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Everything posted by Moreno

  1. If our Universe is infinite in time and space and physical reality preserves its key elements forever, does it mean that all people who once died are destined to resurrect somewhere in space and time and will practically never die?
  2. 1) The question is how we define "the space". There is no absolutely evident border between atmosphere and the space. 2) The space race never ends. It just only started. Russians, Chinese, Indians could be the first on Mars, Venus etc. And don't forget the other galaxies.
  3. Why small intestine needs to neutralize the acid?
  4. What could be an evolutionary purpose to have digestive system strictly differentiated into the stomach, small intestine and large intestine? Is it too difficult to have a single organ which can perform the functions of all the three? For example something similar to a large intestine?
  5. Is it possible to create some coktail of nanoparticles which absorb all the radiation between 300 MHz and 3GHz? And convert this radiation into heat?
  6. I think it is disappointing that laws of our universe do not permit to create a practical engines which would work without entropy change (and therefore wouldn't require constant fuel supply). Even though such engines may not contradict to the formal 3 laws of thermodynamics. Or they do?
  7. Sodium-ion batteries have even lower energy density than Li-ion, what cannot solve the quest.
  8. So, what kind of battery do you think of?
  9. Why Sodium? It is difficult to store. It cannot be stored on open air and will explode on contact with water.
  10. I agree on that. Thermodynamically there is no difference if we burn Lithium on air with help of fire or if we "burn" it in electrochemical element. In idealized case it should release the same amount of energy. But practically efficiency of metal-air fuel cells (as well as any other batteries) never get close to 100%.
  11. So what are you trying to prove me and what is your point? Any metal-air battery is rather an energy storage device than an energy source. There is no pure metal in nature, typically, with exception of the midgets, you need to take energy sourse somewhere to get free metal or recharge metal-air battery. Thermodinamically efficiency of metal-air batteries can approach efficiency of Li-ion batteries very closely, the differences are rather chemical than thermodynamical. My point was that you need more kg of Lithium to save the same amount of energy in Li-ion battery than if you would make react Lithium with air in idealized conditions, so knowing how much energy does Lithium-Oxygen reaction releases gives you a starting point to estimate how many kg of Lithium you will need in a typical car which runs on Li-ion batteries (quite a many).
  12. And how high voltage suppose to be to make tunneling effect significant? Could you give some links?
  13. It is quite similar. In metal-air fuel cells or batteries a metal reacts with oxygen and releases energy. In idealized case it releases as much energy as if we just burn this metal on air. Some of such batteries can be even rechargeable. For example Zinc-air. There are some experiments on Li-air. Other batteries are similar. In Li-Silfur Lithium reacts with Sulfur instead of Oxygen, in Li-ion it intercalactes into a host material (typically an oxide). But the basic principle is no different from Li-air. Obviously Li-air battery going to give more energy per weight of Lithium than Li-ion because reaction with Oxigen is more energetic one than reaction of intercalation.
  14. I think the same issue, probably, may be related to all the typical electrolytic capacitors.
  15. It seems in a dry Tantalum capacitor a thin (few nanometers) layer of Tantalum oxide separates electron conducting metallic Tantalum and hole conducting semiconductor (typically MO2). How in this case a huge charge leakage through quantum tunneling is prevented? For example Aluminum in normal conditions is also covered with thin layer of Aluminum oxide, but it doesn't prevent us to get electrocuted if we touch live Aluminum wire. Because layer of Aluminum oxide is too thin to prevent quantum tunneling of electrons. Why in Tantalum capacitors it should be different?
  16. Is biodiesel from algae cheaper than gasoline? At present it is more expensive, and gasoline, in its turn, is several times more expensive than electricity which is used to power EVs. Aluminum price is mostly defined by price of electricity which could be quite cheap at night or at remote areas. Also EVs are cheaper initially, and maitenance is cheaper too.
  17. I think it would be interesting to have comparison of a car which runs on biofuel with car which runs on metal powder. The later is basically EV and typically 3 times more efficient. It is simpler, cheaper and releases zero gaseous exhaust in the cities. Electricity from the cheap sources could be cheaper than biofuel (as it is now), I think.
  18. I'm talking about energy that Lithium releases in ideal conditions reacting with air and forming Lithium ...oxides. In Li-ion, Li-sulfur, etc. batteries Lithium produces even less energy than that (per kg), by definition, so you need to account to use even more Lithium per km (that vehicle passes) than in Li-air batteries (if they will be ever suitable for use in EV vehicles).
  19. Lithium energy density per weight is around 50 MJ/Kg, Sodium around 15 MJ/Kg and gasoline - 45 MJ kg. So, there is no way you can have just 20 kg of Li even in sedan, not talking about trucks and pickups. Even at 100% battery efficiency (what is unlikely).
  20. I've read some critical opinions about OLED screens, that colors they depict are too unnatural and hence LCDs are much better. I wish to know more opinions on that subject. Also how QLEDs compare to both OLEDs and LCD in terms of quality?
  21. If someone wants to use solar energy to power cars, then the simplest solution is biofuel. No need for any solar panels. It would be interesting to find out a comparison between biofuel cars and EVs in terms of price, costs and efficiency. In this case, Metal-air fuel cells and metal powder is the most reasonable way to accomplish this with near future technology. They could be used efficiently not only in cars, but also in trains, ships, agricultural machinery, perhaps even in airbuses, if some new type of propulsion drive will be invented.
  22. So, you propose to use 1 ton Li-ion batteries in each vehicle? Can you imagine their cost and size? I rather thought about Li-air or Li-Sulfur if they well be ever suitable to use them in cars. There is plenty of hydro and geothermal energy in remote places (for example in Iceland or Siberia), it is just inconvenient to transmit electricity from there. I think using Aluminum as an energy carrier may help to solve this problem. It could be smelted on place and Aluminum powder transported by cargo vessels. I think subcritical nuclear reactors (those which use particle accelerators) may create a backbone of power generation in the nearest 100 years. They are quite safe, can burn Thorium, Uranium of any kind and even nuclear waste. And remain quite a few waste after them.
  23. According to this picture there exist a certain bandgap (over 1 eV) in Lead between the lowest band (which I assume corresponds to some hole states) and all other bands (which I assume correspond to all other electron and hole states). Does it mean that Lead is a unique metal with band gap between a hole and electron states? Does it suppose to have some semiconducting properties then? https://www.researchgate.net/figure/Color-online-Calculated-band-structure-of-bulk-lead-with-solid-lines-and-without_fig1_45935753
  24. 1) Nuclear, hydro and geothermal energies are also net energy positive. Aluminum is just a way to store this energy. 2) Aluminum oxide dropped on the roads will be not much different from common sand and will be quickly blown out by the wind. An interest in recycling may appear only if entire heaps of it will start to collect in the large cities. I'm not sure there going to be any principal difference in price of Aluminum from recycled Aluminum oxide and bauxite ore.
  25. Because EVs are more efficient you may require fewer kg of Aluminum per km than kg of gasoline.
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