics specific to unit processes are reviewed. • Sludge pretreatment with waste heat achieves the highest net energy generation. • Sludge pretreatment with microwave irradiation is not feasible at full-scale. • Radio frequency has emerged as an energy-efficient electromagnetic pretreatment. • There are still challenges with electromagnetic sludge pretreatment at full-scale. [ABSTRACT FROM AUTHOR]

Abstract The Canadian province of Quebec has set for 2030 a greenhouse gas (GHG) emission reduction target of 37.5% below 1990 levels. Meeting such a reduction target requires in particular a rapid transition to a low-carbon energy system. This paper proposes prospective energy scenarios for Quebec up to 2030, under different GHG emission reduction constraints (up to a 40% reduction). The main objective is to explore the role of bioenergy in achieving the reduction targets. Our analysis is based on the North American TIMES Energy Model (NATEM). It belongs to the MARKAL/TIMES family of models supported by the International Energy Agency, and includes a detailed bioenergy sector. Compared to the reference case (baseline), our results indicate a larger share of bioenergy in 2030 (up to a threefold increase in the most stringent GHG reduction scenario), with up to a fourfold increase in the total amount of feedstock used for bioenergy production. Our study envisions thus a much larger penetration of bioenergy than the one proposed by the government of Quebec in its 2030 Energy Policy. Highlights • Prospective energy scenarios for the Province of Quebec under GHG reduction targets. • Use of a TIMES optimization energy model to derive socially optimal solutions. • Explore the role of bioenergy in achieving the reduction targets. • Results indicate a larger penetration of bioenergy than the one proposed by the government of Quebec in its 2030 Energy Policy. [ABSTRACT FROM AUTHOR]

Abstract Studies of the production and use of biomass of perennial plants as energy feedstock have been conducted by Polish researchers for over 20 years. One genus of particular interest is Salix spp. L., which occurs naturally in the temperate zone. Experiments concerning the productivity of willow have been conducted mainly on small-scale experimental fields, but there have been studies conducted on large-scale, experimental and commercial plantations. An analysis of the scientific literature found that the mean willow biomass yield was 8.5 Mg ha−1 y−1 d.m. The mean productivity on small-scale experimental fields (11.4 Mg ha−1 y−1 d.m.) was much higher than on large-scale fields (5.7 Mg ha−1 y−1 d.m.), by 4.5, 7.2 and 7.5 Mg ha−1 y−1 d.m. for biennial, triennial and quadrennial harvest cycles, respectively. Meanwhile, when the optimum yield-generating agents were applied (such as cultivar/clone, fertilisation rate or planting density) higher yields were achieved (by 48% and 72%) in small and large-scale experiments, respectively. Considering only the harvest cycle, the highest mean productivity was achieved in the longer cycles, triennial for small-scale experiments and biennial and triennial for large-scale experimental and commercial plantations. Studies conducted using small-scale experiments still play a very important role in the initial phase of studies on the yield-generating factors under analysis and enable their verification in multiple combinations. Meanwhile, farmers and researchers, as well as national policy-making institutions, value data from commercial plantations. However, there have been few papers published so far on the productivity of such plantations in Poland, particularly those describing studies conducted in similar soil conditions in successive harvest cycles. Moreover, studies should be conducted at sites with poor quality soil, i.e. intended for growing energy crops, where the yield is usually smaller than on good soils used in agriculture for the production of food and fodders. Graphical abstract fx1 Highlights • Studies of the productivity of willow were conducted in Poland for over 20 years. • Various clones and cultivars were tested in 1-, 2-, 3-, 4- and 5-year cycles. • The mean yield of willow in small-scale experiments was 11.4 ± 6.0 Mg ha−1 y−1 d.m. • The highest yield was achieved in 3-year harvest cycles. • The mean yield in large-scale experiments was smaller by 50% than in small-scale. [ABSTRACT FROM AUTHOR]

