Towards integrated sustainability assessment for energetic use of biomass: A state of the art evaluation of assessment tools

Biomass is expected to play an increasingly significant role in the ‘greening’ of energy supply. Nevertheless, concerns are rising about the sustainability of large-scale energy crop production. Impacts must be assessed carefully before deciding whether and how this industry should be developed, and what technologies, policies and investment strategies should be pursued. There is need for a comprehensive and reliable sustainability assessment tool to evaluate the environmental, social and economic performance of biomass energy production. This paper paves the way for such a tool by analysing and comparing the performance and applicability of a selection of existing tools that are potentially useful for sustainability assessment of bioenergy systems. The selected tools are: Criteria And Indicators (C&I), Life Cycle Assessment (LCA), Environmental Impact Assessment (EIA), Cost Benefit Analysis (CBA), Exergy Analysis (EA) and System Perturbation Analysis (SPA). To evaluate the tools, a framework was constructed that consists of four evaluation levels: sustainability issues, tool attributes, model structure, area of application. The tools were then evaluated using literature data and with the help of a Delphi panel of experts. Finally, a statistical analysis was performed on the resulting data matrix to detect significant differences between tools. It becomes clear that none of the selected tools is able to perform a comprehensive sustainability assessment of bioenergy systems. Every tool has its particular advantages and disadvantages, which means that trade-offs are inevitable and a balance must be found between scientific accuracy and pragmatic decision making. A good definition of the assessment objective is therefore crucial. It seems an interesting option to create a toolbox that combines procedural parts of C&I and EIA, supplemented with calculation algorithms of LCA and CBA for respectively environmental and economic sustainability indicators. Nevertheless, this would require a more comprehensive interdisciplinary approach to align the different tool characteristics and focuses.     

Growing trade of bioenergy in the EU: Public acceptability, policy harmonization, European standards and certification needs

Since 2000, the consumption of bioenergy in the European Union has grown, along with a concurrent growth in the trade of biomass for energy purposes (though traded volumes still remain small). Bioenergy production and trade will likely continue to increase into the future, driven by climate change concerns, emissions reduction targets, increasing concerns about domestic energy security and favourable policies. The harmonization of European standards and the development of certification systems are key issues to resolving potential negative effects of increased biomass trade. Certification systems not only address the issue of environmental sustainability from production to end-use, but also allow for product differentiation while adding value to sustainably produced products, which can ultimately enhance a competitive and sustainable bioenergy market. In addition to analyzing bioenergy trade growth in the European Union, a questionnaire survey of 92 bioenergy experts from eight member states within the European Union was conducted. Survey results show that bioenergy is highly accepted in the European Union but that there is a lack of European standards and policy harmonization, along with the absence of a competitive market or a certification system, all of which are necessary for sustainable production and trade of bioenergy. A large majority (63 percent) of the total respondents agreed that the certification of bioenergy is necessary to promote the sustainable use of biomass.     

Assessing the environmental performance and sustainability of bioenergy production in Sweden: A life cycle assessment perspective

Bioenergy is one of the most dynamic and rapidly changing sectors of the global energy economy. The use of food crops for conversion to biofuel has been criticized for several reasons, among which its competition with the global food chain. Instead, lignocellulosic substrates are claimed to provide a bioenergy alternative without competing with food demand. This is particularly true when dealing with residues or waste. In this paper, we explored the environmental performance and sustainability of a bioenergy production system that integrates wastewater treatment, willow farming, and a Combined Heat and Power plant (CHP) located in Enköping (Sweden). Several methodologies for environmental assessment are integrated in this study within a life cycle perspective to investigate material and energy requirements as well as emissions and related impacts of the whole bioenergy production chain. Results show that full integration of different subsystems of a productive network is a desirable option for bioenergy production, within a zero emission oriented production pattern. The investigated wood biomass powered CHP plant was able to co-generate heat and electricity with high production efficiency and much better environmental performance and sustainability than fossil fuel based power plants.     

