The private and social economics of bulk electricity storage

The ability to store excess intermittent renewable electricity is increasingly being seen as a key option for integrating large quantities of renewable capacity. However, intermittent energy sources currently account for very small amounts of total generation. Despite this fact, policymakers have begun implementing requirements that will dramatically increase the amount of bulk storage capacity. This paper examines the social benefits provided by bulk storage in the Texas electricity market, which has a large amount of renewable capacity relative to other states, but still quite limited renewable penetration. We focus on the impact of arbitraging electricity across time—a major service of bulk storage. Using current storage technologies, we demonstrate that electricity arbitrage will increase daily CO₂ emissions by an average of 0.19 tons for each MWh stored. In addition, daily SO₂ emissions will increase by an average of 1.89 pounds/MWh while NO_X emissions will fall by an average of 0.15 pounds/MWh.     

Physico-chemical characteristics of fine fraction materials from an old crystal glass dumpsite in Sweden

Physico-chemical characteristics of waste, particularly fine fraction (FF), from an old crystal glass waste dump in Sweden were studied to assess recycling or disposal alternatives. Hand-sorting of the waste indicated glass content of 44.1% while sieving established the FF as a more soil-like mix of glass and other materials constituting 33.3% of all excavated waste. The FF was around neutral pH with 24.4% moisture content, low values of Total Dissolved Solids, Dissolved Organic Carbon and fluorides, but hazardous concentrations of As, Cd, Pb and Zn according to the Swedish Environmental Protection Agency guidelines. While the FF leached metals in low concentrations at neutral pH, it leached considerably during digestion with nitric acid, implying leaching risks at low pH. Thus, the waste requires safe storage in hazardous waste class ‘bank account’ storage cells to avoid environmental contamination as metal recovery and other recycling strategies for the glass waste are being developed. The study could fill the information gap regarding preservation of potential resources in the on-going, fast-paced excavation and re-landfilling of heavy metal contaminated materials in the region.     

Resilience to natural hazards: How useful is this concept?

Resilience is widely seen as a desirable system property in environmental management. This paper explores the concept of resilience to natural hazards, using weather-related hazards in coastal megacities as an example. The paper draws on the wide literature on megacities, coastal hazards, hazard risk reduction strategies, and resilience within environmental management. Some analysts define resilience as a system attribute, whilst others use it as an umbrella concept for a range of system attributes deemed desirable. These umbrella concepts have not been made operational to support planning or management. It is recommended that resilience only be used in a restricted sense to describe specific system attributes concerning (i) the amount of disturbance a system can absorb and still remain within the same state or domain of attraction and (ii) the degree to which the system is capable of self-organisation. The concept of adaptive capacity, which has emerged in the context of climate change, can then be adopted as the umbrella concept, where resilience will be one factor influencing adaptive capacity. This improvement to conceptual clarity would foster much-needed communication between the natural hazards and the climate change communities and, more importantly, offers greater potential in application, especially when attempting to move away from disaster recovery to hazard prediction, disaster prevention, and preparedness.     

Treatability aspects of urban stormwater stressors

Pollution from diffuse sources (pollution from contaminants picked up and carried into surface waters by stormwater runoff) has been identified as a significant source of water quality problems in the U.S. scientists and engineers continue to seek solutions that will allow them to optimize existing technologies and develop new ones that will provide the best possible protection to people, wildlife, and the environment. This paper addresses the various pollutants or stressors in urban stormwater, including flow (shear force), pathogens, suspended solids/sediment, toxicants (organic and metals), nutrients, oxygen demanding substances, and coarse solids. A broad overview of the pollutants removed and the removal mechanisms by and of conventional best management practices (BMPs) is also presented. The principal treatment mechanisms of conventional wet ponds, vegetative swales/buffer strips, and wetlands are sedimentation and filtration. These mechanisms have the capability to remove significant amounts of suspended solids or particulate matter and are a vital component of strategies to reduce pollutant loads to receiving waters. In addition, because most of the nation??s receiving water violations are caused by pathogen indicator bacteria, it is of utmost importance that research efforts address this problem. Further research is also needed on the treatment of emerging contaminants in BMPs and on the costs and affects of maintenance and maintenance schedules on the long-term performance of BMPs.     