Abstract With their fast growth rate and ability to accumulate a high percentage of their weight as lipid and carbohydrate, microalgae potentially represent an ideal feedstock for the production of biodiesel and bioethanol. In addition, microalgae offer several environmental benefits, and do not compete with food production for land, fresh water, and nutrients. Therefore, the main goal of this work is to provide a quantitative, systematic and harmonized assessment of current bio-energy potential. The analysis is conducted by considering all the main steps in detail, from cultivation to biodiesel production, and by deriving an overall estimation of energy consumption for biodiesel production. Energy consumption uncertainty is also quantified and discussed. A systematic review of all the main technologies available for all the main processing steps towards the production of biodiesel from microalgae is presented, focusing on the derivation of the Net Energy Ratio (NER) of each combination of technologies, complemented by an uncertainty analysis of the data used and those obtained in the present work. A wide scatter in the data available in the literature has been identified, highlighting the need for an uncertainty analysis. If the average overall energy consumption per unit of biodiesel mass is considered, all the routes adopting a raceway pond have a lower energy consumption, but if the uncertainty on the overall energy consumption is also considered, the minimum value of the range of NER values for some of the routes adopting a photobioreactor is comparable to the NER value obtainable by using raceway ponds. Thus, the present framework proposes a harmonized and comprehensive methodology to compare and contrast technologies for the production of biodiesel from microalgae, and is applied in this paper to identify, with an appreciation of the uncertainty, the most promising combinations of technologies. Highlights • Quantitative, systematic and harmonized assessment of microalgae energy potential. • A step-by-step analysis and overall estimation of energy consumption is given. • A substantial uncertainty on the data in literature has been identified. • The energy consumption uncertainty is quantified and critically discussed. • Derivation of the Net Energy Ratio (NER) for each combination of technologies. [ABSTRACT FROM AUTHOR]

Abstract: As the world confronts a reported food shortage and rising fuel prices, scientists around the globe are scrambling to develop biofuel feedstocks that would not divert food crops to energy. It is apparent that the demand for biodiesel is expected to increase in near future and although many edible oils might be the cheapest feedstock for biofuel production. But it may not be sustainable source to meet this increasing demand. This justifies the need to use non-edible oil seeds that can be the reliable sustainable feedstock for biofuel production. Furthermore, most of the non-edible seeds bearing trees have the potentials of reclaiming wasteland and does not compete with food crop for limited growing regions. It thus becomes imperative to search for dedicated non-edible feedstocks and their suitability for biodiesel production. This paper attempts to make an assessment of current energy scenario, potential of non-edible oil over edible oils, selected non-edible oil seeds as biodiesel feedstocks, impact of biofuel on environment and future direction. Experimental analysis by different researchers on these non-edible oils showed their great potential as feedstocks for biodiesel production. This paper also reviews the biology, distribution and chemistry of selected non-edible oil seeds plants. [Copyright &y& Elsevier]

Abstract Storage is the critical operation within the biomass supply chain to reduce feedstock supply risks and to manage smooth year-around operations of a biorefinery or a bioenergy plant. This paper analyzed the economic and environmental impacts of four different biomass storage systems for woodchips (Outdoor-open, Outdoor-tarped, Indoor, and Silo) and two systems for pellets (Indoor and Silo). Storage cost includes the costs for handling (including ventilation in case of silo storage), infrastructure investment, and dry matter loss (DML) for each system. The estimation of total greenhouse gas (GHG) emissions includes the fugitive emissions from storage piles and emissions due to electricity and fuel consumption for each system. Among four storage systems, the outdoor-tarped ($15.0 ODMT−1, ODMT: Oven Dry Metric Ton) and silo ($5.8 ODMT−1) storage were the least-cost options for woodchips and pellets respectively. However, silo-storage could be the most promising option for storing woodchips ($5.8 ODMT−1) and pellets ($2.3 ODMT−1), if it is used for short-term (two months) and frequently (at least six times) in a year. The total GHG emissions for six-month storage were 2.8–11.8 kgCO 2 e ODMT−1 for woodchips and 8.6–42.0 kgCO 2 e ODMT−1 for pellets. During Outdoor-open storage, the lower heating value of woodchips could drop to 37% due to increased dry-matter loss (DML) and moisture content. The initial moisture content, bulk density, DML, and resource required during handling were the most sensitive parameters influenced the storage performances of both woodchips and pellets. This study has demonstrated that a combination of different storage options along the supply chain could reduce the total biomass storage cost for a biorefinery or power plant. Graphical abstract fx1 Highlights • Large-scale storage options for storing woodchips and pellets were studied. • The outdoor-open storage was the least-cost option for long-term storage of woodchips. • Bin/silo storage was the best option for short-term storage of woodchips and pellets. • The average bin storage cost ranged from 2 to 22 ODMT−1. • All storage systems had low energy use and GHG emissions. [ABSTRACT FROM AUTHOR]

Recently, biomass represents about 14% of primary energy consumption and expected to provide 50% of world total primary energy consumption by 2050. This paper clarifies an appraisal of the possibilities available in Egypt to become one of the countries of the production of bioenergy, especially from the crop remnants of agriculture production. Egypt annually produces a large amount of biomass of up to 40 million tons. Unfortunately, instead of the possibility of exploiting these wastes to contribute to the energy sector and economic growth, about 52% of these wastes are disposed of by direct burning, which may cause many environmental problems. The only widespread form of biomass use in Egypt is biogas used in rural areas. In addition, the potential theoretical energy from the most important crop residues available in Egypt is evaluated according to previous studies. It is found that energy of 189.76 PJ/year can be produced from dry crop residues of 12.5 million tons/year. For livestock residues, specifically cattle manure, it is estimated in this study that the potential biogas in Egypt of 7.2 million head of cattle is 53.2 million m 3 / day with a total potential energy of 699 TJ per year. However, the potential of bioenergy depends largely on the availability, geographical distribution and accessibility of the actual waste. The most likely areas for these potentials are Middle Delta and Upper Egypt. This could potentially develop a long-term strategy for the smart use of vital waste available for bioenergy production to be economically profitable and sustainable. [ABSTRACT FROM AUTHOR]