Environmental factors in woodfuel production: Opportunities,risks, and criteria and indicators for sustainable practices

Bioenergy from sustainably managed forest ecosystems could provide a renewable, carbon-neutral source of energy in many nations and communities throughout the world. In order for forest bioenergy to be an ecologically sustainable fuel source, woodfuel procurement systems must not adversely impact forest ecosystems or the environment. Sustainable forest management (SFM) certification schemes are one mechanism for applying standards and monitoring regimes to forest management systems to ensure ecological sustainability. This paper provides a global review of the main environmental risks to forest ecosystems that can arise from household- to industrial-scale woodfuel production systems, including forest soil quality and site productivity, water resources, biodiversity and carbon budgets. A set of regionally adaptable principles, criteria, indicators and verifiers of sustainable forest management were developed, based on criteria and indicators from existing internationally recognized certification frameworks and scientific literature and tailored to address issues relevant to producing and harvesting forest bioenergy feedstocks. A variable monitoring approach and a three-tiered certification approach are proposed as two methods for enabling the adoption of certification and associated monitoring requirements across a wide range of forest operations in regions with widely differing levels of development. The importance of the Adaptive Forest Management framework inherent in certification systems to ensuring the efficacy and continual improvement in woodfuel sustainability is stressed. The proposed principles, criteria, indicators and verifiers can be adapted to local conditions and incorporated into existing sustainable forest management and green energy certification schemes, as well as other criteria and indicator frameworks, to ensure the environmental sustainability of woodfuel production systems.     

A participatory systems approach to modeling social, economic, and ecological components of bioenergy

Availability of and access to useful energy is a crucial factor for maintaining and improving human well-being. Looming scarcities and increasing awareness of environmental, economic, and social impacts of conventional sources of non-renewable energy have focused attention on renewable energy sources, including biomass.

The complex interactions of social, economic, and ecological factors among the bioenergy system components of feedstock supply, conversion technology, and energy allocation have been a major obstacle to the broader development of bioenergy systems. For widespread implementation of bioenergy to occur there is a need for an integrated approach to model the social, economic, and ecological interactions associated with bioenergy. Such models can serve as a planning and evaluation tool to help decide when, where, and how bioenergy systems can contribute to development.

One approach to integrated modeling is by assessing the sustainability of a bioenergy system. The evolving nature of sustainability can be described by an adaptive systems approach using general systems principles. Discussing these principles reveals that participation of stakeholders in all components of a bioenergy system is a crucial factor for sustainability.

Multi-criteria analysis (MCA) is an effective tool to implement this approach. This approach would enable decision-makers to evaluate bioenergy systems for sustainability in a participatory, transparent, timely, and informed manner.     

The role of hydrogen and fuel cells to store renewable energy in the future energy network – potentials and challenges

The penetration of renewable energy sources is expected to rapidly increase from 15% to 50% in 2050 due to their vital contribution to the global energy requirements, sustainability and quality of life in economical, environmental and health aspects. This huge rise highlights the necessity of development of energy storage systems, especially for intermittency renewable energies such as solar photovoltaic and wind turbine, in order to balance the energy network. In this study, renewable energy options including pumped hydro, pressurized air, flywheels, Li ion batteries, hydrogen and super-capacitors are compared based on a specific set of criteria. The criteria considered are energy/power density, ease of integration with the existing energy network, cost effectiveness, durability, efficiency and safety. Our study showed that storing renewable energy sources in the form of hydrogen through the electrolysis process is ranked as the most promising option considering the mentioned criteria. It brings about several benefits suggesting that hydrogen and fuel cells are promising contributors towards a more sustainable future, both in energy demand and environmental sustainability.     

Striving to further harmonization of sustainability criteria for bioenergy in Europe: Recommendations from a stakeholder questionnaire

This questionnaire analyzed the ongoing development of sustainability criteria for solid and liquid bioenergy in the European Union and further actions needed to come to a harmonization of certification systems, based on EU stakeholder views. The questionnaire, online from February to August 2009, received 473 responses collected from 25 EU member countries and 9 non-European countries; 285 could be used for further processing. A large majority of all stakeholders (81%) indicated that a harmonized certification system for biomass and bioenergy is needed, albeit some limitations. Amongst them, there is agreement that (i) a criterion on ‘minimization of GHG emissions’ should be included in a certification system for biomass and bioenergy, (ii) criteria on optimization of energy and on water conservation are considered of high relevance, (iii) the large variety of geographical areas, crops, residues, production processes and end-uses limits development towards a harmonized certification system for sustainable biomass and bioenergy in Europe, (iv) making better use of existing certification systems and standards improves further development of a harmonized European biomass and bioenergy sustainability certification system and (v) it is important to link a European certification system to international declarations and to expand such a system to other world regions.     

