Silentpoet Posted July 12, 2018 Share Posted July 12, 2018 I was looking for pictures for the random post thread when I came across an interesting question. It is a variation on the treadmill question almost. But with a car and a windmill. 3 Link to comment Share on other sites More sharing options...
Someday Posted July 12, 2018 Share Posted July 12, 2018 Good question. Along the same lines, can you install solar panels on the top of your TESLA and drive for ever? Link to comment Share on other sites More sharing options...
crockett Posted July 12, 2018 Share Posted July 12, 2018 (edited) Nice perpetuum mobile, OP. 19 minutes ago, Someday said: Good question. Along the same lines, can you install solar panels on the top of your TESLA and drive for ever? Not the same, does exists, but not from Tesla (way too heavy). Edited July 12, 2018 by crockett 2 Link to comment Share on other sites More sharing options...
Administrators Rabbi Posted July 12, 2018 Administrators Share Posted July 12, 2018 Nope. Entropy always wins. The parasitic drag of having to use energy to move the windmill will be greater than the power the windmill produces. As a tangent, the surface area of a car is not large enough to power it by solar panels. It would barely even increase range. What it could do is charge the batteries when the car is parked. Most people do not realize how little power solar can produce. Gas is a very energy dense material. Look at it this way. Take a single gallon of gas. Now look at a car. It will move that car 20-40ish miles at 70 miles per hour. If you covered a car with solar panels it would take a day to get a charge to do that. 6 1 Link to comment Share on other sites More sharing options...
Airmotive Posted July 12, 2018 Share Posted July 12, 2018 (edited) Rabbi...making millennials cry since 2001. But, but , but.....what if I really, REALLY feel the fan/wind-powered car will work. Surely my feelings are more powerful than entropy! I mean, like, whoever heard of entropy anyway? But we all know feelings are real. If you feel it, you can dream it! And if you dream it and then smoke a lot of weed, it’s real! #entropyisracist Edited July 12, 2018 by Airmotive 5 1 Link to comment Share on other sites More sharing options...
SC Tiger Posted July 12, 2018 Share Posted July 12, 2018 (edited) 13 hours ago, Silentpoet said: I was looking for pictures for the random post thread when I came across an interesting question. It is a variation on the treadmill question almost. But with a car and a windmill. Negative. Output = Input - loss, and loss is always positive (in the equation). So there is loss somewhere due to drag, friction, resistance, etc. I have heard of air-driven alternators but I don't know how effective they are on a car going 60 mph. The example I am familiar with was on a race car topping 200 (Smokey Yunick). 11 hours ago, Rabbi said: Nope. Entropy always wins. The parasitic drag of having to use energy to move the windmill will be greater than the power the windmill produces. As a tangent, the surface area of a car is not large enough to power it by solar panels. It would barely even increase range. What it could do is charge the batteries when the car is parked. Most people do not realize how little power solar can produce. Gas is a very energy dense material. Look at it this way. Take a single gallon of gas. Now look at a car. It will move that car 20-40ish miles at 70 miles per hour. If you covered a car with solar panels it would take a day to get a charge to do that. Interesting on solar panels. I knew they couldn't power a car completely but I didn't know they were THAT far off. How close to the theoretical limit are we regarding solar panel efficiency, do you think? Edited July 12, 2018 by SC Tiger 1 Link to comment Share on other sites More sharing options...
PNWguy Posted July 12, 2018 Share Posted July 12, 2018 I would be interested in knowing if the limit on solar power efficiency is technological or if there is just a finite amount of energy to be had from the sun's rays. Link to comment Share on other sites More sharing options...
Al Czervik Posted July 12, 2018 Share Posted July 12, 2018 8 hours ago, Rabbi said: the parasitic drag More specifically......anyone.....class....anyone? ? Link to comment Share on other sites More sharing options...