Agricultural solid biomass has been widely recognized as an important source of renewable energy with huge production potential. The utilisation of agricultural solid biomass as feedstock for energy production is continuously growing all over Europe. As shown in the current country's balance of energy production and consumption, Croatia is highly dependent on imported fossil fuels. The aim of this paper is to determine the available agricultural solid biomass and its energy potential in Croatia. The quantity and energy potential of solid biomass refer to post-harvest residues, pruning residues, agro-industrial solid waste and biomass from Miscanthus energy crop. In relation to potentially available agricultural biomass, three scenarios have been developed (progressive – S1, optimistic - S2, and conservative – S3) of introducing solid biomass in the renewable energy production sector. On the basis of these scenarios, it can be concluded that in Croatia the following quantities of agricultural biomass are available: 3050.3 t (S1); 1441.8 t (S2); and 733.68 t (S3). These quantities give energy potential of 51.14 PJ (S1), 24.06 PJ (S2), and 12.18 PJ (S3) respectively. [ABSTRACT FROM AUTHOR]

Abstract: An energy resource that is renewed by nature and whose supply is not affected by the rate of consumption is often termed as renewable energy. The need to search for renewable, alternate and non-polluting sources of energy assumes top priority for self-reliance in the regional energy supply. This demands an estimation of available energy resources spatially to evolve better management strategies for ensuring sustainability of resources. The spatial mapping of availability and demand of energy resources would help in the integrated regional energy planning through an appropriate energy supply–demand matching. This paper discusses the application of Geographical Information System (GIS) to map the renewable energy potential talukwise in Karnataka State, India. Taluk is an administrative division in the federal set-up in India to implement developmental programmes like dissemination of biogas, improved stoves, etc. Hence, this paper focuses talukwise mapping of renewable energy (solar, wind, bioenergy and small hydroenergy) potential for Karnataka using GIS. GIS helps in spatial and temporal analyses of the resources and demand and also aids as Decision Support System while implementing location-specific renewable energy technologies. Regions suitable for tapping solar energy are mapped based on global solar radiation data, which provides a picture of the potential. Coastal taluks in Uttara Kannada have higher global solar radiation during summer (6.31kWh/m2), monsoon (4.16kWh/m2) and winter (5.48kWh/m2). Mapping of regions suitable for tapping wind energy has been done based on wind velocity data, and it shows that Chikkodi taluk, Belgaum district, has higher potential during summer (6.06m/s), monsoon (8.27m/s) and winter (5.19m/s). Mysore district has the maximum number of small hydropower plants with a capacity of 36MW. Talukwise computation of bioenergy availability from agricultural residue, forest, horticulture, plantation and livestock indicates that Channagiri taluk in Shimoga district yields maximum bioenergy. The bioenergy status analysis shows that Siddapur taluk in Uttara Kannada district has the highest bioenergy status of 2.004 (ratio of bioresource availability and demand). [Copyright &y& Elsevier]

Abstract: Greenhouse gases (GHGs) emissions are becoming significant energy and environmental issues relating to municipal solid waste (MSW) deposited in landfills in Taiwan. The nation, although not a Party to the Montreal Protocol and Kyoto Protocol, has diligently striven to mitigate and phase out them. The landfill gas (LFG), which is now considered as a renewable energy with emphasis on electricity generation, has been recognized as one of the main GHGs emissions associated with its composition mostly consisting of methane (CH4) and carbon dioxide (CO2). The objective of this paper is to present an updated overview of LFG-to-electricity in Taiwan. The description is thus centered on biogas sources and their energy utilizations, and then aimed at MSW generation and management. Using the International Panel on Climate Change (IPCC) recommended methodology, anthropogenic methane emissions from MSW landfills in Taiwan during 1992–2003 were estimated to be around 360 thousand metric tons annually during 1992–1999, then decreased to approximately 103 thousand metric tons in 2003 due to the MSW recycling and incineration policies during this period. The promotion measures relating to LFG-to-electricity are also summarized in the paper. Finally, we overview four LFG-to-electricity facilities currently commercialized in Taiwan, and briefly evaluate their economic and environmental benefits. It is shown that total LFG-to-electricity is around based on the LFG generation rate of , heating value of 5500 kcal/m3, and energy efficiency of 25%. [Copyright &y& Elsevier]