Sustainable bioenergy for India: Technical,economic and policy analysis

India's energy challenges are multi-pronged. They are manifested through growing demand for modern energy carriers, a fossil fuel dominated energy system facing a severe resource crunch, the need for creating access to quality energy for the large section of deprived population, vulnerable energy security, local and global pollution regimes and the need for sustaining economic development. Renewable energy is considered as one of the most promising alternatives. Recognizing this potential, India has been implementing one of the largest renewable energy programmes in the world. Among the renewable energy technologies, bioenergy has a large diverse portfolio including efficient biomass stoves, biogas, biomass combustion and gasification and process heat and liquid fuels. India has also formulated and implemented a number of innovative policies and programmes to promote bioenergy technologies. However, according to some preliminary studies, the success rate is marginal compared to the potential available. This limited success is a clear indicator of the need for a serious reassessment of the bioenergy programme. Further, a realization of the need for adopting a sustainable energy path to address the above challenges will be the guiding force in this reassessment. In this paper an attempt is made to consider the potential of bioenergy to meet the rural energy needs: (1) biomass combustion and gasification for electricity; (2) biomethanation for cooking energy (gas) and electricity; and (3) efficient wood-burning devices for cooking. The paper focuses on analysing the effectiveness of bioenergy in creating this rural energy access and its sustainability in the long run through assessing: the demand for bioenergy and potential that could be created; technologies, status of commercialization and technology transfer and dissemination in India; economic and environmental performance and impacts; bioenergy policies, regulatory measures and barrier analysis. The whole assessment aims at presenting bioenergy as an integral part of a sustainable energy strategy for India. The results show that bioenergy technology (BET) alternatives compare favourably with the conventional ones. The cost comparisons show that the unit costs of BET alternatives are in the range of 15–187% of the conventional alternatives. The climate change benefits in terms of carbon emission reductions are to the tune of 110 T C per year provided the available potential of BETs are utilized.     

Trends in bioconversion of lignocellulose: Biofuels,platform chemicals & biorefinery concept

Bioconversion of renewable lignocellulosic biomass to biofuel and value added products are globally gaining significant prominence. Market forces demonstrate a drive towards products benign to natural environment increasing the importance of renewable materials. The development of second generation bioethanol from lignocellulosic biomass serves many advantages from both energy and environmental point of views. Biomass an inexpensive feedstock considered sustainable and renewable, is an option with the potential to replace a wide diversity of fossil based products within the energy sector; heat, power, fuels, materials and chemicals. Lignocellulose is a major structural component of woody and non-woody plants and consists of cellulose, hemicellulose and lignin. The effective utilization of all the three components would play a significant role in the economic viability of cellulosic ethanol. Biomass conversion process involves five major steps, choice of suitable biomass, effective pretreatment, production of saccharolytic enzymes-cellulases and hemicellulases, fermentation of hexoses and pentoses and downstream processing. Within the context of production of fuels from biomass, pretreatment has come to denote processes by which cellulosic biomass is made amenable to the action of hydrolytic enzymes. The limited effectiveness of current enzymatic process on lignocellulose is thought to be due to the relative difficulties in pretreating the feedstocks. The present review is a comprehensive state of the art describing the advancement in recent pretreaments, metabolic engineering approaches with special emphasis on the latest developments in consolidated biomass processing, current global scenario of bioethanol pilot plants and biorefinery concept for the production of biofuels and bioproducts.     

