To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Plastics generally play a very important role in a plethora of industries, fields and our everyday lives. In spite of their cheapness, availability and important contributions to lives, they however, pose a serious threat to the environment due to their mostly non-biodegradable nature. Recycling into useful products can reduce the amount of plastic waste. Thermal degradation (Pyrolysis) of plastics is becoming an increasingly important recycling method for the conversion of plastic materials into valuable chemicals and oil products. In this work, waste Polyethylene terephthalate (PET) water bottles were thermally converted into useful gaseous and liquid products. A simple pyrolysis reactor system has been used for the conversions with the liquid product yield of 65 % at a temperature range of 400°C to 550°C. The chemical analysis of the pyrolytic oil showed the presence of functional groups such as alkanes, alkenes, alcohols, ethers, carboxylic acids, esters, and phenyl ring substitution bands. The main constituents were 1-Tetradecene, 1-Pentadecene, Cetene, Hexadecane, 1-Heptadecene, Heptadecane, Octadecane, Nonadecane, Eicosane, Tetratetracontane, 1-Undecene, 1-Decene). The results are promising and can be maximized by additional techniques such as hydrogenation and hydrodeoxygenation to obtain value-added products.
Predicting the impact of SDG 6 on forests and forest people requires a balanced understanding of the relationship between forests and water. Notable aspects are that forest cover reduces annual runoff but correlates well with water quality, and that recycling of evapotranspiration from forests is important for downwind precipitation. Within this context a target-by-target review of SDG 6, informed by South American examples, suggests that the Goal is unlikely to exert a major influence on forest cover. Targets 6.1 and 6.2 concerning water and sanitation provision will have relatively little impact on forests except through a demand for hydrological ecosystem services and the use of wastewater in forestry. Within the four water resources targets (6.3–6.6) significant impacts may be limited to water efficiency considerations (Target 6.4) restricting plantations in water-stressed areas and Integrated Water Resources Management (Target 6.5) driving a more integrated view of catchments and their management. The eventual SDG 6 impact will depend on the context of water–forest relationships (illustrated using the Hindu Kush Himalayas as an example), the extent to which SDG 6 will in fact be implemented and alignment of the Goal with forest policies, based on a landscape approach.
Composite materials, or at least materials that could be regarded as composites, are widespread in nature. This is, of course, a reflection of the many gains in ‘efficiency’ that can be made by integration of two or more constituents. Moreover, the development of artificial composite materials, for mechanical and/or other purposes, has benefited considerably from insights gained by examining bio-composites, and by their direct utilisation. The kingdoms of both plants (wood, grasses, straw, etc.) and animals (bone, skin, teeth, marine shells, corals, etc.) offer many examples of highly successful materials that are essentially composites. Their importance relates not only to lessons about structure–property relationships, but also to the issue of degradation and recycling. While the ‘rotting’ of wood is often regarded as its Achilles’ heel, viable recycling strategies are increasingly required for all materials (and manufactured composites are often perceived as being unsatisfactory in this respect). It is clearly not appropriate in a book of this type to provide great detail about natural materials, or indeed about recycling, but a few of the main principles and issues involved are briefly summarised here.
Cast iron objects recovered primarily in eastern Mongolia, spanning the Xiongnu through the Early Historic periods (ca. 3rd BC–AD 17th century), were examined for their radiocarbon (14C) concentration and microstructure. Most of the samples examined were found to have originated from charcoal-based smelting with a few exceptions that were made using a mineral coal-based technique. A comparison of 14C dates with dates derived from artifact typology allowed the charcoal-smelted objects to be classified into two groups, based on whether the radiometric and typological periodization are in agreement or not. In addition, those with differing 14C and typological dates can be divided into two subgroups with and without evidence for a melt treatment applied after original casting. These conflicting dating results are confusing and would seem to provoke skepticism about the use of 14C measurements for dating iron artifacts. We demonstrate however that 14C analysis, when combined with metallographic examination and other lines of chronological evidence, can clarify the history of a given iron object and its multiple users, often separated in time by more than a millennium.
Diverse theoretical perspectives suggest that place plays an important role in human behavior. One recent perspective proposes that habitual and recursive use of places among humans may be an emergent property of obligate tool use by our species. In this view, the costs of tool use are reduced by preferential occupation of previously occupied places where cultural materials have been discarded. Here we use the model to generate five predictions for ethnographic mobility patterns. We then test the predictions against observations made during one month of coresidence with a residentially mobile Dukha family in the Mongolian Taiga. We show that (1) there is a strong tendency to occupy previously used camps, (2) previously deposited materials are habitually recycled, (3) reoccupation of places transcends kinship, (4) occupational hiatuses can span decades or longer, and (5) the distribution of occupation intensity among camps is highly skewed such that most camps are not intensively reoccupied whereas a few camps experience extremely high reoccupation intensity. These findings complement previous archaeological findings and support the conclusion that the constructed dimensions of human habitats exert a strong influence on mobility patterns in mobile societies.