Glocks4Freedom Posted July 12, 2018 Share Posted July 12, 2018 9 hours ago, Rabbi said: Entropy always wins. Entropy is a bitch! No way around it. Link to comment Share on other sites More sharing options...
XSIV4S Posted July 12, 2018 Share Posted July 12, 2018 9 hours ago, Rabbi said: Nope. Entropy always wins. The parasitic drag of having to use energy to move the windmill will be greater than the power the windmill produces. As a tangent, the surface area of a car is not large enough to power it by solar panels. It would barely even increase range. What it could do is charge the batteries when the car is parked. Most people do not realize how little power solar can produce. Gas is a very energy dense material. Look at it this way. Take a single gallon of gas. Now look at a car. It will move that car 20-40ish miles at 70 miles per hour. If you covered a car with solar panels it would take a day to get a charge to do that. You might be the guy to ask. When you overcharge a battery it cooks off the water out of the electrolyte mixture producing hydrogen and oxygen (Occasionally causing a battery to explode when the water gets below the plate level and a dendrite short cooks off). Due to the combustible nature of the hydrogen and oxygen gas mixture, Since water is cheap, I wonder if the energy density of the water is great enough to overcome the charging required to cook it off (would there be an energy surplus)? Link to comment Share on other sites More sharing options...
Administrators Rabbi Posted July 12, 2018 Administrators Share Posted July 12, 2018 2 hours ago, PNWguy said: I would be interested in knowing if the limit on solar power efficiency is technological or if there is just a finite amount of energy to be had from the sun's rays. There is a finite amount of solar energy hitting the panel. It isn’t much. Link to comment Share on other sites More sharing options...
Administrators Rabbi Posted July 12, 2018 Administrators Share Posted July 12, 2018 1 hour ago, XSIV4S said: You might be the guy to ask. When you overcharge a battery it cooks off the water out of the electrolyte mixture producing hydrogen and oxygen (Occasionally causing a battery to explode when the water gets below the plate level and a dendrite short cooks off). Due to the combustible nature of the hydrogen and oxygen gas mixture, Since water is cheap, I wonder if the energy density of the water is great enough to overcome the charging required to cook it off (would there be an energy surplus)? Nope. It does not matter the form of energy (chemical, electrical, nuclear...) entropy always wins. 1 Link to comment Share on other sites More sharing options...
Administrators Eric Posted July 12, 2018 Administrators Share Posted July 12, 2018 What if we cover Millennials in solar cells. Would we get perpetual whining? 3 3 Link to comment Share on other sites More sharing options...
Administrators Eric Posted July 12, 2018 Administrators Share Posted July 12, 2018 Or we could strap them to windmills and Don Quixote their asses. 1 Link to comment Share on other sites More sharing options...
Glocks4Freedom Posted July 12, 2018 Share Posted July 12, 2018 5 minutes ago, Rabbi said: Nope. It does not matter the form of energy (chemical, electrical, nuclear...) entropy always wins. 1 Link to comment Share on other sites More sharing options...
Glocks4Freedom Posted July 12, 2018 Share Posted July 12, 2018 4 minutes ago, Eric said: Or we could strap them to windmills and Don Quixote their asses. 'the Hell do you mean? Link to comment Share on other sites More sharing options...
Administrators Eric Posted July 12, 2018 Administrators Share Posted July 12, 2018 1 minute ago, Glocks4Freedom said: 'the Hell do you mean? I'm talking about tilting at some windbags. Yeah. Link to comment Share on other sites More sharing options...