Review on fermentative biohydrogen production from water hyacinth,wheat straw and rice straw with focus on recent perspectives

Hydrogen (H₂) is often considered as the best option to store energy coming from renewable sources. Hydrogen production from lignocellulosic biomass via fermentation offers low cost and environmental friendly method in terms of energy balance and provides a sustainable pathway for utilization of huge amount of unused biomass. In this regard, special attention on potential of different lignocellulosic biomass is required. In this paper, the fermentative hydrogen production from three carbohydrates-rich biomass: water hyacinth, wheat straw and rice straw is comprehensively reviewed. In other point of view, usage of H₂ has a 10% growth annually that will reach to 8–10% of total energy in 2025. Furthermore, research on recent trends of fermentative hydrogen production is crucial and vital. However, the majority of the published researches in the last decade confirmed that some challenges exists which are the process optimization, effecting parameters and commercialization aspects.     

Life cycle analysis for future photovoltaic systems using hybrid solar cells

Global climate change concerns have lead to growing demand for renewable energy sources (RES). However the viability of these sources is critically dependent on environmental, economic and technological considerations. This paper focuses on the environmental aspect of future photovoltaic (PV) systems which are assessed through life cycle analysis (LCA). Previous LCA studies on commercially available PV systems are reviewed. The sustainable evaluation methods used in these studies are also discussed. These methods are applied to the hybrid quantum dot (QD)-based solar cells currently under development within a project between the University of Manchester and Imperial College London. The aim of this project is to develop affordable solar cells with efficiencies up to 10% for micro-generation applications. Presently hybrid QD-based solar cells are not commercially fabricated; therefore the study is mostly based on very small laboratory-scale production. For easy comparability 10% conversion efficiency and 25 years lifetime are initially assumed. Lower conversion efficiencies and shorter lifetimes likely to initially characterise emerging PV technologies such as the hybrid QD-based solar cells are discussed. Comparable criteria for sustainability of electricity-generating systems namely net energy ratio (NER), energy pay-back time (EPB-T) and CO₂ emissions per unit generated during lifetime are found to be lower than current commercially available PV modules.     

Direct and indirect land use changes issues in European sustainability initiatives: State-of-the-art, open issues and future developments

Facing climate change and growing energy prices, the use of bioenergy is continuously increasing in order to diminish greenhouse gas emissions, secure energy supply and create employment in rural areas. Because the production of biomass or biofuels, wherever it takes place, comes along with externalities, positive or negative, the need for biomass and bioenergy sustainability criteria is more than ever felt. Research on sustainability criteria and certification systems has started through several national and international initiatives. Considering the benefits of an increased use of bioenergy but also the urge for limiting potential negative environmental and socio-economic impacts, the aim of these initiatives was to make the first move regarding bioenergy sustainability, while waiting for the European legislation to regulate this crucial issue. Land use changes, whether direct or indirect, are one of the most important consequences of bioenergy production. While direct land use changes are more easily assessed locally, indirect land use changes exceed the company level and need to be considered at a global scale. Methodologies for dealing with direct and indirect land use changes are proposed among others in the European, Dutch, British and German sustainability initiatives. This paper aims at presenting and comparing those four European initiatives, with a focus on their propositions for direct and indirect land use changes assessment. Key issues are discussed and recommendations are made for steps to overcome identified difficulties in accurately assessing the effects of indirect land use change due to bioenergy production.     

Modelling sustainable bioenergy potentials from agriculture for Germany and Eastern European countries

This paper presents a model for analyzing the sustainable potential of agricultural biomass for energy production. Available land and residue potentials are assessed up to 2030 for Germany, Poland, the Czech Republic and Hungary. Two scenarios are presented: a “business as usual” scenario is compared to a sustainability scenario. The latter implements a comprehensive sustainability strategy, taking also into account non-agricultural land use such as building activity and nature conservation. On the one hand our model quantifies the conflict of objectives between enhanced extensification in agriculture and increased area for nature conservation. On the other hand the synergies in restricting built up area and increased mobilisation of agricultural residues are assessed. Additionally the impact of reduced subsidized agricultural exports from the EU is calculated, also as an indicator for the influence of world food markets on bioenergy potentials.Our results show that the sustainable energy potential from agricultural biomass is strongly restricted for Germany and the Czech Republic compared to their energy demand. But in Poland and Hungary native agricultural biomass provides a much higher potential for energy supply, even if sustainability is comprehensively considered. However, this is strongly influenced by the amount of agricultural exports of each country. For bioenergy from agricultural cultivation to remain a sustainable option in the energy sector, its influence on the food markets must be respected more thoroughly and a comprehensive approach to sustainable development in land use is a prerequisite.     