Since the earliest stages of international climate policy, carbon dioxide (CO2) has been framed and widely accepted as a problem that needs to be solved by reducing its amount in the atmosphere. In principle this is a correct and relevant starting point for efforts to decarbonize societies. At the same time, however, the unquestioned and one-sided framing of CO2 as a problem has significantly biased the strategies for tackling climate change. We introduce the origins, meanings and implications of one-sided framing of CO2 in climate policy. We also discuss how alternative framings could impact policymaking and eventually our capacity to mitigate climate change. We introduce a paradox: framing CO2 as a problem often translates into policies that hamper the implementation of technologies to decrease the amount of CO2 emitted into the atmosphere. We suggest that plurality in framing CO2 could lead to innovative ways and strategies to combat climate change.
In light of growing demand and pollution versus a finite amount of resources, electronic waste recycling is a way towards material circularity. New recycling technologies not only face technical difficulties but also need to overcome challenges of feasibility in both economic and environmental aspects. An assessment regarding environmental impacts and economic factors at the early development stages of such technologies is necessary to ensure a successful establishment. A batch lab-scale process using bioleaching to win indium from electronic waste was drafted using recent research in the field. Life Cycle Assessment (LCA) was used to determine the environmental impacts in four different categories at the lowest Technology Readiness Level (TRL). The findings were then compared to two existing chemical leaching processes to put them in perspective. Results show that the electricity consumption is the major contribution to environmental impacts. The assumed bioleaching process has a higher environmental impact than the two chemical processes due to its high duration and resulting high electricity consumption. However, the research has also proven, that an LCA during the conceptual phase has a high uncertainty due to lack of data and knowledge about the process.
Disordered iron oxide thin-films synthesized from grain-oriented iron foils were grown on both glass and Si (100) n-type substrates by vacuum evaporation followed by thermal oxidation at low temperatures. Defects such as vacancies formation has been studied using Atomic Force Microscopy (AFM) and Raman Spectroscopy. The kinetic of oxidation as a function of surface parameters was investigated by AFM studies. The vibrational modes (bands) connected with the vacancies formation and magnetic ordering into the iron oxide structure were validated by Raman spectroscopy. Space-charge effects can be influenced by discontinuous growth of iron oxide and correlated with their structure parameters. Finally, the disordered iron oxide will be useful for the next generation of adaptive oxide devices.
Recent progress in semiconductor materials with minor nonradiative recombination has stimulated investigations of novel photovoltaic (PV) converters with optical control of radiative emission. Angle restricted emission was experimentally demonstrated in PV devices with external photon recycling due to specific photonic crystals or mirrors. In this work we investigate the power beam conversion by the cell with front “greenhouse” filter, which transmits the laser light, but recycles the low energy bandgap quanta emitted by the semiconductor cell. We calculate the limiting characteristics of the greenhouse PV converters and optimize design of the converter taking into account the nonradiative recombination processes. In optimized devices addition of the greenhouse filter can increase power beam conversion efficiency by several percent.
FERC Order 841 focused on standardizing electric storage resource (ESR) participation in wholesale energy, ancillary services, and capacity market ruleset, by treating storage as a generation resource. Treatment of storage as a transmission asset (SATA) is up in the air. Expect to see FERC action on ISO/RTO compliance plans in 2019.
Energy storage is finally getting its due at the wholesale grid level, thanks to FERC Order 841. All the grid operators within FERC jurisdiction must comply with FERC order to allow “electric storage resource” to participate in their markets. Storage increases capacity value of renewables and decreases variability as the grid makes way for more renewables such as wind and solar. Market Monitors must understand that storage could “withhold” its capacity in early morning ramp hours for evening peak ramp hours, or participate in ancillary services regulation market without bidding into the energy market. At the same time, this resource could be a transmission asset, adding an additional level of complexity. This FERC Order 841 has its own challenges: (i) it treats storage as a generation asset, (ii) some (such as National Association for Utility Regulators) think FERC stepped on their toes, (iii) it does not address all the value stack benefits for storage-like transmission for example, and (iv) aggregation of distribution connected storage is side stepped. So the industry is watching for clear direction from their Federal regulator on this important technology, which is finally getting its due.
