Gara Villalba Méndez

Material Flow Analysis of Scarce Metals: Sources, Functions, End-Uses and Aspects for Future Supply

A number of metals that are now important to the electronic industry (and others) will become much more important in the future if current trends in technology continue. Most of these metals are byproducts (or hitch-hikers) of a small number of important industrial metals (attractors). By definition, the metals in the hitch-hiker group are not mined by themselves, and thus their production is limited by the demand for the major attractors. This article presents a material flow analysis (MFA) of the complex inter-relationships between these groups of metals. First, it surveys the main sources of geologically scarce (byproduct) metals currently considered critical by one or other of several recent studies. This is followed by a detailed survey of their major functions and the quantities contained in intermediate and end-products. The purpose is to identify the sectors and products where those metals are used and stocked and thus potentially available for future recycling. It concludes with a discussion of the limitations of possible substitution and barriers to recycling.

Material and Energy Requirement for Rare Earth Production

The use of rare earth metals (REMs) for new applications in renewable and communication technologies has increased concern about future supply as well as environmental burdens associated with the extraction, use, and disposal (losses) of these metals. Although there are several reports describing and quantifying the production and use of REM, there is still a lack of quantitative data about the material and energy requirements for their extraction and refining. Such information remains difficult to acquire as China is still supplying over 95% of the world REM supply. This article attempts to estimate the material and energy requirements for the production of REM based on the theoretical chemical reactions and thermodynamics. The results show the material and energy requirement varies greatly depending on the type of mineral ore, production facility, and beneficiation process selected. They also show that the greatest loss occurs during mining (25–50%) and beneficiation (10–30%) of RE minerals. We hope that the material and energy balances presented in this article will be of use in life cycle analysis, resource accounting, and other industrial ecology tools used to quantify the environmental consequences of meeting REM demand for new technology products.

Increasing Precision in Greenhouse Gas Accounting Using Real‐Time Emission Factors

For many companies, the greenhouse gas (GHG) emissions associated with their purchased and consumed electricity form one of the largest contributions to the GHG emissions that result from their activities. Currently, hourly variations in electricity grid emissions are not considered by standard GHG accounting protocols, which apply a national grid emission factor (EF), potentially resulting in erred estimates for the GHG emissions. In this study, a method is developed that calculates GHG emissions based on real‐time data, and it is shown that the use of hourly electricity grid EFs can significantly improve the accuracy of the GHG emissions that are attributed to the purchased and consumed electricity of a company. A model analysis for the electricity delivered to the Spanish grid in 2012 reveals that, for companies operating during the day, GHG emissions calculated by the real‐time method are estimated to be up to 5% higher (and in some special cases up to 9% higher) than the emissions calculated by the conventional method in which a national grid EF is applied, whereas for companies operating during nightly hours, GHG emissions are estimated to be as low as 3% below the GHG emissions determined by the conventional method. A significant error can therefore occur in the organizational carbon footprint (CF) of a company and, consequently, also in the product CF. It is recommended that hourly EFs be developed for other countries and power grids.

Recycling Rare Metals

Abstract The industrial system now utilizes many more elements, especially rare metals, than was the case even a half century ago. Most are not mined for themselves but are obtained as by-products or “hitchhikers” of the more familiar industrial metals, such as iron, aluminum, copper, nickel, and zinc. This imposes a limit on the production of by-product metals. But in some cases, demand may increase much faster than new supply. This suggests a need for recycling. But the uses of these metals are often in products, such as cell phones, that are mass-produced but where the amount in each individual product is very small. Some uses are also inherently dissipative. This makes recycling very difficult in principle. It constitutes a serious challenge for the future economy. Prices will rise.

Energy Intensity of the Catalan Construction Sector

We used a thermodynamic framework to characterize the resource consumption of the construction sector in 2001 in Catalonia, the northeast region of Spain. The analysis was done with a cradle�?to�?product life cycle approach using material flow analysis (MFA) and exergy accounting methodologies to quantify the total material and energy inputs in the sector. The aim was to identify the limitations of resource metabolism in the sector and to pinpoint the opportunities for improved material selection criteria, processing, reuse, and recycling for sustainable resource use. The results obtained from MFA showed that nonrenewables such as minerals and natural rocks, cement and derivatives, ceramics, glass, metals, plastics, paints and other chemicals, electric and lighting products, and bituminous mix products accounted for more than 98% of the input materials in the construction sector. The exergy analysis quantified a total 113.1 petajoules (PJ) of exergy inputs in the sector; utilities accounted for 57% of this exergy. Besides exergy inputs, a total of 6.85 million metric tons of construction and demolition waste was generated in 2001. With a recycling rate of 6.5%, the sector recovered 1.3 PJ of exergy. If the sector were able to recycle 80% of construction and demolition waste, then exergy recovery would be 10.3 PJ. Hence the results of this analysis indicate that improvements are required in manufacturing processes and recycling activities, especially of energy�?intensive materials, in order to reduce the inputs of utilities and the extraction of primary materials from the environment.

