Comments by "seneca983" (@seneca983) on "Engineering with Rosie" channel.

  1. Could they also recycle other types of fiber composites like basalt or carbon fiber composites?
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  2. Road dimensions don't (often) matter for offshore wind. Ships can be very big.
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  3. I'm guessing such a hoist wouldn't see much use making it uneconomical.
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  4.  @ReevansElectro  It's possible that I'm wrong but I think it's more likely there's a good reason why engineers haven't chosen to do what you're suggesting here. You asked, "Why aren't windmills designed with their own winch". I gave my answer to that (though admittedly it's somewhat of a guess since I'm not a wind turbine engineer).
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  5.  @acmefixer1  "There is a correlation between nuclear power plants and nuclear weapons." But I think if there's causation it's not: nuclear plants -> nuclear weapons. It's far more likely that it's: nuclear weapons -> nuclear plants.
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  6. "Much better to remove the ironmaking process and concentrate on electrical based steelmaking i.e. scrap." Recycling scrap steel obviously makes sense but it's likely not enough. We'll need new steel as well and it would be better if we could do that without using carbon as a reducing agent.
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  7. About the screw analogy, I think a ship's propeller can also be called a "screw".
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  8.  @ReevansElectro  I'm a bit skeptical of it being cheaper. Also, the hub needs to be lifted on top of the tower. I don't see how you could easily do that with a winch that's not somehow above the tower.
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  9.  @Nerd3927  That's not a realistic worry. Heat engines cannot reduce their waste heat below the Carnot limit.
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  10. If they're not reused this way they still need to be transported to a landfill, a cement kiln, or some other kind of facility because they usually can't just be buried onsite. It's not obvious that transporting them to some location to form a bridge etc. would be worse.
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  11.  @greatbriton8425  "the instant the cart goes faster than the wind, the wind is no longer pushing it. No energy is being input into the system." There's still energy being input into the system. Even though the cart is going faster than the wind the propeller is spinning fast enough that overall the cart is slowing wind down behind it rather than accelerating it. This is where the energy is extracted from.
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  12.  @acmefixer1  You can't build them fast enough. They should be ready already this year. I don't think there is an alternative to lignite on the short term. (Note that I'm specifically talking about the potential acute crisis that may come from the unreliability of Russian gas deliveries during the Ukraine war. I'm not talking about the longer term.)
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  13. One point to add is that not only are winds winds stronger at higher altitudes but also more consistent which is important because the intermittent nature of wind energy is probably its biggest downside.
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  14.  @latemnetlom  "includes the heat of condensation of the product water once you burn the H2" But I got the impression that the current use for the hydrogen they produce isn't mostly for burning or fuel cells.
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  15. My first thought about that is that for a given tower height one big turbine can sweep a larger area than several smaller ones in one tower. However, I'm not an engineer so I'm not sure if that's enough to kill the multi-rotor designs.
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  16.  @gregsomlai297  No, it can go faster than the wind consistently.
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  17.  @sebastjansslavitis3898  "its not the direction wind would spin it" The wind is not directly spinning it. It's being spun by the wheels to such direction that it generates thrust.
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  18. You can also use composite tanks. I'd assume they're less susceptible to embrittlement (though leakage is still going to happen).
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  19.  @ReevansElectro  I mean, it's not enough to slap a winch on top of the tower (sans hub). You'd need some structure on top of the tower holding the winch so that it's above the top of the tower by enough that the hub fits under it. Otherwise, it won't be able to lift the hub all the way. Such a structure doesn't sound cheap enough to be more economical than just using a mobile crane. But I thought of a bigger problem. The tower is often made of several sections which are lifted on top of each other with a crane. Since you need a crane for them, might as well use it for the hub too. Using an integrated winch for them sounds even more difficult.
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  20. It shouldn't matter as long as the cart isn't turning.
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  21.  @danwylie-sears1134  One solution could be to give the numbers assuming a few different interest rates. In any case, you have to use some kind of (real) positive rate because time-value is a thing.
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  22. "what is the equilibrium condition for blackbird?" There's no simple formula. It depends on the losses in the transmission and the drag on its frame.
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  23.  @deadeye_john  Surely superglue isn't immune to fatigue either.
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  24.  @deadeye_john  Fatigue means that the material slowly becomes full of microcracks too tiny to see with the naked eye. I don't see how you could inject glue into those.
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  25. For a vehicle going against the wind that could work.
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  26.  @Ikbeneengeit  "the Netherlands could use imported green hydrogen from North Africa for district heating and electricity" I don't see how that would make sense. If the hydrogen is made with electrolysis, then surely it makes more sense to just import the electricity directly rather than turn it into hydrogen and back with considerable loss at both steps. If it is made from natural gas, then likely it makes more sense to just use the natural gas for energy directly.
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  27.  @Ikbeneengeit  Morocco is already in the same synchronized grid as continental Europe. Also, a hydrogen pipeline would be a much larger project.
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  28. Am I seeing wrong or is the pre-bend towards the tower rather than away from it?
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  29. "I couldn't understand why someone was just throwing away money on such a large scale." Utilizing it might not be that cheap either. Of course, I'm just guessing here.
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  30.  @jimurrata6785  It seems even extending the use of their 3 remaining reactors is politically impossible let alone re-starting any of the already closed ones. Thus it seems there isn't a good alternative to lignite.