TiO2 has been widely studied as a photocatalytic material due to its non-toxicity, chemical inertness, and high photocatalytic activity. Here, we explore the operational behavior of a novel TiO2 micropillars array being developed to use solar radiation to treat recycled wastewater in long-duration space missions. A Light Capture model was developed to model light absorption. The Lattice Boltzmann method was used to simulate water flow, and the finite element method was used to model waste mass transfer.
Exact solution of the generalized Shockley – Queisser model provides simple and effective tool for modeling of photovoltaic (PV) and thermophotovoltaic (TPV) devices with advanced photonic management. This formalism takes into account spectral characteristics of absorption/emission and a variety of recombination processes in semiconductor cell. In the current work we generalize this formalism to devices with non-ideal light reflectors used for light recycling and trapping. As an example, we investigate effects of the light management in InGaAsSb TPV converters (0.53 eV bandgap) with back surface reflector and with an additional front surface scattering layer, which provides Lambertian trapping of photons. We calculate the output power (efficiency) and investigate tradeoff between photon absorption and Auger recombination processes as a function of the device thickness. Finally, we compare performance of these TPV devices with the performance of traditional devices.
Today, processing technologies have generated negative environmental impact as emission of toxic gases and degradation of the earth when certain products are placement in landfills leading to environmental pollution and several health risks, which damage societies to sustain the planet for future generations. As electronics waste, grain-oriented iron foils, graphite films and Mn-Zn ferrites have been identified as interesting candidates. Uncommon physical properties from such materials are available when these are converting technologically. A strategy such as Life-Cycle Assessment is employed here to taking into account all stages of the life cycle of electronics waste, including processing technology, manufacturing processes, use phase, and end-of-life routes to quantify the recycling performance as a function of the physical parameters that will characterize operability of a functional device. Hence, structure and conduction properties in waste materials are exploring by using Raman spectroscopy and electrical characterization techniques. Researching waste materials will provide theoretical basis for open-loop recycling, where trends related to green engineering must be attained with recyclable materials for practical adaptive structures using different performance principles compared to those used in silicon devices.
Mineral phosphorus (P) used to fertilise crops is derived from phosphate rock, which is a finite resource. Preventing and recycling mineral P waste in the food system, therefore, are essential to sustain future food security and long-term availability of mineral P. The aim of our modelling exercise was to assess the potential of preventing and recycling P waste in a food system, in order to reduce the dependency on phosphate rock. To this end, we modelled a hypothetical food system designed to produce sufficient food for a fixed population with a minimum input requirement of mineral P. This model included representative crop and animal production systems, and was parameterised using data from the Netherlands. We assumed no import or export of feed and food. We furthermore assumed small P soil losses and no net P accumulation in soils, which is typical for northwest European conditions. We first assessed the minimum P requirement in a baseline situation, that is 42% of crop waste is recycled, and humans derived 60% of their dietary protein from animals (PA). Results showed that about 60% of the P waste in this food system resulted from wasting P in human excreta. We subsequently evaluated P input for alternative situations to assess the (combined) effect of: (1) preventing waste of crop and animal products, (2) fully recycling waste of crop products, (3) fully recycling waste of animal products and (4) fully recycling human excreta and industrial processing water. Recycling of human excreta showed most potential to reduce P waste from the food system, followed by prevention and finally recycling of agricultural waste. Fully recycling P could reduce mineral P input by 90%. Finally, for each situation, we studied the impact of consumption of PA in the human diet from 0% to 80%. The optimal amount of animal protein in the diet depended on whether P waste from animal products was prevented or fully recycled: if it was, then a small amount of animal protein in the human diet resulted in the most sustainable use of P; but if it was not, then the most sustainable use of P would result from a complete absence of animal protein in the human diet. Our results apply to our hypothetical situation. The principles included in our model however, also hold for food systems with, for example, different climatic and soil conditions, farming practices, representative types of crops and animals and population densities.
The recent financial crisis highlighted the limits of the originate to distribute model of banking, but its nexus with the macroeconomy remains unexplored. I build a business cycle model with banks engaging in credit risk transfer (CRT) under informational externalities. Markets for CRT provide liquidity insurance to banks, but the emergence of a pooling equilibrium can also impair the banks' monitoring incentives. In normal times and in face of standard macro shocks the insurance benefits of CRT prevail and the business cycle is stabilized. In face of financial/liquidity shocks the extent of informational asymmetries is larger and the business cycle is amplified. The macro model with CRT can also reproduce well a number of macro and banking statistics over the period of rapid growth of this banks' business model.
