4 ms·

Think of it this way... the Earth is a rock ~4K miles in radius. Essentially all of it is molten rock. When people try hard we can melt rocks to make metals.

by adekok 9y ago

Think of it this way... the Earth is a rock ~4K miles in radius. Essentially all of it is molten rock. When people try hard we can melt rocks to make metals. But we need special-built furnaces, machines, etc. And these furnaces are maybe 50 feet across. So the Earth has a heat stored which is (4K miles / 50 feet)^3 times larger than a blast furnace. i.e. about 7x10^16 times larger. If everyone on Earth had their own personal blast furnace, we'd be controlling 10 million times less energy than what's in the core of the Earth. Similar calculations apply to other calculations. A Physics 101 calculation I did (years ago) was how much a tidal plant would slow down the rotation of the Earth. The answer was by less than a second a day, after 100 years of running. > ke, what would happen globally if the entire state of Arizona was in the shadow of solar arrays? The plants wouldn't grow. :) But seriously, the energy has to go somewhere. If it's hitting solar panels instead of the ground, the net effect to the world is essentially zero. Maybe locally the ground would be cooler because it's in the shade. But that's about it.

xtreme 9y ago
Less than a second a day in 100 years is a huge change in earth scale. I'm curious, what kind of tidal plant would even come close? Is it assuming we extract 100% energy from the tidal waves and entirely stop the tides, somehow?
- simonh 9y ago
  Doesn't it depend on how much less than a second it is?
- vdnkh 9y ago
  I'm fairly certain stopping the tides would be devastating to the environment since several ecosystems (tidal plains, marshes, riparian zones, etc.) depend upon them.
infinite8s 9y ago
You are thinking in linear terms. Humanity's historical energy use definitely doesn't look linear, more like exponential - https://gailtheactuary.files.wordpress.com/2012/03/world-energy-consumption-by-source.png https://gailtheactuary.files.wordpress.com/2012/03/world-ene... I imagine that if we were able to tap into deep geothermal energy the continuing exponential growth would eventually pass some sort of geothermal limit point.
- foota 9y ago
  This is true, but I know for a fact that US energy use at least has roughly dropped or remained stable for the last decade. Increase in energy use is typically driven by people's increasing incomes and their ability to buy energy for using appliances and such. We can expect energy use to increase significantly globally until everyone is at a base level of income, but after that it should be capped at population growth.
- mirimir 9y ago
  Remember Asimov's city-planet Trantor. It relied in part on geothermal energy (core taps) with huge radiator arrays at the poles.
avar 9y ago
There's no way that a tidal plant running for 100 years is going to change the day by 1 second. You're many orders of magnitudes off. That means that if you built 100 of those plants that in 1 year you'd change the length of the day by 1 second. The 2011 Tōhoku earthquake and tsunami released 3.9×10^22 joules of energy[1] and changed the day by just over a microsecond[2]. A single Tsar Bomba releases 2.1×10^17 joules, so you'd need the energy of around 200 thousand of those to produce the same amount of energy as the earthquake, and then assuming you can direct that energy you need 1000 times more to shift the day by a second instead of a microsecond. That means that each one of your proposed tidal plants would need to generate the energy of 20,000,000 Tsar Bombas per year. That's one Tsar Bomba's worth of energy being released every 1.5 seconds at each one of those 100 plants. Buy stock in sunscreen companies now! Each one of your 100 plants would satisfy all of current yearly world energy production in just 30 minutes[3][4]. I'm too lazy to calculate what that would do to the surrounding area, but I'd wager that they're going to severely depress local property prices due much of the surrounding beach-side property area now being turned into permanent molten lava. The good news is you could probably build really good wind power plants now, due to constant hurricane winds not seen on Earth since the K–T impact, but I digress. I didn't check your molten rock calculation but given how off your tidal plant calculation is I wouldn't be surprised if it's way off as well. 1. https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_and_tsunami#Energy https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an... 2. https://www.nasa.gov/topics/earth/features/japanquake/earth20110314.html https://www.nasa.gov/topics/earth/features/japanquake/earth2... 3. https://en.wikipedia.org/wiki/World_energy_consumption https://en.wikipedia.org/wiki/World_energy_consumption 4. ((5.67x10^20)/(2.1x10^17))/1.5/60 = 30
- skrause 9y ago
  > and then assuming you can direct that energy you need 1000 times more to shift the day by a second instead of a microsecond. Still off by a factor of 1000, a microsecond is one millionth of a second.
  - avar 9y ago
    Yes you're right. I mixed up micro & milli there. So: * [...] 20,000,000,000 Tsar Bombas per year * One Tsar Bomba going off every 1.5ms * World energy production satisfied in 1.8 seconds We're also going to need more sunscreen.

