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In this study, the effect of recycling the non-condensable gases (NCG) in the catalytic pyrolysis of hybrid poplar using FCC catalyst was investigated. A 50mm bench scale fluidized bed reactor at 475°C with a weight hourly space velocity (WHSV) of 2h(-1) and a gas recycling capability was used for the studies. Model fluidizing gas mixtures of CO/N(2), CO(2)/N(2), CO/CO(2)/N(2) and H(2)/N(2) were used to determine their independent effects. Recycling of the NCG in the process was found to potentially increase the liquid yield and decrease char/coke yield. The model fluidizing gases increased the liquid yield and the CO(2)/N(2) fluidizing gas had the lowest char/coke yield. The (13)C-NMR analysis showed that recycling of NCG increases the aromatic fractions and decreases the methoxy, carboxylic and sugar fractions. Recycling of NCG increased the higher heating value and the pH of the bio-oil as well as decreased the viscosity and density.

Abstract Over the last decades, electricity markets across OECD countries have been subjected to profound structural changes with far-reaching implications on the economy and the environment. This paper investigates the effect of restructuring – changes in entry regulations, the degree of vertical integration and ownership structure – on GHG emissions. The findings show that competition policies – particularly reducing the degree of vertical integration and increasing privatization – correlate negatively with emission intensity. However, the environmental effect of reducing market entry barriers is generally insignificant. Integration of competition and stringent environmental policies are required to reduce GHG emissions and improve environmental quality.

Although the integrated energy and environmental planning processes of cities and territories with more than 50,000 inhabitants differ, previous studies suggest that long-term, model-based energy planning processes have a common scheme that can also be used as a framework for reviewing the methods and the tools that are used in the integrated energy planning of these cities and territories. This paper first presents a generic integrated energy planning procedure in which the planning activities are divided into four main phases. Second, the methods and the tools that are used for these diverse planning tasks are mapped to the suggested generic planning procedure tasks. Finally, the combined use of these methods and tools in the scope of integrated energy planning are briefly discussed from a mapping point of view.

Pyrolysis of the waste organic fraction is expected to be a central element to meet the primary energy demand in future: it increases the impact of renewable energy sources on the power generation sector and allows the amount of waste to be reduced, putting an end to landfills. In the present study, kinetic studies on the pyrolysis of biomass wastes are carried out. Two kinds of industrial organic waste are investigated: brewery spent grain (BSG) and medium-density fiberboard (MDF). The main target of this work is to provide a global equation for the one-step pyrolysis reaction of the investigated materials in an argon atmosphere using isoconversional methods. The conducted analysis allowed to estimate the activation energy as 225.4-253.6 kJ/mol for BSG and 197.9-216.7 kJ/mol for MDF. For both materials nth order reaction was proposed with reaction order of 7.69-8.70 for BSG and 6.32-6.55 for MDF. The developed equation allowed to simulate the theoretical curves of thermal conversion. These curves indicated the highest conversion at the temperature of the degradation of dominant component, which was experimentally verified. By this method, a one-step kinetic model is derived, which can be applied for the reaction kinetics in the CFD modelling of, e.g., pyrolysis and gasification processes.

AbstractIn photovoltaic (PV) projects, it is important to establish a common practice for professional risk assessment, which serves to reduce the risks associated with related investments. The objective of this paper is to present a methodology on how to improve the current understanding of several key aspects of technical risk management during the PV project lifecycle, with the identification of technical risks and their economic impact. To achieve this, available statistical data of failures during a PV project have been collected with the aim to (i) suggest a guideline for the categorisation of failure and (ii) develop a methodology for the assessment of the economic impact of failures occurring during operation but which might have originated in previous phases. The risk analysis has the aim to assess the economic impact of technical risks and how this can influence various business models and the levelised cost of electricity. This paper presents the first attempt to implement cost‐based failure modes and effects analysis to the PV sector and to define a methodology for the estimation of economic losses because of planning failures, system downtime and substitution/repair of components. The methodology is based on statistical analysis and can be applied to a single PV plant or to a large portfolio of PV plants in the same market segment. The quality of the analysis depends on the amount of failure data available and on the assumptions taken for the calculation of a cost priority number. The overall results can be linked to the cost of periodic and corrective maintenance and form the basis to estimate the impact of various risk and mitigation scenarios in PV business models. Copyright © 2017 John Wiley & Sons, Ltd.