Concerted efforts by stakeholders could overcome the hurdles and enable a viable recycling system for automotive LIBs by the time many of them go out of service.
Lithium-ion batteries (LIBs) were commercialized in the early 1990s and gained popularity first in consumer electronics, then more recently for electric vehicle (EV) propulsion, because of their high energy and power density and long cycle life. Their rapid adoption brings with it the challenge of end-of-life waste management. There are strong arguments for LIB recycling from environmental sustainability, economic, and political perspectives. Recycling reduces material going into landfills and avoids the impacts of virgin material production. LIBs contain high-value materials like cobalt and nickel, so recycling can reduce material and disposal costs, leading to reduced EV costs. Battery recycling can also reduce material demand and dependence on foreign resources, such as cobalt from Democratic Republic of the Congo, where much production relies on armed aggression and child labor.
Several companies are finding ways to commercialize recycling of the increasingly diverse LIB waste stream. Although Pb-acid battery recycling has been successfully implemented, there are many reasons why recycling of LIBs is not yet a universally well-established practice. Some of these are technical constraints, and others involve economic barriers, logistic issues, and regulatory gaps. This paper first builds a case as to why LIBs should be recycled, next compares recycling processes, and then addresses the different factors affecting LIB recycling to direct future work towards overcoming the barriers so that recycling can become standard practice.
New demand for electric vehicles—are rare earths the bottleneck in the supply chain? Can recycling and substitution make a dent in the demand for REE in the near future? Is it economically feasible for advanced nations to mine for REE but process them elsewhere to allay environmental concerns at home?
Rare earths are critical components to many technologies that drive the modern world. Though rare earths are present in most parts of the world, they are produced mostly in China because of a confluence of several factors. This paper reviews various aspects of rare earths including extraction, geopolitics, and challenges. Rare-earth elements (REEs) not only replace each other in the mineral structure but also occur within different mineral structures in the same deposit. Separation of one REE from another is therefore difficult, environmentally challenging, and expensive. Less than 1% of REEs is recycled due to many challenges of collecting various end products and separating the REE from other metals/contaminants. Recycling investments have primarily focused on applications such as magnets, where economies of scale have allowed it. Substitution for the REE is difficult for most applications, though the automotive and wind energy industries are making good advances with motors and generators. The rare earth market is small and, thus, easily disrupted. Factors that can impact the market are increased production from existing mines, development of mine prospects advanced during price spikes, research and development efforts focused on improving REE recoveries, recycling, substitution, alternate sources of REEs, and governmental policies.
Environmentally aware automotive manufacturers recycle aluminum production scrap in closed-loop systems to generate environmental and financial savings. Further savings could be gained if material demand is reduced, through improving the material utilization of the production process. Since a more efficient production process generates less scrap, the opportunity for closed loop recycling reduces when material demand reduces. This paper investigates the interaction between material demand reduction and closed loop recycling for an aluminum intensive case-study vehicle. It identifies the greatest environmental and financial savings when both strategies are implemented together. It is shown that a ‘recycled content’ target does not capture these saving opportunities. It is recommended that automotive manufacturers set targets for both material utilization and scrap recovery, to simultaneously promote closed-loop recycling and material demand reduction.
An effective way to reduce the impact of cement production on the environment is to use supplementary cementitious materials (SCM) as a partial substitution to cement. In addition to the reduction in cost and energy saving, the use of SCM in cement for the manufacture of mortar and concrete offers technical advantages. In this paper, cement was partially substituted by fines obtained from crushed recycled bricks recovered from a brick plant. The level of substitution was either 0%, 5%, 10% or 15% by weight of cement. The results show that cement substitution by brick fines resulted in a slight loss of workability with the increase of the substitution rate. Substitutions rates of 5% and 10% produced at long-term comparable strength as control mortars. The differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA) results show cement hydration improved significantly with different rates of substitutions at 28 and 180 days of age.
This paper explores the development of tile-stamping in the period a.d. 100–50 by the Gloucester and Cirencester civic authorities, and by private tile-makers in Gloucestershire, and the territorial divisions between them. It argues that builders’ merchants were used in tile distribution and building reclamation and, inter alia, identifies Hucclecote villa as such a site. It proposes that Gloucester tiles stamped just RPG were issued annually and were used for commercial purposes while tiles with magistrates’ names were issued as required, but only for use on public buildings. The evidence suggests that these stamps were subsequently extensively curated. This paper adds nearly 200 new stamps to the existing catalogues and proposes significant revisions to the magistrate dies as a result.