Nowadays, reducing the environmental impact of biorefinery is a common concern of scholars. life cycle assessment (LCA) is a widely used method to evaluate the environmental impact of biorefinery. Considering the lack of a latest review on the progress and existing problems related to biorefinery based on LCA studies, this paper carried out a systematic review of the evaluation of environmental impact of biorefinery based on LCA, and proposed the development strategies for waste biorefineries by targeting literature on LCA methods. After finding out the imperfections existing in the current researches, the paper then constructed a comprehensive and systematic biorefinery framework with a standard LCA employed as a reference template for following researches. 92 peer-reviewed articles published in Web of Science, Springer and Scopus from 2015 to 2019 with LCA and biorefinery as the keywords were considered. The key findings are as follows: (1) Agricultural waste and industrial residues are the top two feedstocks widely employed, accounting for 32.61% and 29.35% respectively; (2) the primary data is scarce. The foreground data of LCA is 56.52% from the researches of other scholars; (3) the LCA methods are not standardized. 30.26% and 18.42% have unclear system boundaries and functional units; and (4) there is a lack of estimating the influences of various uncontrollable external factors in the biorefinery process. Furthermore, the review highlighted and discussed the defects of biorefineries, a robust LCA template that can be used for evaluating the environmental impact of biorefinery was constructed, taking algae biorefinery as an example. Image 1 • 92 research articles on LCA and biorefinery are reviewed to update the latest progress. • Major issues on employing life cycle assessment for facilitating sustainable biorefinery are uncovered. • The environmental impacts of widely used biorefinery feedstocks and technologies are compared. • Recommendations for future biorefinery-driven LCA are proposed from five aspects. • A demonstration model on the biorefineries with LCA was exemplified. [ABSTRACT FROM AUTHOR]

Environmental, economic and political pressures have driven the interest towards the search of sustainable feedstock for biofuel production. At present, macroalgae (green, brown and red marine seaweed) is getting growing consideration as an alternative resource for sustainable biomass to produce biofuels, biochemical and food. The unique chemical composition and wide variation in the availability create various opportunities and also challenges for bio-based energy production. Recently, numerous studies have taken place in the exploitation of seaweed as carbon sources for the bioethanol production. Thus, this paper attempts to highlight the characteristics, processing techniques and potential applications of the seaweed. The present review also focuses on recent innovative approaches for the sustainable production of bioenergy from seaweed. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to analyse the efficiency of the plantlet production of Virginia fanpetals, to make economic calculations for their energetic use and to determine the most favourable plant density. According to the experiments, the cost of a healthy Sida plantlet is in the range of 38.4 − 60.6 Euro cents, using the nurse-in-tray technology (NIT). This cost range is much lower than the market prices of the plantlets and the production method is more reliable compared to sowing. In the second year, the dry matter yield originating from Sida plantlets was 10.2 – 11.9 t hectare −1 (ha) without fertilisation in the different planting densities. However, in the longer term, it is recommended to apply organic manure regardless of spacing. The theoretical market value of Sida is generally higher than total unit costs (36 − 60 EUR t − 1 ) in the case of all methods used, except for biogas. The production of Sida can be economical for farmers farming in marginal conditions, using locally available organic manure, producing crops with high heat demand, or involved in beekeeping. [ABSTRACT FROM AUTHOR]

This paper propose the inclusion of a raw material in Brazilian fuels sector. The corn is used in other countries to produce ethanol, in Brazil has other business demands, not being employed as proposed. The work also highlights the energy, economic, social and environmental role in production ethanol from corn, especially for the country´s development, minimizing losses in logistics and grain exports. Comparatively corn is more expressive as bioenergy associated with sugarcane in the Brazilian conditions, because other raw materials have limitations: sugar beet does not have viable cultivation; rice, cassava and wheat are insufficient; and sweet sorghum requires technological adjustments to have significant production. The co-products that arise from the production of ethanol are nutritionally rich, causing less pressure on corn commodities trading. [ABSTRACT FROM AUTHOR]

In order to understand the climate effects of a bioenergy system, a comparison between the bioenergy system and a reference system is required. The reference system describes the situation that occurs in the absence of the bioenergy system with respect to the use of land, energy, and materials. The importance of reference systems is discussed in the literature but guidance on choosing suitable reference systems for assessing climate effects of bioenergy is limited. The reference system should align with the purpose of the study. Transparency of reference system assumptions is essential for proper interpretation of bioenergy assessments. This paper presents guidance for selecting suitable reference systems. Particular attention is given to choosing the land reference. If the goal is to study the climate effects of bioenergy as a part of total anthropogenic activity the reference system should illustrate what is expected in the absence of human activities. In such a case the suitable land reference is natural regeneration, and energy or material reference systems are not relevant. If the goal is to assess the effect of a change in bioenergy use, the reference system should incorporate human activities. In this case suitable reference systems describe the most likely alternative uses of the land, energy and materials in the absence of the change in bioenergy use. The definition of the reference system is furthermore subject to the temporal scope of the study. In practice, selecting and characterizing reference systems will involve various choices and uncertainties which should be considered carefully. It can be instructive to consider how alternative reference systems influence the results and conclusions drawn from bioenergy assessments. [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]