Developing a sustainability framework for the assessment of bioenergy systems

The potential for biomass to contribute to energy supply in a low-carbon economy is well recognised. However, for the sector to contribute fully to sustainable development in the UK, specific exploitation routes must meet the three sets of criteria usually recognised as representing the tests for sustainability: economic viability in the market and fiscal framework within which the supply chain operates; environmental performance, including, but not limited to, low carbon dioxide emissions over the complete fuel cycle; and social acceptability, with the benefits of using biomass recognised as outweighing any negative social impacts. This paper describes an approach to developing a methodology to establish a sustainability framework for the assessment of bioenergy systems to provide practical advice for policy makers, planners and the bioenergy industry, and thus to support policy development and bioenergy deployment at different scales. The approach uses multi-criteria decision analysis (MCDA) and decision-conferencing, to explore how such a process is able to integrate and reconcile the interests and concerns of diverse stakeholder groups.     

Indicators of bioenergy-related certification schemes – An analysis of the quality and comprehensiveness for assessing local/regional environmental impacts

Bioenergy is receiving increasing attention because it may reduce greenhouse gas emissions, secure and diversify energy supplies and stimulate rural development. The environmental sustainability of bioenergy production systems is often determined through life-cycle assessments that focus on global environmental effects, such as the emission of greenhouse gases or air pollutants. Local/regional environmental impacts, e.g., the impacts on soil or on biodiversity, require site-specific and flexible options for the assessment of environmental sustainability, such as the criteria and indicators used in bioenergy certification schemes.In this study, we compared certification schemes and assessed the indicator quality through the environmental impact categories, using a standardized rating scale to evaluate the indicators. Current certification schemes have limitations in their representation of the environmental systems affected by feedstock production. For example, these schemes predominantly use feasible causal indicators, instead of more reliable but less feasible effect indicators. Furthermore, the comprehensiveness of the depicted environmental systems and the causal links between human land use activities and biophysical processes in these systems have been assessed. Bioenergy certification schemes seem to demonstrate compliance with underlying legislation, such as the EU Renewable Energy Directive, rather than ensure environmental sustainability. Beyond, certification schemes often lack a methodology or thresholds for sustainable biomass use. Lacking thresholds, imprecise causal links and incomplete indicator sets may hamper comparisons of the environmental performances of different feedstocks. To enhance existing certification schemes, we propose combining the strengths of several certification schemes with research-based indicators, to increase the reliability of environmental assessments.     

Sustainable use of eucalypt biomass grown on short rotation coppice for bioenergy

Bioenergy is one of the alternatives to reduce the dependence of global energy on fossil fuels. The short rotation coppice (SRC) of eucalypt species appears as an interesting option for forest biomass production in a short time. However, the harvesting of whole trees (included the crown) in SRC systems has implications on sustainable land use. More information is required on the increase of biomass as renewable energy resource to achieve the sustainability of these crops. The main objective of this research was to evaluate the sustainable use of biomass from very high-density eucalypt plantations, managed at tropical conditions for bioenergy. To accomplish this objective, the tree was fractionated into three fractions: stem, branches, and leaves, and there was determination of the dry matter, energy yield, and nutrients export. This experiment used a short rotation coppice, a hybrid clone of Eucalyptus urophylla × Eucalyptus grandis, of 2 years old. According to the results obtained, the density planting and fertilization levels have a greater influence on the dry matter yield, energy yield, and nutrient exports. The higher density planting reaches mean values of 30.9 tonnes of dry matter per hectare (t DM ha⁻¹) and 743.3 GJ ha⁻¹. Considering the biomass yield and nutrients export of short rotation coppice of eucalypt, the higher density planting with the lower dose of fertilization is more indicative of sustainable use. The leaves have an important participation in nutrients export and should be retained in the soil of forest.     

