Converting human energy to electricity

Discussion in 'General Electronics Chat' started by MrSoftware, Apr 4, 2017.

  1. cmartinez

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    High enough, and it wouldn't take any effort at all!
     
  2. WBahn

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    Yes, but would that height be above or below the point where the cyclist couldn't put out any effort at all?
     
  3. Alec_t

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    You would have to factor in the energy needed to get cyclist + cycle + oxygen bottles etc up to that height :).
     
  4. cmartinez

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    Right. I'm too wondering if there's an optimal altitude for an athlete (or a normal person) at which there's a minimum effort to make that happen. But people become adapted to different altitudes, depending on where they were born and raised.

    I wonder if this feat would be easier for an athlete living in La Paz, Bolivia, than for another living in Miami.
     
  5. WBahn

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    It probably would, but that's not really relevant since we aren't talking about person A compared to person B (or at least I don't think we are). But it would also be interesting to see if the optimal altitude is markedly different for people acclimated to different altitudes and, if it is, whether the optimal altitude for high-altitude residents is higher or lower than the optimal altitude for low-altitude residents. I think I can envision rational explanations for either outcome.
     
  6. cmartinez

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    I remember back in '68, in the olimpic games in Mexico city, many a fine athlete were severely affected by the city's altitude, and many underperformed. Some even passed out after giving their best effort at whatever sport they were participating at. And of course, the most affected were the ones whose hometowns were at sea level.
     
  7. WBahn

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    But high-altitude athletes generally perform better at lower altitude than they do at their training altitudes. But their improvement as they go downward doesn't match the loss in performance as low-altitude athletes experience as they go upward. So, for any pair of such athletes, there is a crossover altitude at which the effects neutralize and who will win is anyone's guess. It's like the classic match-ups of many dissimilar competitors -- you craft an event that crosses between the realm where one dominates to the one that the other dominates, there's a sweet spot where they are evenly matched. Whether it's a human sprinter versus a quarter horse or a jet fighter versus a sports car.
     
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  8. wayneh

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    If the water to be boiled is sufficiently insulated, then their is little additional heat required to raise it from a reduced boiling point to regular boiling temps. Those last few degrees take far less heat than it does to actually boil enough water to be considered boiling. The heat required to boil off some quantity of water will be essentially the same at any temperature.

    So my hypothesis is that there won't be a sweet spot. The job will be uniformly easier as oxygen for the human increases. Death Valley should be even better.

    I know I'm sidestepping the theoretical experiment in favor of a real one. If the experiment never actually boils water, then there might still be room for a sweet spot above sea level.
     
  9. WBahn

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    That may well be the case. It really depends on the relative slopes of the two curves. You have the curve of the total amount of energy required to boil the water and the total amount of energy that the cyclist can produce. Both curves slope downward at all points as altitude increases (for water that's definitely the case, and I think it's a reasonable assumption for the cyclist, too, especially on a stationary bike). If the downward slope for the water is steeper than for the cyclist, then we can start off with an amount of water that the cyclist can't boil at sea level but can boil at a higher altitude. Your reasoning about the amount of energy being only slightly dependent on altitude equates to saying that the downward slope of the curve for water is very shallow. If it is shallower than the curve for the cyclist (which if very well may be) then if the cyclist can boil a given amount of water at altitude, they can boil it at sea level. But I don't think the reasoning applies forever. As you go to negative altitude (say in a chamber), the energy required to boil the water will continue to increase as pressure increases. But I don't think the cyclist's ability to produce energy will increase to keep pace -- his body will reach a point where it simply cannot utilize the additional oxygen that's available and increasing the pressure further will reduce his output as his body has to work harder to move the increasing larger mass of air in and out of his lungs with each breath. So his total energy output will actually start decreasing as you go to even lower altitudes. In theory, this peak point could actually occur at some positive altitude, but I don't think that will be the case.
     
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