Renewable energy projects have been launched throughout Mexico in order to deliver clean and affordable energy worldwide. The aims of this research are: (i) to know the current status of electricity generation through solar, wind, biomass, geothermal, and hydropower in Mexico, (ii) to determine the renewable energy potential in Mexico and its generation schemes, and (iii) to analyze the social and environmental challenges that these technologies are going to face in Mexico. This paper highlights for the first time a comprehensive review of the current status of renewable energy projects for electricity generation in Mexico and the potential impact of these technologies in the social and environmental areas. The results presented are based on a critical review of the energy policy and regulation, as well as statistical data on electricity generation in Mexico. It was found that in Mexico 62 GW h/year were generated by solar photovoltaic technology of which 49 GW h/year were produced by 6 private projects and 13 GW h/year by 2 generating plants of the Federal Electricity Commission (CFE). There is a proven potential to generate 16,351 GW h/year through solar energy. Although the proven potential for wind power generation in Mexico is 19,805 GW h/year, wind power is exploited by onshore technology, with a generation of 7675 GW h/year of which the CFE produced 220 GW h/year through 3 generating plants, while 27 private producers generated 7455 GW h/year. In Mexico, the main renewable technologies used to generate electricity are hydropower, onshore wind farms, and geothermal. Mexico has a great potential to generate electricity from renewable sources, however the government must encourage its use through the appropriate mechanisms in order to achieve its proposed goals of generating 35% of total electricity from clean sources by 2025, improve the social welfare, and shape a sustainable future. [ABSTRACT FROM AUTHOR]

Portugal relies to a very large extent on imports to meet its energy needs. The predominant energy source is oil, which comes in its entirety from other countries. Renewables now are the second most important energy source being hydropower the most important domestic source of energy. Since more than one third of the territory is forests, biomass is one of the most potential renewable energy sources. This paper presents the scope, potential and technologies related to the use of biomass resources. The study also discusses the biomass projects undertaken by the government and non-government organizations, plans and strategies to promote the biomass. The current status of biomass resources shows that the total potential estimated for various sectors of the country is of 42,489.7 GW h/year. The study also reveals one overexploited biomass resource such as forest biomass (if all the predicted biomass power plants enter into the running phase) and underexploited biomass resources such as municipal solid wastes, waste waters and animal manures. The future prospects for biomass are the embodied in the EU and national strategies for the RES sector, which estimates an average annual growth of 5% for installed capacity and 1% for the power production. [ABSTRACT FROM AUTHOR]

Microalgae have gained increased attention as a viable, eco-friendly and alternative source of green bioenergy. To compete in the fuel market, saline microalgae cultivation for biofuel production would need to be economically sustainable and co-cultivation of saline microalgae using only saline water and recycled nutrient can potentially be the best solution to reduce the excessive use and prompt downsizing of natural resources like fresh water and fertilizers. This review provides a critical analysis on the selection of potential biofuel producing marine, halotolerant and halophilic microalgae. Here we proposed a microalgae co-cultivation strategy from seawater salinity (35ppt) to salt saturation (300ppt) with biofuel as the main output. We focused that adaptation of a co-cultivation strategy could reduce 95%, 74% and 51% of the overall nutrient waste compared to the monoculture of marine, halotolerant and halophilic microalgae. This paper also highlights a cultivation strategy using both mono and mixed culture over the period of increased saline condition and compares mass industrial-scale biofuel production from microalgae in three sites in Western Australia. [ABSTRACT FROM AUTHOR]

While understanding individual stakeholders' perspectives on the adoption and conversion to a biofuel-based landscape has been a subject of many previous studies on biofuels, there has been relatively little attention given to understanding how the interaction between multiple stakeholders involved in biofuel development could influence the widespread adoption of biofuel production. This paper analyzes the key stakeholder interactions utilizing various data sources including survey results, social media posts, and empirical and theoretical analyses. An intensive review is conducted for a number of surveys and research papers on different aspects of biofuel development such as land use choices, biorefinery and transportation, infrastructure development, consumer priorities, environmental impacts, etc. Following that, a stakeholder synergy approach is applied to synthesizing typical responses of stakeholders, such as producers, consumers, biorefineries, rural communities, and the government, and discussing how their responses influence each other's decisions and the overall system performance. Based on the findings of inadequate stakeholder synergy, it is recommended that new surveys and further research should be conducted to understand why synergy between stakeholders in biofuel development is absent. Additionally, this paper provides research perspectives, including (1) applying cutting-edge text-mining techniques to conduct sentiment analysis, and research and public attention analysis; (2) using an agent-based model to simulate stakeholder interactions and understand the factors that influence stakeholder synergy and the emergence of a bioeconomy. • A stakeholder synergy approach to analyzing cellulosic biofuel development in the United States. • Identified preferences, barriers, and opportunities of multiple stakeholders involved in biofuel production and consumption. • Suggested research efforts to explore and quantify stakeholder synergy for the bioeconomy. [ABSTRACT FROM AUTHOR]

