• Energy Research
• other engineering and technologies close
• 12. Responsible consumption close
• 6. Clean water close
• DE close
• NL close

This study focuses on formulating the most sustainable concrete by incorporating recycled concrete aggregates and other products retrieved from construction and demolition (C&D) activities. Both recycled coarse aggregates (RCA) and recycled fine aggregates (RFA) are firstly used to fully replace the natural coarse and fine aggregates in the concrete mix design. Later, the cement rich ultrafine particles, recycled glass powder and mineral fibres recovered from construction and demolition wastes (CDW) are further incorporated at a smaller rate either as cement substituent or as supplementary additives. Remarkable properties are noticed when the RCA (4–12 mm) and RFA (0.25–4 mm) are fully used to replace the natural aggregates in a new concrete mix. The addition of recycled cement rich ultrafines (RCU), Recycled glass ultrafines (RGU) and recycled mineral fibres (RMF) into recycled concrete improves the modulus of elasticity. The final concrete, which comprises more than 75% (wt.) of recycled components/materials, is believed to be the most sustainable and green concrete mix. Mechanical properties and durability of this concrete have been studied and found to be within acceptable limits, indicating the potential of recycled aggregates and other CDW components in shaping sustainable and circular construction practices. The authors wish to acknowledge the financial support from EU Horizon 2020 Project VEEP ‘‘Cost-Effective Recycling of C&DW in High Added Value Energy Efficient Prefabricated Concrete Compo-nents for Massive Retrofitting of our Built Environment” (No.723582).

Given the global energy and environmental situation, the European Union has been issuing directives with increasingly demanding requirements in term of the energy efficiency in buildings. The international competition of sustainable houses, Solar Decathlon Europe (SDE), is aligned with these European objectives. SDE houses are low energy solar buildings that must reach the near to zero energy houses’ goal. In the 2012 edition, in order to emphasize its significance, the Energy Efficiency Contest was added. SDE houses’ interior comfort, functioning and energy performance is monitored. The monitoring data can give an idea about the efficiency of the houses. However, a jury comprised by international experts is responsible for carrying out the houses energy efficiency evaluation. Passive strategies and houses services are analyzed. Additionally, the jury's assessment has been compared with the behavior of the houses during the monitoring period. Comparative studies make emphasis on the energy aspects, houses functioning and their interior comfort. Conclusions include thoughts related with the evaluation process, the results of the comparative studies and suggestions for the next competitions.

As part of the Copenhagen Accord, individual countries have submitted greenhouse gas reduction proposals for the year 2020. This paper analyses the implications for emission reductions, the carbon price, and abatement costs of these submissions. The submissions of the Annex I (industrialised) countries are estimated to lead to a total reduction target of 12-18% below 1990 levels. The submissions of the seven major emerging economies are estimated to lead to an 11-14% reduction below baseline emissions, depending on international (financial) support. Global abatement costs in 2020 are estimated at about USD 60-100 billion, assuming that at least two-thirds of Annex I emission reduction targets need to be achieved domestically. The largest share of these costs are incurred by Annex I countries, although the costs as share of GDP are similar for Annex I as a group and the seven emerging economies as a group, even when assuming substantial international transfers from Annex I countries to the emerging economies to finance their abatement costs. If the restriction of achieving two-thirds of the emission reduction target domestically is abandoned, it would more than double the international carbon price and at the same time reduce global abatement costs by almost 25%.

SummaryThe German government has adopted a law that requires sewage plants to go beyond the recovery of phosphorus from wastewater and to promote recycling. We argue that there is no physical global short‐ or mid‐term phosphorus scarcity. However, we also argue that there are legitimate reasons for policies such as those of Germany, including: precaution as a way to ensure future generations’ long‐term supply security, promotion of technologies for closed‐loop economics in a promising stage of technology development, and decrease in the current supply risk with a new resource pool.

The Flameless Combustion (FC) regime has been pointed out as a promising combustion technique to lower the emissions of nitrogen oxides (NOx) while maintaining low CO and soot emissions, as well as high efficiencies. However, its accurate modeling remains a challenge. The prediction of pollutant species, especially NOx, is affected by the usually low total values that require higher precision from computational tools, as well as the incorporation of relevant formation pathways within the overall reaction mechanism that are usually neglected. The present work explores a multiple step modeling approach to tackle these issues. Initially, a CFD solution with simplified chemistry is generated [both the Eddy Dissipation Model (EDM) as well as the Flamelet Generated Manifolds (FGM) approach are employed]. Subsequently, its computational cells are clustered to form ideal reactors by user-defined criteria, and the resulting Chemical Reactor Network (CRN) is subsequently solved with a detailed chemical reaction mechanism. The capabilities of the clustering and CRN solving computational tool (AGNES—Automatic Generation of Networks for Emission Simulation) are explored with a test case related to FC. The test case is non-premixed burner based on jet mixing and fueled with CH4 tested for various equivalence ratios. Results show that the prediction of CO emissions was improved significantly with respect to the CFD solution and are in good agreement with the experimental data. As for the NOx emissions, the CRN results were capable of reproducing the non-monotonic behavior with equivalence ratio, which the CFD simulations could not capture. However, the agreement between experimental values and those predicted by CRN for NOx is not fully satisfactory. The clustering criteria employed to generate the CRNs from the CFD solutions were shown to affect the results to a great extent, pointing to future opportunities in improving the multi-step procedure and its application.

The selection of an appropriate “optimal” recycling alternative has to take into consideration both the ecological and economic effects of the entire life-cycle. The aim of this paper is to compare different waste management systems by means of a life-cycle assessment (LCA) and a cost comparison. The analysis uses data regarding the amount of household waste generated, collected and treated in a selected area in Austria. For this purpose, model-based scenarios with recycling and separate collection as well as scenarios without recycling were created. The database covers the amounts of household waste generated in the different collection schemes, the transport distances by private delivery and by regional waste management companies and data on the waste treatment processes that are widely employed throughout Austria and Germany. The resulting life-cycle inventories have been assessed according to three impact categories relevant to this topic—the global warming potential (GWP), the acidification potential (AP) and the net energy use (NEU). The results include ecological impact analyses and cost comparisons for the overall waste management systems and the waste management systems for the individual waste types—waste paper, plastic packaging, metal packaging and waste glass. Finally, a sensitivity analysis should prove the validity of the results for regions with transport distances differing from those in the area under analysis. © 2003 Elsevier B.V. All rights reserved.

Abstract Rare earth permanent magnets are important components for modern (energy) technologies and are employed to reduce GHG emissions and combat climate change. The process of extracting these minerals from the ore has contentious economic, environmental and social implications. While the environmental impacts of their production have already been analyzed in several studies, the economic and the social perspective is still under-researched. The Social Life Cycle Assessment (S-LCA) approach employed in the present research explores whether there is a difference in social risks for rare earth permanent magnet production from three different rare earth ore production locations and the associated value chains. While one is located completely in China, another is composed of processes in Australia and Malaysia. The third process chain combines processes in the United States and Japan. The Product Social Impact Life Cycle Assessment (PSILCA) 2.0 database is used to assess the social implications. The analysis focuses on value chain actors, a stakeholder group of great interest to businesses but often underrepresented in S-LCA research. The impact categories describing this stakeholder group pertain to issues of social responsibility along the value chain, fair competition and corruption. Overall, the US value chain indicates the lowest level of social risk along the supply chain. However, in order to gain a deeper understanding of the social risks a sectoral and geographical analysis is conducted. Across all three cases, the mineral, fossil fuel and chemical sectors are shown to be problematic.