Brazil plans to meet the majority of its growing electricity demand with new hydropower plants located in the Amazon basin. However, large hydropower plants located in tropical forested regions may ...lead to significant carbon dioxide and methane emission. Currently, no predictive models exist to estimate the greenhouse gas emissions before the reservoir is built. This paper presents two different approaches to investigate the future carbon balance of eighteen new reservoirs in the Amazon. The first approach is based on a degradation model of flooded carbon stock, while the second approach is based on flux data measured in Amazonian rivers and reservoirs. The models rely on a Monte Carlo simulation framework to represent the balance of the greenhouse gases into the atmosphere that results when land and river are converted into a reservoir. Further, we investigate the role of the residence time stratification in the carbon emissions estimate. Our results imply that two factors contribute to reducing overall emissions from these reservoirs: high energy densities reservoirs, i.e., the ratio between the installed capacity and flooded area, and vegetation clearing. While the models' uncertainties are high, we show that a robust treatment of uncertainty can effectively indicate whether a reservoir in the Amazon will result in larger greenhouse gas emissions when compared to other electricity sources.
Malaysia's transportation sector accounts for 41% of the country's total energy use. The country is expected to become a net oil importer by the year 2011. To encourage renewable energy development ...and relieve the country's emerging oil dependence, in 2006 the government mandated blending 5% palm-oil biodiesel in petroleum diesel. Malaysia produced 16 million tonnes of palm oil in 2007, mainly for food use. This paper addresses maximizing bioenergy use from oil-palm to support Malaysia's energy initiative while minimizing greenhouse-gas emissions from land-use change. When converting primary and secondary forests to oil-palm plantations between 270–530 and 120–190
g CO
2-equivalent per MJ of biodiesel produced, respectively, is released. However, converting degraded lands results in the capture of between 23 and 85
g CO
2-equivalent per MJ of biodiesel produced. Using various combinations of land types, Malaysia could meet the 5% biodiesel target with a net GHG savings of about 1.03 million tonnes (4.9% of the transportation sector's diesel emissions) when accounting for the emissions savings from the diesel fuel displaced. These findings are used to recommend policies for mitigating GHG emissions impacts from the growth of palm oil use in the transportation sector.
► We modeled greenhouse gas emissions in the production of palm-biodiesel. ► Five land types were included to model emissions associated with land-use change. ► Land-use change has the biggest impact on the emissions in making palm-biodiesel. ► Emissions from fertilizer use and effluent treatment are still significant. ► At 5% biodiesel grown on suitable lands Malaysia would obtain an emissions savings.
Liquid transportation fuels derived from coal and natural gas could help the United States reduce its dependence on petroleum. The fuels could be produced domestically or imported from fossil ...fuel-rich countries. The goal of this paper is to determine the life-cycle GHG emissions of coal- and natural gas-based Fischer−Tropsch (FT) liquids, as well as to compare production costs. The results show that the use of coal- or natural gas-based FT liquids will likely lead to significant increases in greenhouse gas (GHG) emissions compared to petroleum-based fuels. In a best-case scenario, coal- or natural gas-based FT-liquids have emissions only comparable to petroleum-based fuels. In addition, the economic advantages of gas-to-liquid (GTL) fuels are not obvious: there is a narrow range of petroleum and natural gas prices at which GTL fuels would be competitive with petroleum-based fuels. CTL fuels are generally cheaper than petroleum-based fuels. However, recent reports suggest there is uncertainty about the availability of economically viable coal resources in the United States. If the U.S. has a goal of increasing its energy security, and at the same time significantly reducing its GHG emissions, neither CTL nor GTL consumption seem a reasonable path to follow.
Resumen Introducción: La pandemia actual representa un reto para la atención hospitalaria, los servicios de cirugía cardiovascular han modificado su funcionamiento y están constantemente evaluando el ...riesgo cardiovascular frente al riesgo de la COVID-19. Objetivo: Caracterizar el funcionamiento de 23 centros cardiovasculares de Colombia, con el fin de generar información que permita optimizar los servicios y evitar muertes de causa cardiovascular prevenibles. Método: Estudio observacional transversal con fuente primaria de información. Muestra por conveniencia de 23 centros cardiovasculares de Colombia. Resultados: Se encontró que el 39.1% de los centros suspendieron la actividad en algún momento entre enero y mayo de 2020 y el 34.8% han tenido una disminución en la actividad del servicio del 76-100%; en los meses de abril y mayo se encontró una reducción de alrededor del 50% con referencia a los primeros 2 meses. De las 2258 intervenciones realizadas, solo el 0.17% fueron en pacientes con COVID-19. El estudio muestra que el 60.1% de los servicios han presentado problemas con la utilización de elementos de protección personal. El 17.4% de los centros realizan reacción en cadena de la polimerasa para el virus de forma sistemática en el prequirúrgico, y el 44% la realiza a pacientes con síntomas respiratorios. Conclusiones: Durante la pandemia se requiere una detección temprana de posibles infectados que vayan a cirugía, adaptar la programación y promocionar un adecuado uso de los equipos de protección personal. Urge aplicar estrategias dirigidas a pacientes que no pueden ser postergados para evitar segundas y terceras víctimas de la pandemia.