Given the increasing risk of climate change and depletion of non-renewable energy sources, countries around the world have been looking into energy profile diversification whereby biomass represents one of the most appealing alternatives for energy production feedstock. To attract interest and more investment from industry players into biomass-based industries, comprehensive techno-economic analysis has to be performed. In addition, various uncertainties related to supply chain such as biomass attainability, demand variation, and material price fluctuation, have to be considered in the evaluation to yield more accurate and reliable feasibility estimation. This review paper aims to: (i) provide an overview on the different types of methods or approaches used in the feasibility evaluation of biomass-based industries from the techno-economic point of view, and (ii) outline the supply chain uncertainties that should be incorporated into the evaluation model using a Malaysian case study to illustrate the impact of these uncertainties. Apart from that, some of the unquantifiable uncertainties and risks are critically reviewed in this paper. It was found that 78 % of the reviewed articles opted for mathematical modelling evaluation method with the majority leaning towards mathematical modelling with optimization (i.e., deterministic and stochastic optimization). Furthermore, only a minority had performed stochastic evaluation that incorporates biomass supply chain uncertainties. This review discussed six quantifiable uncertainties, include: (i) biomass availability, (ii) biomass quality, (iii) transportation cost, (iv) market demand, (v) fluctuation of pricing, and (vi) wages of workers. Image 1 • Eight most popular model formulation in biomass supply chain are discussed. • Deterministic model is still the most widely used techno-economic evaluation model. • Biomass availability, quality, market demand and pricing are main uncertainties. • Biomass quality will affect both process operation and economic costing. • Stochastic model with the integration of uncertainties allow better feasibility evaluation. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) could be considered as a mature technology and nowadays it can still play a pivot role because of the urgent need to provide renewable energy sources and efficiently manage the continuously growing amount of organic waste. Biochar (BC) is an extremely versatile material, which could be produced by carbonization of organic materials, including biomass and wastes, consistently with Circular Economy principles, and "tailor-made" for specific applications. The potential BC role as additive in the control of the many well-known critical issues of AD processes has been increasingly explored over the past few years. However, a clear and comprehensive understanding of the connections between BC and AD is still missing. This review paper analyses and discusses significant references (review articles, research papers and international databases and reports), mostly published in the last 10 years. This review is aimed at addressing three key issues related to the better understanding of the BC role in AD processes: 1. Investigation of the influence of BC properties on AD performances and of their ability to counteract its main challenges; 2. Assessment of the optimal BC production chain (i.e. feedstock-pyrolysis-activation) to achieve the desired features; 3. Evaluation of the economic and environmental advantages connected to BC use in AD processes, compared to conventional solutions applied to address AD challenges. Image 1 • Biochar key properties were specific surface, pores and surface functional groups. • Lignocellulosic biomass, slow pyrolysis and physical activation made the best biochar. • Biochar addition exhibited economic and environmental advantages. • Biochar improved methane production (in average 25 %) and digestate quality. [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]

Lack of energy for powering irrigation pumps limits off-season production of rice in Malawi. This paper reviews a 10-year historical rice production data from rice farms in Karonga district in Malawi to assess the impact on rice yields and availability of straws and husks for on-site bioenergy production in small scale gasifiers, to power irrigation pumping during off season over a projected period of 15 years. Annual production of rice straw and husks has been estimated using residues to product ratio while taking into account collectable amounts and allocations to competing uses. The heating values obtained from literature and validated by analytical Gross Calorific Values of straws and husks have been used to estimate the bioenergy potential. Irrigation pump capacity and pumping rate calculated from daily water demand, and carbon emissions savings determined from the differences between emissions generated by fossil diesel and bioenergy powered irrigation have been used for calculating environmental benefits. The sales of excess rice provided estimates for financial gains. In the base year, generation of straws and husks of about 44117 and 6703 t and collectable portions of 40% and 65%, respectively, are estimated, providing a total bioenergy potential of 16.64 GWh. With onsite-generated bioenergy, irrigated land can increase from 2367 to 13362 ha while rice and bioenergy production increases from 34703 to 59970 t and 15.34–87.72 GWh, respectively, by the 10th cycle. Cumulative revenue of US$354.60 million from sales of excess rice and net carbon emissions saving of 285.33 kilotonnes can be achieved by using electricity generated for irrigation pumping. Investment costs in electricity generation can breakeven by 8th year if sold at US0.166/kWh. Therefore, on-site generated bioenergy targeting irrigation pumping for off-season rice production is an enabler for promoting positive and sustainable fuel /food nexus in rice farming communities through intensive farming. [ABSTRACT FROM AUTHOR]