Short- and long-term consistency in the foraging niche of wandering albatrosses

The wandering albatross (Diomedea exulans) is regarded as a generalist predator, but can it be consistent in its foraging niche at an individual level? This study tested short- and long-term consistency in the foraging niche in terms of habitat use, trophic level and, by inference, prey selection. Fieldwork was carried out at Bird Island, South Georgia, in May–October 2009, during the chick-rearing period. Blood (plasma and cells) and feathers for stable isotope analyses (δ¹³C and δ¹⁵N) were sampled from 35 adults on their return from a foraging trip during which they carried stomach temperature, activity and global positioning system loggers. Results suggest short-term consistency in foraging niche in relation to both oceanic water mass and trophic level, and long-term consistency in use of habitat. Consistent differences between individuals partly reflected sex-specific habitat preferences. The proportion of consistent individuals (i.e., with a narrow foraging niche) was estimated at c. 40?% for short-term habitat and trophic level (prey) preferences and 29?% for longer-term habitat preference, suggesting this is an important characteristic of this population and potentially of pelagic seabirds in general. Foraging consistency was not related to body condition or level of breeding experience; instead, it may reduce intraspecific competition.     

A journey into Process Safety with Trevor Kletz

I offer a personal perspective on the Process Safety contributions of Trevor Kletz and how his lessons have helped shaped both my career and my own views on the topic.     

Using carbon and nitrogen isotopic values of body feathers to infer inter- and intra-individual variations of seabird feeding ecology during moult

To determine whether stable isotope measurements of body feathers can be used to investigate the isotopic niche of moulting (inter-nesting) adult seabirds, we examined the stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic composition of body feathers of breeding wandering albatrosses (Diomedea exulans) from Crozet Islands, southern Indian Ocean. First we showed that the isotopic composition of body feathers was not significantly different from that of wing feathers, being thus a safe alternative to flight feathers whose collection impairs the birds’ flying ability. Second, we looked at the variances in δ¹³C and δ¹⁵N values resulting from the isotopic measurement of a single feather, four different feathers, and a pool of four feathers per bird, to delineate the best isotopic analytical procedure. A two-step protocol is proposed that allows investigating both the intra- and inter-individual components of the niche width of the species. In a first step, isotopic measurements on a single feather per bird are used to define isotopic specialist from isotopic generalist populations. In a second step and for generalist populations only, measurements on additional (three) feathers per bird are used to delineate type A from type B isotopic generalists (Bearhop et al. in J Anim Ecol 73:1007–1012, 2004). Third, from a biological point of view, our data showed different moulting isotopic niches for adult males and females, and also within female wandering albatrosses. Since the isotopic composition of body feathers in this species reflects that of wing feathers, our results suggest that, after validation, body feathers have the potential for investigating the foraging ecology of other Procellariiforms and seabirds during the poorly known inter-nesting period.     

Social network analysis and valid Markov chain Monte Carlo tests of null models

Analyses of animal social networks derived from group-based associations often rely on randomisation methods developed in ecology (Manly, Ecology 76:1109–1115, 1995) and made available to the animal behaviour community through implementation of a pair-wise swapping algorithm by Bejder et al. (Anim Behav 56:719–725, 1998). We report a correctable flaw in this method and point the reader to a wider literature on the subject of null models in the ecology literature. We illustrate the importance of correcting the method using a toy network and use it to make a preliminary analysis of a network of associations among eagle rays.

Animal social networks: an introduction

Network analysis has a long history in the mathematical and social sciences and the aim of this introduction is to provide a brief overview of the potential that it holds for the study of animal behaviour. One of the most attractive features of the network paradigm is that it provides a single conceptual framework with which we can study the social organisation of animals at all levels (individual, dyad, group, population) and for all types of interaction (aggressive, cooperative, sexual etc.). Graphical tools allow a visual inspection of networks which often helps inspire ideas for testable hypotheses. Network analysis itself provides a multitude of novel statistical tools that can be used to characterise social patterns in animal populations. Among the important insights that networks have facilitated is that indirect social connections matter. Interactions between individuals generate a social environment at the population level which in turn selects for behavioural strategies at the individual level. A social network is often a perfect means by which to represent heterogeneous relationships in a population. Probing the biological drivers for these heterogeneities, often as a function of time, forms the basis of many of the current uses of network analysis in the behavioural sciences. This special issue on social networks brings together a diverse group of practitioners whose study systems range from social insects over reptiles to birds, cetaceans, ungulates and primates in order to illustrate the wide-ranging applications of network analysis. This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and R. James).