Decentralized Wastewater Systems in Bengaluru, India: Success or Failure?

Decentralized wastewater treatment and reuse (DWTRU) using small-scale on-site sewage treatment plants (STPs) is an attractive solution addressing the problems of water pollution and scarcity, especially in rapidly urbanizing cities in developing countries, where centralized infrastructure for wastewater treatment is inadequate. But decentralized systems face several challenges (economic feasibility, public acceptance) that need to be better understood. The city of Bengaluru in India provides an excellent opportunity to evaluate such systems. In 2004, in an effort to curb the alarming levels of pollution in its water bodies due to untreated sewage disposal, the environmental regulatory agency mandated apartment complexes above a certain size to install STPs and reuse 100% of their wastewater, resulting in the installation of more than 2200 on-site STPs till date. This study attempts to analyze the factors influencing the extent of treatment and reuse in such systems, through structured surveys of residential associations, STP experts and government officials. The results are analyzed using a framework that integrates the technology adoption literature with the monitoring and enforcement literature. The study indicates that, while no apartment complex is able to reuse 100% of its treated water, there exists significant variation across apartment complexes in the level of treatment and reuse (from partial to poor) due to a complex mix of economies of scale, the price of fresh water, the level of enforcement and awareness, and technological choices made under information asymmetry. Only apartments dependent on expensive tanker water supply had clear economic incentives to comply with the order. Yet many large complexes that depended on low-priced utility or borewell supply were partially compliant, owing partly to lower (although positive) costs, higher level of formal enforcement and perhaps greater environmental awareness. On the other hand, the high treatment cost pushed smaller complexes to curtail the operation of their STPs (and the lower levels of enforcement further worsened this), resulting in inadequate treated water quality and consequently low reuse levels. The study recommends relaxing the infeasible 100% reuse criterion, and raising the threshold size above which DWTRU should be mandated so as to reduce the cost burden and increase enforceability. Subsidies towards capital costs and enabling resale of treated water will enable wider adoption. DWTRU is an apparently attractive solution that however, requires judicious policy-making and implementation to succeed.

Exergetic Life Cycle Assessment: An Improved Option to Analyze Resource Use Efficiency of the Construction Sector

This article presents an effort to pinpoint how efficiently resources are used in the construction sector applying exergetic life cycle assessment methodology in a cradle-to-grave life cycle approach. Polypropylene (PP) and polyvinyl chloride (PVC), two widely used thermoplastics in construction applications, are chosen as case study materials in this analysis involving raw material extraction, resin manufacturing, and post-consumer waste management life-cycle stages. Overall life cycle exergy efficiency of PP and PVC is quantified 27.1% and 9.3%, respectively, characterized by a low efficiency of manufacturing and recycling processes for both materials. Improving the efficiency of manufacturing and recycling processes will thus reduce exergy losses from the system. From resource conservation point of view, mechanical recycling can be the viable option for end-of-life plastic waste management, since it loops materials back directly into new life cycle, and thus reduces primary resource inputs in the production chain and associated environmental impacts.

Exergy analysis of construction material manufacturing processes and assessment of their improvement potentials

This study presents the application of exergy analysis in assessing how effectively resources are utilised in construction material manufacturing. The role of exergy is discussed from several key perspectives such as quality, energy conservation and process improvement potentials. Both primary and secondary processes (recycling) of nine major non–renewable construction materials (steel, aluminium, copper, cement, concrete, ceramic, glass, polypropylene and polyvinylchloride (PVC)) have been evaluated in this study. The outlined theoretical exergy efficiency approach assesses the improvement potentials of the present manufacturing processes. The large difference between theoretical and industrial exergy demand suggests that exergy resources are utilised very inefficiently in current technologies. The study reveals that more than 55% of exergy is being lost in current technologies even though a significant amount of waste heat is recovered in different segments of the case study processes. Thus, attention is required to reduce the specific exergy losses through improved process design and introduction of new technology.