Economic and environmental developments in the last decades call for the displacement of fossil fuels to alternative energy sources. Biofuels are considered as a part of the solution for this challenge. Sustainable raw materials for the production of transportation biofuels such as biodiesel, biobutanol and bioethanol, can be obtained from algal biomass. In particular, marine macroalgal biomass is a promising feedstock for transportation biofuels because of (the) its fast growth and its potential cultivation on seawater, avoiding competition of resources with conventional agriculture of terrestrial plants used for food. In addition, dissolved inorganic nutrients like nitrogen, phosphorous and carbon are taken up by macroalgae, helping to alleviate eutrophication in seas and oceans. Using biological, chemical and engineering advances in the last decades, technologies to provide cost efficient cultivation, harvesting, extraction and processing of sustainable biofuels have to be elaborated. This paper provides a review of macroalgae based biorefineries with offshore cultivation and consequent biomass conversion into transportation liquid biofuels. We discuss the methods for offshore cultivation, harvesting, and conversion of macroalgae biomass into liquid transportation biofuels. Based on the current information and global experience, we present local perspectives specific for France, Germany, Norway, the Netherlands and Israel on the potential use of Exclusive Economic Zone for transportation biofuels production. Marketable suggestions for future research need to include all stakeholders of a given site for offshore biorefinery development. [ABSTRACT FROM AUTHOR]

Owing to its important potential, bioenergy has been integrated in the recent ambitious renewable energy program of Algeria. As biomass sources are tremendous and so diversified, bioenergy production can take many and varied forms. Assessment of national biomass potential is essential for the development of bioenergy sector in Algeria. This paper focuses on identifying domestic sustainable biomass resources with emphasis on energy production. The energy potential of waste generated by different sectors (urban, industrial …) is investigated. The resulted outcome showed that urban waste are the prominent fermentable resource and can produce as much as 1685 GWh through the anaerobic digestion process. Other agribusiness resources, although at lower extent, can also contribute to the global bioenergy potential in Algeria. The estimated energy capable to be generated from the investigated biomass resources can cover the annual consumption of more than one million inhabitants. [ABSTRACT FROM AUTHOR]

Economically feasible production of conventional bioenergies such as biofuels, biopower and bioheat is a challenge in biorefineries because they have to compete with inexpensive fossil fuel energies while external production costs are rarely included into the present-day policies. Biomass consists of unique complex chemical structures that cannot be easily artificially synthesized and may be beneficially employed in various practical applications. Therefore, strategies relying on complete biomass disintegration through combustion, gasification or fermentation only to simple usable bioenergies do not lead to optimal utilization of biomass feedstock. Instead, cascading approaches are required in order to maximize biomass valorization. Consequently, high-value low-volume bioproducts coupled to bioenergies with potential to improve economic viability of biorefineries and biomass resource utilization are urgently required. Integrated production of bioenergies and bioproducts may be achieved by coupling existing biofuel plants with new bioindustries, by retrofitting existing bioindustries with new bioenergy facilities or by erecting completely new integrated facilities. The current paper reviews literature and provides systematized insights into various high-value low-volume bioproducts coupled to bioenergies in biorefinery contexts. It analyses potential benefits of a range of such bioproducts and gives comments on associated business development. The review thus creates foundations for more thoughtful design procedures of economically feasible sustainable biorefineries that could meet technical and market requirements and improve cascading biomass utilization. Owing to insufficient technology readiness the study also aims at improved understanding of major technological gaps limiting expanded economically viable utilization of high-value bioproducts through biorefineries. It is emphasized that the major advantage of biorefineries is their suitability for maximizing valorization of structural and energetic potentials lying in biomass. The study suggests that new business models introducing high-value bioproducts to biorefineries are essential for achieving economic viability of industries within bioeconomy. [ABSTRACT FROM AUTHOR]