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  31. "96% of mammals are livestock and human by weight" That's probably land mammals, not all mammals.
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  32. Wind is required. If there's no wind then consider the inertial frame tied to the ground (and the stationary air). In that frame both the cart and the air would be accelerated if the propeller pushed the cart forward so then an energy source would be required.
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  33.  @malingeorgiev2962  "We have initially still car and no wind at all. We push the car to certain speed. Can the thrust be bigger or equal to the drug." No, it is essential that the air is moving relative to the ground or else the cart cannot extract energy from the air to accelerate.
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  34.  @UnwittingSweater  One issue that comes to mind is that for a given tower height one big turbine can sweep a larger area than several smaller turbines in one tower. However, I'm not an engineer so I don't know if that's enough to kill multi-rotor designs.
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  35. You're confusing different things. 10 m/s is the wind speed relative to the ground and 2 m/s is relative to the cart.
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  36.  @millomweb  Not all of those listed speeds were supposed to be relative to the cart.
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  37. When going against the wind it needs to work in reverse with the turbine/propeller turning the wheels rather than the other way around as done here.
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  38.  @MitkoGorgiev  "how the cart is moving BEFORE (I repeat BEFORE) it reaches the wind speed" At first the wind can accelerate the cart because the frame of the cart has some drag. Once it's moving the propeller starts accelerating it too, both before and after exceeding wind speed. "If the wheels are moving the propeller, then the cart could also move in a still atmosphere provided we give it an initial velocity. Then it will move forever." Not at all. The relative movement of the air and ground is crucial. Without it there's no energy source.
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  39. No, at least if you assume uniform wind. You can look at that kind of situation in the inertial frame tied to the air. In that frame the air is stationary and there's no wind to power any vehicle. The car can only work because the air is moving relative to the ground and the car is touching both.
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  40. Cathode is negative.
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  41.  @electrodacus  This is not a case of stored energy. In principle, the cart can maintain a speed above the winds speed indefinitely as long as the wind is blowing.
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  42.  @electrodacus  "Is there a designed speed above wind speed that the vehicle will reach and then stay in equilibrium at that speed indefinitely ?" At some point drag will exceed the thrust that can be generated if the vehicle doesn't topple over before that. Of course, such limit is probably not explicitly designed. "How do you capture the wind energy when as far as the vehicle is concerned when you are traveling at say 2x wind speed the vehicle will now experience a head wind." It's because the propeller spins fast enough to generate thrust. The wind is still essential because the apparent headwind is slower than the speed of the ground relative to the vehicle. That's why the wheels can power the propeller. "If you take 5W from the wheel and put 4W out of propeller will the vehicle not slow down ?" No, because the force at the propeller is greater than the one at the wheels. "You can not say that 1W delta comes from the wind as air particles are now traveling in the opposite of vehicle direction at 2x the wind speed slowing the vehicle even more." You're looking at the inertial frame tied to the vehicle (at a particular moment)? I don't think it's the most intuitive frame to look at this. However, if you want to consider this frame, notice that here the ground contains kinetic energy because it's moving relative to the vehicle. So basically in it's own frame the vehicle will decelerate the ground and accelerate the air. Because the ground is moving faster than the air the former will release more energy than the latter consumes. The difference (minus some dissipative losses like friction) can be used to accelerate the vehicle.
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  43. About the Betz limit. My intuition would say that a VAWT can extract energy from the wind two times at most (on the upwind side and on the downwind side) and therefore applying the Betz limit should give a theoretical maximum. The Betz limit is 16/27 or about 59%. The Betz limit applied twice is 1-(1-16/27)²=608/729 or about 83%. Does this make any sense or am I on a completely wrong track?
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  44. I suspect that the circuitries for laptop batteries don't facilitate discharging it through the charging port.
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  45.  @sp90009  "Somebody thought about this use case during the design phase?" Based on the Wikipedia page on vehicle-to-grid technology most EVs don't have that capability though some do. The page says: "There are several electric vehicles that have been specially modified or are designed to be compatible with V2G. Hyundai ix35 FCEV from Delft University of Technology is modified with a 10 kW DC V2G output. Two vehicles that have a theoretical V2G capability include the Nissan Leaf and Nissan e-NV200."
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  46.  @sp90009  Redesign for future EV production is probably a minor issue since it's a fairly small part of the car. Retrofits on existing EVs are probably a bit more difficult but can probably be done as well. I suspect laptop batteries aren't big enough to economically justify a grid monitoring device for them.
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  47.  @roberthigbee3260  "on a windless day, if you towed that fancy prop-car behind a pickup truck, the prop-car would soon go faster than and then pass the pickup truck and keep on going" No, that would be true free energy. This cart is getting kinetic energy from the wind.
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  48. There's a similar waste-to-energy plant in Vantaa, Finland. According to their website, they clean the exhaust with electrostatic filters, activated carbon, and lime.
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  49. The energy is coming from the wind.
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  50.  @sebastjansslavitis3898  If the propeller were to spin in the opposite direction it would slow down the cart. It is the right direction. Consider the inertial frame tied to the ground. In that frame the wind gets decelerated by the propelled behind the cart so the air is losing kinetic energy and the cart is gaining some.
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