A review on clean energy solutions for better sustainability

This paper focuses on clean energy solutions in order to achieve better sustainability, and hence discusses opportunities and challenges from various dimensions, including social, economic, energetic and environmental aspects. It also evaluates the current and potential states and applications of possible clean‐energy systems. In the first part of this study, renewable and nuclear energy sources are comparatively assessed and ranked based on their outputs. By ranking energy sources based on technical, economic, and environmental performance criteria, it is aimed to identify the improvement potential for each option considered. The results show that in power generation, nuclear has the highest (7.06/10) and solar photovoltaic (PV) has the lowest (2.30/10). When nonair pollution criteria, such as land use, water contamination, and waste issues are considered, the power generation ranking changes, and geothermal has the best (7.23/10) and biomass has the lowest performance (3.72/10). When heating and cooling modes are considered as useful outputs, geothermal and biomass have approximately the same technical, environmental, and cost performances (as 4.9/10), and solar has the lowest ranking (2/10). Among hydrogen production energy sources, nuclear gives the highest (6.5/10) and biomass provides the lowest (3.6/10) in ranking. In the second part of the present study, multigeneration systems are introduced, and their potential benefits are discussed along with the recent studies in the literature. It is shown that numerous advantages are offered by renewable energy‐based integrated systems with multiple outputs, especially in reducing overall energy demand, system cost and emissions while significantly improving overall efficiencies and hence output generation rates. Copyright © 2015 John Wiley & Sons, Ltd.     

Integrated assessment of bioelectricity technology options

Power generation from biomass is a sustainable energy technology which can contribute to substantial reductions in greenhouse gas emissions, but with greater potential for environmental, economic and social impacts than most other renewable energy technologies. It is important therefore in assessing bioenergy systems to take account of not only technical, but also environmental, economic and social parameters on a common basis. This work addresses the challenge of analysing, quantifying and comparing these factors for bioenergy power generation systems. A life-cycle approach is used to analyse the technical, environmental, economic and social impacts of entire bioelectricity systems, with a number of life-cycle indicators as outputs to facilitate cross-comparison. The results show that similar greenhouse gas savings are achieved with the wide variety of technologies and scales studied, but land-use efficiency of greenhouse gas savings and specific airborne emissions varied substantially. Also, while specific investment costs and electricity costs vary substantially from one system to another the number of jobs created per unit of electricity delivered remains roughly constant. Recorded views of stakeholders illustrate that diverging priorities exist for different stakeholder groups and this will influence appropriate choice of bioenergy systems for different applications.     

Sustainable ethanol production from lignocellulosic biomass - Application of exergy analysis

The sustainability of the second-generation biofuels requests to confirm that the energy produced from lignocellulosic biomass is significantly greater than the energy consumed in the process. As lignocellulosic biomass does not affect the food supply, sugarcane bagasse was analyzed as a raw material for second-generation biofuels production. Exergy analysis serves as a unified and effective tool to evaluate the global process efficiency. Exergy analysis evaluates the performance of sugarcane bagasse and its sustainability in the bioethanol production process. In this work, four ethanol production topologies using the typical daily amount of residual biomass produced by the sugar industry were compared. The exergy analysis concept is effective in screening design alternatives with the lowest environmental impact for second-generation bioethanol fuel production from renewable resources. This study was executed by the use of the Aspen Plus^® program and other software developed by the authors.     

A new approach for evaluation of renewable energy resources: A case of Turkey

The energy needs of Turkey, especially electricity and heating, will eventually increase in the next years since Turkey is one of the developing countries. The current energy policy of Turkey is mainly based on the fossil fuels and natural gases. However, the fossil fuels and natural gas are extremely harmful energy resources for environment as the emissions of greenhouse gases are very high level. Therefore, a long-term renewable energy policy planning should be developed. In this study, the evaluation of renewable energy resources for Turkey is accomplished using intuitionistic fuzzy Visekriterijumsko Kompromisno Rangiranje method in which criteria are expressed in both a quantitative and qualitative way for the first time in the literature. In the evaluation process, wind, hydro, solar, geothermal, and biomass are evaluated. Four main criteria – technological, environmental, sociological, and economic – are considered as main evaluation criteria and totally 12 subcriteria related to main criteria are also taken into consideration. Moreover, the sensitivity analysis has been conducted to identify which renewable energy resource is a better option under different circumstances.