This paper reviews European land and bioenergy potential studies to 1) identify shortcomings related to how they account for agricultural intensification and its associated environmental effects, and sustainability constraints, and 2) provide suggestions on how these shortcomings can be improved in future assessments. The key shortcomings are: The environmental impacts of intensification are nearly always ignored in the reviewed studies, while these impacts should be accounted for if intensification is required to make land available for energy cropping. Future productivity developments of crops and livestock, and the associated land-use and environmental effects are currently limited to conventional intensification measures whereby the proportion between inputs and outputs is fixed. Sustainable intensification measures, which increase land productivity with similar or lower inputs, are ignored in the reviewed studies. Livestock productivity developments, livestock specific intensification measures and their environmental effects are poorly or not at all covered in the reviewed studies. Most studies neglect sustainability constraints other than GHG emissions in the selection of energy crops. This includes limitations to rainfed energy crop cultivation, a minimum number of crop species, the structural diversity within cropping areas and the integration of energy crops in existing or new crop rotations, while simultaneously considering the effects on subsequent crops. These shortcomings suggest that the identification of sustainable pathways for European bioenergy production requires a more integrative approach combining land demand for food, feed and energy crop production, including different intensification pathways, and the consequent direct and indirect environmental impacts. A better inclusion of management practices into such approach will improve the assessment of intensification, its environmental consequences and the sustainable bioenergy potential from agricultural feedstocks. [ABSTRACT FROM AUTHOR]

Recent interest in biomass supply chain management has stimulated research efforts in the industry and academic communities. Techno-economic modeling and optimization efforts targeted on the upstream segment of the forest biomass to bio-oil supply chain are reviewed. Key components of upstream supply chain decision making are then presented through an overview and classification of the existing methods and contributions. There is a need to classify and analyze the relevant methodologies and approaches identified in prior studies, and to subsequently assess their usefulness through empirical research and case-based analysis. Both narrative and systematic literature reviews are performed using qualitative analysis and classic bibliometric techniques to demonstrate the scope of current papers and the call for future needs. It is found, due to growing demands for bioenergy, future biomass-to-bioenergy supply chains should draw upon existing research toward the development of efficient and effective forest biomass supply chain networks. It is further concluded that a new generation of pretreatment technologies is needed for techno-economic optimization of upstream forest biomass value chains. [ABSTRACT FROM AUTHOR]

Sustainable economic development and renewable energy carriers are challenges facing hub cities that will influence their future role in trade and transport. The objective of this paper is to discuss the interactions between alternative transport fuels for international applications and Singapore’s energy system as a central hub of global transport. The process chains for the supply of conventional fuels, liquefied natural gas, biofuels, and liquid hydrogen in Singapore are analysed by applying a well-to-tank analysis, following which the energy demand and the associated greenhouse gas emissions are calculated. A sensitivity analysis is performed to assess the individual impacts of various processes. A comparison of process chains for the supply of fuels for marine and aviation purposes shows that conventional energy carriers and liquefied natural gas achieve higher energy efficiencies than biofuels and liquid hydrogen. Alternative fuels reduce greenhouse gas emissions by varying degrees depending on the fuel type. An analysis of interactions with Singapore’s energy system identifies emerging opportunities and challenges for the city-state’s economic system associated with future development of international transport. Although alternative fuels offer the possibility of diversifying Singapore’s energy supply, creating new business opportunities, and increasing Singapore’s impact on fighting climate change, limited resource potentials and higher energy prices set new challenges to secure Singapore’s role as an international trade and transport hub. [ABSTRACT FROM AUTHOR]

In Brazil, bioelectricity generation from sugarcane bagasse and black liquor is regarded as a sustainable electricity supply option. However, questions regarding land use, investment decisions, and demand for paper, ethanol and sugar make its future role uncertain. The aim of this paper is to present a novel modelling framework based on a soft-link between a multi-sectoral Brazilian integrated assessment model (MUSE-Brazil) and an electricity portfolio optimisation model (EPOM). The proposed framework is capable of dynamically simulating sectoral electricity demand, regional bioenergy production under land use constraints and optimal power sector technological shares in each of the electricity subsystems. Considering Brazil under a 2 °C carbon budget, two scenarios based on economic attractiveness of producing second-generation ethanol have been investigated. Under the scenario where second-generation ethanol is not produced, outputs indicate that by 2050, Brazil would increase sugarcane and wood production by 68% and 49% respectively without causing direct or indirect deforestation. Agriculture intensification is evidenced as an alternative for reducing land use disruptions. Bioelectricity share is projected to remain around 9–10%. However, if second generation ethanol becomes cost-effective, thus limiting bagasse availability, the share of bioelectricity production would decrease to approximately 7.7%, with natural gas-fired plants playing a stronger role in the future power system expansion, causing an increase on electricity sector emissions. • A novel framework considering energy systems and portfolio optimisation is proposed. • Two different carbon constrained bioelectricity scenarios in Brazil are investigated. • Power system emissions could represent between 13.3% and 14.5% of the carbon budget. • Controlling deforestation in the Amazon is fundamental to reach mitigation targets. • Bioelectricity potential is considerably reduced when 2G ethanol is produced. [ABSTRACT FROM AUTHOR]