janice6 Posted July 12, 2018 Share Posted July 12, 2018 (edited) The amount of sunlight at the earth's surface is roughly 1100 W/meter ^2, when the sun is at Zenith. The maximum efficiency of the best Solar Cell to date is 44%. But, cell efficiency for quasi-mono-Si is a record 19.9%. So ~20% of 1100 = 220 W/meter ^2. There are ~ 746 Watts/ Horsepower. So one square meter of Solar panels at 20% efficiency, generating 220 Watts/meter^2 may produce 0.3 Horse Power. To Maintain a speed on the road, just to maintain the speed while overcoming rolling friction and air drag, it is approximately 20 HP. Assuming: a conversion efficiency of around 30% for Gasoline. So you would need roughly 67 meters^2 if solar cell surface to simply keep a constant speed. That's about 6' x 11' of solar cells. This does not consider getting up to that speed! I pulled these approximations from many sources on the Internet. But they are good for a rough result, assuming I didn't make any stupid arithmetic errors. Compared to this solar car, the results are reasonable: Edited July 12, 2018 by janice6 1 1 Link to comment Share on other sites More sharing options...
Glocks4Freedom Posted July 12, 2018 Share Posted July 12, 2018 Long story short: Let's keep on digging and push them rat rods to the limit 2 Link to comment Share on other sites More sharing options...
SC Tiger Posted July 12, 2018 Share Posted July 12, 2018 21 minutes ago, Eric said: What if we cover Millennials in solar cells. Would we get perpetual whining? Only if you fail to cover their mouths. 16 minutes ago, Glocks4Freedom said: PLEASE!!!! Thermo about ran me crazy in college. Link to comment Share on other sites More sharing options...
SC Tiger Posted July 12, 2018 Share Posted July 12, 2018 11 hours ago, Rabbi said: Gas is a very energy dense material. Look at it this way. Take a single gallon of gas. Now look at a car. It will move that car 20-40ish miles at 70 miles per hour. If you covered a car with solar panels it would take a day to get a charge to do that. Consider also that, at present, we are using about 25% of the energy in the gasoline to actually move the car. If we could get that figure up to even 50%....... 1 Link to comment Share on other sites More sharing options...
Administrators Rabbi Posted July 12, 2018 Administrators Share Posted July 12, 2018 7 minutes ago, janice6 said: The amount of sunlight at the earth's surface is roughly 1100 W/meter ^2, when the sun is at Zenith. The maximum efficiency of the best Solar Cell to date is 44%. But, cell efficiency for quasi-mono-Si is a record 19.9%. So ~20% of 1100 = 220 W/meter ^2. There are ~ 746 Watts/ Horsepower. So one square meter of Solar panels at 20% efficiency, generating 220 Watts/meter^2 may produce 0.3 Horse Power. To Maintain a speed on the road, just to maintain the speed while overcoming rolling friction and air drag, it is approximately 20 HP. Assuming: a conversion efficiency of around 30% for Gasoline. So you would need roughly 67 meters^2 if solar cell surface to simply keep a constant speed. That's about 6' x 11' of solar cells. This does not consider getting up to that speed! I pulled these approximations from many sources on the Internet. But they are good for a rough result, assuming I didn't make any stupid arithmetic errors. Compared to this solar car, the results are reasonable: The problem with that is you will never get there in the real world. In the real world there are clouds, night, various atmospheric conditions and the sun hits the surface at its peak only for a moment as the earth turns. For the most part, solar needs storage. So that all the time it is not being used it can “catch up” by storing energy for when a use arises. That at is what gas is. Stored solar energy. 3 Link to comment Share on other sites More sharing options...
Administrators Rabbi Posted July 12, 2018 Administrators Share Posted July 12, 2018 25 minutes ago, Eric said: What if we cover Millennials in solar cells. Would we get perpetual whining? I laughed. That is funny. 1 Link to comment Share on other sites More sharing options...
Glocks4Freedom Posted July 12, 2018 Share Posted July 12, 2018 2 minutes ago, Rabbi said: That at is what gas is. Stored solar energy. That is, until a Democrat Minivan driver..., you know. Link to comment Share on other sites More sharing options...
crockett Posted July 12, 2018 Share Posted July 12, 2018 You can even fly with solar energy alone. Batteries being charged at day time for night flight. This one circumnavigated earth in 6 legs. Anyways, this is and will be commercially infeasible. Link to comment Share on other sites More sharing options...
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