Leveling coatings for reducing the atomic oxygen defect density in protected graphite fiber epoxy composites

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low Earth orbit to reach underlying material. One concept of enhancing the lifetime of materials in low Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface tension leveling coating concept, a low viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 A of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/sq cm were reduced to about 1000 defects/sq cm as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/sq cm

Policy trade-offs between climate mitigation and clean cook-stove access in South Asia

Household air pollution from traditional cook stoves presents a greater health hazard than any other environmental factor. Despite government efforts to support clean-burning cooking fuels, over 700 million people in South Asia could still rely on traditional stoves in 2030. This number could rise if climate change mitigation efforts increase energy costs. Here we quantify the costs of support policies to make clean cooking affordable to all South Asians under four increasingly stringent climate policy scenarios. Our most sringent mitigation scenario increases clean fuel costs 38% in 2030 relative to the baseline, keeping 21% more South Asians on traditional stoves or increasing the minimum support policy cost to achieve universal clean cooking by up to 44%. The extent of this increase depends on how poliymakers allocate subsidies between clean fuels and stoves. These additional costs are within the range of financial transfers to South Asia estimated in efforts-sharing scenarios of international climate agreements. Three billion people globally burn solid fuels such as firewood, charcoal, coal, dung, and crop resides in open fires and traditional stoves for cooking and heating. Household air pollution from the incomplete combustion of these fuels globally leads to 4.3 million premature deaths each year, with 1.7 million of those in South Asia. This exceeds the burden of disease from any other energy-related or environmental risk factor. Solid-fuel use also perpetuates income and gender inequality by forcing users, mostly poor women and children, to spend long hours collecting fuels and to suffer from its adverse health effects. To address this problem, the United Nations Secretary-General's Sustainable Energy for All (SE4All) initiative and the new Sustainable Development Goals aim to achieve universal access to modern energy services by 2030. Numerous intervention efforts have focused on distributing more efficient and cleaner burning biomass stoves, but several of these programmes have had little or no demonstrable impact on health outcomes. In India, the nation with the largest population of solid-fuel users globally, government interventions have sought to make petroleum-based fuels, such as kerosene and liquefied petroleum gas (LPG), more affordable through subsidy at an estimated cost of over US$6 billion per year. Although LPG use has grown rapidly, particularly in rural areas, over 72% of Indians continued to rely primarily on solid fuels in 2012. In the future, expanding clean cooking may become more challenging if climate policies increase the cost of fuels. Previous research has found that greenhouse gas (GHG) emissions reductions in Asia and Africa would increase the cost of kerosene and LPG. However, these studies do not explore compensatory policies that could counteract these effects, and assess only a limited set of climate mitigation scenarios. Only two studies explore normative scenarios that achieve access and climate goals simultanously, both of which do not explore the cost-effectiveness or distributional impacts on population subgroups of these policies. Meanwhile, studies that have evaluated the cost-effectiveness of energy access policies have not considered the impact of climate policy. Te latest assessment of the Intergovernmental Panel on Climate Change (IPCC) concludes that we have only low confidence in our understanding of the possible impacts of climate policy on access to modern energy services, and medium confidence in the policies needed to counteract them. In this study, we contribute new insights to the interaction of climate policy and clean cooking acces policies by quantifying the feasibility and costs of achieving universal access by 2030 for a range of climate policy stringencies, and under a wide range of fuel and stove price support policies. Our analysis suggests that the potential trade-offs between the two goals might be arger than suggested by previous studies. However, we find that efficient policy design could partially compensate for the additional access policy costs associated with climate mitigation. Furthermore, these costs fall below the level of potential financial transfers to South Asia that may result from international climate agreements

Stranded on a low-carbon planet: Implications of climate policy for the phase-out of coal-based power plants

Limiting global warming to 2 degrees C will likely entail the complete phase-out of coal-based electricity generation without carbon capture and storage (CCS). The timing and rate of this phase-out will depend on the stringency of near-term climate policy and will have important implications for the stranding of coal power plant capacity without CCS. The objectives of this paper are to better understand the relationship between near-term climate policy and stranded coal capacity (assuming a long-term goal of limiting warming to 2 degrees C) and to explore strategies for reducing stranded capacity. Our analysis suggests that strengthening near-term climate policy (i.e., lowering the global greenhouse gas emission target in 2030) generally reduces stranded coal capacity and its costs. An effective strategy for reducing stranded capacity is to minimize new construction of coal capacity without CCS, which can be accomplished by reducing electricity demand through energy intensity improvements and/or by keeping existing plants operating through lifetime extensions. Another strategy, providing emission exemptions for pre-existing coal plants (i.e., grandfathering), would eliminate stranded capacity, but also decreases the likelihood of achieving the 2 degrees C target. Finally, the ability of CCS retrofits to significantly reduce stranded capacity depends on how quickly the technology can be deployed