This work performed a phenotypic and genotypic characterization of 79 clinical isolates of Enterobacteriaceae and Pseudomonadaceae collected in hospitals of Southern Ecuadorin 2013. Our results ...showed a high incidence of β-lactamases and ESBLs with blaTEM and blaCTX-M as the prevalent genes, respectively. By direct sequencing of PCR amplicons, the different β-lactamases and variants of the genes were also distinguished. Our results revealed a predominance of TEM-1 β-lactamase and the presence of different CTX-M variants with a prevalence of CTX-M-15. Two infrequent CTX-M variants in South America were also identified. To the best of our knowledge, this is one of the first studies describing the genetic characteristics of β-lactamases in Ecuador.
Projections of increased domestic natural gas supply and low prices have encouraged increased natural gas utilization in the United States electricity sector. Natural gas can offset coal, likely ...decreasing overall greenhouse gas (GHG) emissions and other air emissions such as SO2 and NOX. Previous life cycle assessment (LCA) studies using limited system boundaries have attempted to quantify the benefit of offsetting coal use. However, these studies do not consider that relative regional fuel prices may contribute most to the choice of coal over natural gas. External incentives such as low natural gas prices compared to coal are required if natural gas is to displace coal. In this study, simplified economic dispatch models are used to determine how natural gas utilization will increase in the short-term in response to changes in natural gas prices in three US grid regions-ERCOT, MISO and PJM. The results indicate that the change in air emissions is lower than suggested by LCAs, since LCAs generally do not include the complexity of regional electricity grids. For instance, this study estimates that life cycle GHG emissions may, at best, decrease by 7-15% due to low natural gas prices, compared to almost 50% reductions estimated by previous LCAs.
Day-ahead load and wind power forecasts provide useful information for operational decision making, but they are imperfect and forecast errors must be offset with operational reserves and balancing ...of (real time) energy. Procurement of these reserves is of great operational and financial importance in integrating large-scale wind power. We present a probabilistic method to determine net load forecast uncertainty for day-ahead wind and load forecasts. Our analysis uses data from two different electric grids in the US with similar levels of installed wind capacity but with large differences in wind and load forecast accuracy, due to geographic characteristics. We demonstrate that the day-ahead capacity requirements can be computed based on forecasts of wind and load. For 95% day-ahead reliability, this required capacity ranges from 2100 to 5700 MW for ERCOT, and 1900 to 4500 MW for MISO (with 10 GW of installed wind capacity), depending on the wind and load forecast values. We also show that for each MW of additional wind power capacity for ERCOT, 0.16-0.30 MW of dispatchable capacity will be used to compensate for wind uncertainty based on day-ahead forecasts. For MISO (with its more accurate forecasts), the requirement is 0.07-0.13 MW of dispatchable capacity for each MW of additional wind capacity.
•We quantify the benefits of controlled charging of plug-in hybrid electric vehicles.•Costs are determined using an economic dispatch and unit commitment model.•The model is based on New York ISO and ...allows for capacity expansion.•We find controlled charging can significantly lower system costs.•Controlled charging benefits are larger with high wind penetration.
Electric power systems with substantial wind capacity require additional flexibility to react to rapid changes in wind farm output and mismatches in the timing of generation and demand. Controlled variable-rate charging of plug-in electric vehicles allows demand to be rapidly modulated, providing an alternative to using fast-responding natural gas plants for balancing supply with demand and potentially reducing costs of operation and new plant construction. We investigate the cost savings from controlled charging of electric vehicles, the extent to which these benefits increase in high wind penetration scenarios, and the trade-off between establishing a controlled charging program vs. increasing the capacity of generators in the power system. We construct a mixed integer linear programming model for capacity expansion, plant dispatch, and plug-in hybrid electric vehicle (PHEV) charging based on the NYISO system. We find that controlled charging cuts the cost of integrating PHEVs in half. The magnitude of these savings is ∼5% to 15% higher in a system with 20% wind penetration compared to a system with no wind power, and the savings are 50–60% higher in a system that requires capacity expansion.
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