Abstract Heat pump systems (HPS) are a promising technology to reduce greenhouse gas emissions in the building sector by low-emission heat supply. However, their market penetration is inhibited by lower costs of conventional technologies. Thus, heat pumps must become cheaper to purchase and operate. Investment costs are related to the design, while operating costs are related to operational efficiency. Although design and operation are mutually interdependent, they are considered separately in conventional design procedures. This disconnect prevents the full potential of the technology from being realized. In this contribution, we present a framework to simultaneously consider design and operation in one optimization step using a simulation-based optimization approach called HPS eOD Design. Based on a building heat demand, the framework optimizes annualized costs and emissions of heat pump systems considering the operational behaviour already in the design. By coupling the optimization program with a software for automatic generation of building models called TEASER, HPS eOD Design can be applied to a wide variety of building types and locations. Optimization results reveal that optimizing heat pump system sizing improves annualized costs and emissions for six examined buildings by up to 8.2% in costs and 12.7% in emissions compared to sizings derived by the conventional design procedure VDI4645. To exploit even further potential, the integration of operational optimization within the design is highly recommended. In addition, a more detailed modeling approach of the building should be implemented in HPS eOD Design. Both measures lead to an acceleration of the building sector defossilization.

Abstract Before new technologies enter the market, their environmental superiority over competing options must be asserted based on a life cycle approach. However, when applying the prevailing status-quo Life Cycle Assessment (LCA) approach to future renewable energy systems, one does not distinguish between impacts which are ‘imported’ into the system due to the ‘background system’ (e.g. due to supply of materials or final energy for the production of the energy system), and what is the improvement potential of these technologies compared to competitors (e.g. due to process and system innovations or diffusion effects). This paper investigates a dynamic approach towards the LCA of renewable energy technologies and proves that for all renewable energy chains, the inputs of finite energy resources and emissions of greenhouse gases are extremely low compared with the conventional system. With regard to the other environmental impacts the findings do not reveal any clear verdict for or against renewable energies. Future development will enable a further reduction of environmental impacts of renewable energy systems. Different factors are responsible for this development, such as progress with respect to technical parameters of energy converters, in particular, improved efficiency; emissions characteristics; increased lifetime, etc.; advances with regard to the production process of energy converters and fuels; and advances with regard to ‘external’ services originating from conventional energy and transport systems, for instance, improved electricity or process heat supply for system production and ecologically optimized transport systems for fuel transportation. The application of renewable energy sources might modify not only the background system, but also further downstream aspects, such as consumer behavior. This effect is, however, strongly context and technology dependent.

Resilience as a descriptive concept gives insight into the dynamic properties of an ecological-economic system. Sustainability as a normative concept captures basic ideas of intergenerational justice when human well-being depends on natural capital and services. Thus, resilience and sustainability are independent concepts. In this paper, we discuss the relationship between resilience and sustainability of ecological-economic systems. We use a simple dynamic model where two natural capital stocks provide ecosystem services that are complements for human well-being, to illustrate different possible cases of the relationship between resilience and sustainability, and to identify the conditions under which each of those will hold: a) resilience of the system is necessary, but not sufficient, for sustainability; b) resilience of the system is sufficient, but not necessary, for sustainability; c) resilience of the system is neither necessary nor sufficient for sustainability; and d) resilience is both necessary and sufficient for sustainability. We conclude that more criteria than just resilience have to be taken into account when designing policies for the sustainable development of ecological-economic systems, and, vice versa, the property of resilience should not be confused with the positive normative connotations of sustainability. (C) 2011 Elsevier B.V. All rights reserved.