University space planning and space-type profiles

Universities planning the provision of space for their teaching requirements need to do so in a fashion that reduces capital and maintenance costs whilst still providing a high-quality level of service. Space plans should aim to provide sufficient capacity without incurring excessive costs due to over-capacity. A simple measure used to estimate over-provision is utilisation. Essentially, the utilisation is the fraction of seats that are used in practice, or the ratio of demand to supply. However, studies usually find that utilisation is low, often only 20–40%, and this is suggestive of significant over-capacity. Our previous work has provided methods to improve such space planning. They identify a critical level of utilisation as the highest level that can be achieved whilst still reliably satisfying the demand for places to allocate teaching events. In this paper, we extend this body of work to incorporate the notions of event-types and space-types. Teaching events have multiple ‘event-types’, such as lecture, tutorial, workshop, etc., and there are generally corresponding space-types. Matching the type of an event to a room of a corresponding space-type is generally desirable. However, realistically, allocation happens in a mixed space-type environment where teaching events of a given type are allocated to rooms of another space-type; e.g., tutorials will borrow lecture theatres or workshop rooms. We propose a model and methodology to quantify the effects of space-type mixing and establish methods to search for better space-type profiles; where the term “space-type profile” refers to the relative numbers of each type of space. We give evidence that these methods have the potential to improve utilisation levels. Hence, the contribution of this paper is twofold. Firstly, we present informative studies of the effects of space-type mixing on utilisation, and critical utilisations. Secondly, we present straightforward though novel methods to determine better space-type profiles, and give an example in which the resulting profiles are indeed significantly improved. <br/

Quantifying uncertainties influencing the long-term impacts of oil prices on energy markets and carbon emissions

Oil prices have fluctuated remarkably in recent years. Previous studies have analysed the impacts of future oil prices on the energy system and greenhouse gas emissions, but none have quantitatively assessed how the broader, energy-system-wide impacts of diverging oil price futures depend on a suite of critical uncertainties. Here we use the MESSAGE integrated assessment model to study several factors potentially influencing this interaction, thereby shedding light on which future unknowns hold the most importance. We find that sustained low or high oil prices could have a major impact on the global energy system over the next several decades; and depending on how the fuel substitution dynamics play out, the carbon dioxide consequences could be significant (for example, between 5 and 20% of the budget for staying below the internationally agreed 2 ∘C target). Whether or not oil and gas prices decouple going forward is found to be the biggest uncertainty

Supporting the Dynamic Careers of Licensed Practical Nurses: A Strategy to Bolster the Long-Term Care Nurse Workforce

As the U.S. population ages and the demand for long-term care increases, an insufficient number of licensed practical nurses (LPNs) is expected in the nursing workforce. Understanding the characteristics of LPN participation in the workforce is essential to address this challenge. Drawing on the theory of boundaryless careers, the authors examined longitudinal employment data from LPNs in North Carolina and described patterns in LPN licensure and career transitions. Two career patterns were identified: (a) the continuous career, in which LPNs were licensed in 75% or more of the years they were eligible to be licensed and (b) the intermittent career, in which lapses in licensure occurred. Findings indicated that LPNs who made job transitions were more likely to demonstrate continuous careers, as were Black LPNs. These findings suggest the importance of organizational support for LPN career transitions and support for diversity in the LPN workforce

Energy Investments under Climate Policy: A Comparison of Global Models

The levels of investment needed to mobilize an energy system transformation and mitigate climate change are not known with certainty. This paper aims to inform the ongoing dialogue and in so doing to guide public policy and strategic corporate decision making. Within the framework of the LIMITS integrated assessment model comparison exercise, we analyze a multi-IAM ensemble of long-term energy and greenhouse gas emissions scenarios. Our study provides insight into several critical but uncertain areas related to the future investment environment, for example in terms of where capital expenditures may need to flow regionally, into which sectors they might be concentrated, and what policies could be helpful in spurring these financial resources. We find that stringent climate policies consistent with a 2 degrees C climate change target would require a considerable upscaling of investments into low-carbon energy and energy efficiency, reaching approximately $45 trillion (range:$30-75 trillion) cumulative between 2010 and 2050, or about $1.1 trillion annually. This represents an increase of some$30 trillion ($10-55 trillion), or$0.8 trillion per year, beyond what investments might otherwise be in a reference scenario that assumes the continuation of present and planned emissions-reducing policies throughout the world. In other words, a substantial "clean-energy investment gap" of some $800 billion/yr exists -- notably on the same order of magnitude as present-day subsidies for fossil energy and electricity worldwide ($523 billion). Unless the gap is filled rather quickly, the 2 degrees C target could potentially become out of reach

Chapter 2: What emission levels will comply with temperature limits?

Over the past few years rapid progress has been made in understanding the impacts of greenhouse gas emissions on global warming. This understanding has also made it possible to better estimate the levels of global emissions consistent with global temperature increase limits, such as 1.5 degrees C and 2 degrees C. This chapter first reviews estimates of recent global emission levels and trends; then examines business-as-usual emission levels that would theoretically be reached if no further action were taken to reduce emissions. Finally, it presents the levels of emissions that are consistent with limits to global temperature increases