by adekok 9y ago

xtreme 9y ago

Less than a second a day in 100 years is a huge change in earth scale. I'm curious, what kind of tidal plant would even come close? Is it assuming we extract 100% energy from the tidal waves and entirely stop the tides, somehow?

simonh 9y ago
Doesn't it depend on how much less than a second it is?
vdnkh 9y ago
I'm fairly certain stopping the tides would be devastating to the environment since several ecosystems (tidal plains, marshes, riparian zones, etc.) depend upon them.

infinite8s 9y ago

You are thinking in linear terms. Humanity's historical energy use definitely doesn't look linear, more like exponential - https://gailtheactuary.files.wordpress.com/2012/03/world-energy-consumption-by-source.png https://gailtheactuary.files.wordpress.com/2012/03/world-ene... I imagine that if we were able to tap into deep geothermal energy the continuing exponential growth would eventually pass some sort of geothermal limit point.

foota 9y ago
This is true, but I know for a fact that US energy use at least has roughly dropped or remained stable for the last decade. Increase in energy use is typically driven by people's increasing incomes and their ability to buy energy for using appliances and such. We can expect energy use to increase significantly globally until everyone is at a base level of income, but after that it should be capped at population growth.
mirimir 9y ago
Remember Asimov's city-planet Trantor. It relied in part on geothermal energy (core taps) with huge radiator arrays at the poles.

avar 9y ago

There's no way that a tidal plant running for 100 years is going to change the day by 1 second. You're many orders of magnitudes off. That means that if you built 100 of those plants that in 1 year you'd change the length of the day by 1 second. The 2011 Tōhoku earthquake and tsunami released 3.9×10^22 joules of energy[1] and changed the day by just over a microsecond[2]. A single Tsar Bomba releases 2.1×10^17 joules, so you'd need the energy of around 200 thousand of those to produce the same amount of energy as the earthquake, and then assuming you can direct that energy you need 1000 times more to shift the day by a second instead of a microsecond. That means that each one of your proposed tidal plants would need to generate the energy of 20,000,000 Tsar Bombas per year. That's one Tsar Bomba's worth of energy being released every 1.5 seconds at each one of those 100 plants. Buy stock in sunscreen companies now! Each one of your 100 plants would satisfy all of current yearly world energy production in just 30 minutes[3][4]. I'm too lazy to calculate what that would do to the surrounding area, but I'd wager that they're going to severely depress local property prices due much of the surrounding beach-side property area now being turned into permanent molten lava. The good news is you could probably build really good wind power plants now, due to constant hurricane winds not seen on Earth since the K–T impact, but I digress. I didn't check your molten rock calculation but given how off your tidal plant calculation is I wouldn't be surprised if it's way off as well. 1. https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_and_tsunami#Energy https://en.wikipedia.org/wiki/2011_T%C5%8Dhoku_earthquake_an... 2. https://www.nasa.gov/topics/earth/features/japanquake/earth20110314.html https://www.nasa.gov/topics/earth/features/japanquake/earth2... 3. https://en.wikipedia.org/wiki/World_energy_consumption https://en.wikipedia.org/wiki/World_energy_consumption 4. ((5.67x10^20)/(2.1x10^17))/1.5/60 = 30

skrause 9y ago
> and then assuming you can direct that energy you need 1000 times more to shift the day by a second instead of a microsecond. Still off by a factor of 1000, a microsecond is one millionth of a second.
- avar 9y ago
  Yes you're right. I mixed up micro & milli there. So: * [...] 20,000,000,000 Tsar Bombas per year * One Tsar Bomba going off every 1.5ms * World energy production satisfied in 1.8 seconds We're also going to need more sunscreen.