26 Matching Annotations
  1. May 2020
    1. los autobuses escolares equipados con Wi-Fi se estacionan durante la noche en los barrios marginales para que los niños puedan conectarse y realizar sus tareas; o el caso de niños que acuden a las bibliotecas locales y a las cadenas de comida rápida para acceder a puntos de acceso gratuitos2

      Esta sería una excelente idea para apoyar las dificultades de conectividad que se presenta en las familias de escasos recursos yasi apoyarlos en sus procesos escolares durante el confinamiento.

  2. Mar 2018
    1. Additionally, battery disposal would require that fresh metals be mined for cathode material, and mining has a much bigger environmental impact and cost than simple recycling would.
    2. Modern elec tronics, however, place significantly greater demands on the longevity and mass of batteries.
    3. Modern electronic devices, such as cell phones, computing devices, and automobiles, demand substantial current delivery while being lightweight and Small enough to avoid hindering the portability of the host device.
  3. www.nature.com.wdg.biblio.udg.mx:2048 www.nature.com.wdg.biblio.udg.mx:2048
    1. Thedevelopmentofnewrechargeablebatterysystemscouldfuelvar-iousenergyapplications, frompersonalelectronics togridstorage
  4. www.nature.com.wdg.biblio.udg.mx:2048 www.nature.com.wdg.biblio.udg.mx:2048
    1. The reason why we are facing the present global energy and environment crisis is due to the fact that we have violated the time–matter cycle by rapidly consuming for the past 200  years fossil fuels that took millions of years to be formed and accumulated.
    2. Concerns regarding the ‘green’ quality of batteries have long existed and over the years these concerns have been addressed in a vari-ety of ways. We must now address the issue of chemical toxicity in batteries head-on by identifying non-toxic element and additive alternatives with similar performance to their toxic counterparts
    3. The reason why we are facing the present global energy and environment crisis is due to the fact that we have violated the time–matter cycle by rapidly consuming for the past 200  years fossil fuels that took millions of years to be formed and accumulated.
    4. Li-ion batteries do not contain any of these materials but 3d metals such as nickel or cobalt are used in most of them. Their use together with lithium is problematic due to limited supply, their continuously increasing cost and the environ-mentally questionable extraction methods.
    5. Li-ion batteries do not contain any of these materials but 3d metals such as nickel or cobalt are used in most of them. Their use together with lithium is problematic due to limited supply, their continuously increasing cost and the environ-mentally questionable extraction methods.
    6. The foreseen demand for lithium, dictated by the expanding electric vehicle and grid applications, brings fear of lithium shortage. It also raises geopolitical issues related to uneven global distribution of lith-ium around the world.
    7. batteries will only begin to have an environmental benefit beyond hundreds of cycles. This also questions the benefits of developing batteries for electric vehi-cles to decrease greenhouse-gas emissions when we heavily rely on coal-fired plants to produce primary electricity.
    8. developing Li-ion batteries for transport and that are able to deal with society’s fluctuating energy needs is a formidable chal-lenge, especially from a materials perspective. In addition to the classical figures of merit (specific energy and power, lifetime, cost and safety), other issues are not yet fully recognized, such as the low relative abundance of materials (lithium is already viewed by some alarmists as the gold of this next century) and the large energy cost of battery manufacture and recycling.

      Desventajas del uso de Litio

    9. If we are unsuccessful in jointly capturing, managing and storing energy at a large scale and low cost, our only recourse will be to drastically reduce our total energy consumption.
    10. we currently only have the capacity to store around 1% of the energy consumed worldwide, most of which (98%) is through pumped-storage hydroelectricity
    11. Ever-growing energy needs and depleting fossil-fuel resources demand the pursuit of sustainable energy alternatives, includ-ing both renewable energy sources and sustainable storage technologies
    1. In short, we require methods to establish the health record of the battery, analogous to personal health records for human beings.
    2. We need new analytical methods, optimized to probe specific battery chemistries, so that new technologies can be brought to the market more rapidly to meet societal demands.
    3. Si, has received considerable attention, because its capacity is 10 times that of carbon. But the Li-alloying reactions (LixSi, where x ≤ 3.75) are accompanied by extremely large volume changes, owing to the large amount of inserted Li
    4. But these advances do not address concerns about lim-ited Li reserves, which result from the predicted increased battery demands
    5. Although progress has been encouraging, it is certainly not sufficient to meet our planet’s growing demands: we must push the frontiers faster and further in the years to come.
    6. they have revealed that today’s battery assembly process, including materials and recycling, is not as sustainable as generally thought, 400 kWh of energy being required to make batteries that deliver 1 kWh of energy, while releasing 75 kg of CO2
    7. can we increase battery sustain-ability, while lowering cost and improving battery performance?

      ...

    8. the production of Li-ion batter-ies should expand hugely over the years to come, hence reviving the issue of finite Li reserves.
    1. gran inconveniente asociado al uso de combustibles fósiles es de carácter ecológico, y se ve directamente influenciado por las crecientes exigencias por parte de la sociedad de disminuir las emisiones de gases de efecto invernadero, resultantes de la quema de estos combustibles. Bajo esta perspectiva, el ser humano se encuentra forzado a voltear su mirada a la producción de energía eléctrica utilizando tecnologías alternas que representen una solución sustentable, a fin de solventar la creciente demanda energética a nivel mundial.

      Principal problemática.

    1. El panorama para la demanda energética mundial, proyecta un crecimientosignificativo durante el periodo de 28 años desde 2012 al 2040 según el International Energy Outlook(2016). El consumo total de energía comercializada estabapor 549 cuatrillones de unidades térmicas británicas (Btu)(138,452 Ptoe)en el 2012, pasaráa 629 cuatrillones de Btu(158,627 Ptoe)en el 2020 y de alcanzará 815 cuatrillones de Btu(205,535 Ptoe)en el 2040;es decir se podrá experimentar un aumento del 48% desde el2012 al2040

      La problemática del consumo de la energía eléctrica va en aumento cada día.