5 ms·

...and "80 million". Fine, let's quadruple consumption – we're good for 20 million years. Ok, okay, let's go to 100x consumption – we're good for 800,000 year

...and "80 million". Fine, let's quadruple consumption – we're good for 20 million years. Ok, okay, let's go to 100x consumption – we're good for 800,000 years. I think we're ok.

dman 10y ago
Can we do the same math for electricity consumption from 100 years ago? :)
- Normal_gaussian 10y ago
  https://ourfiniteworld.com/2012/03/12/world-energy-consumption-since-1820-in-charts/ https://ourfiniteworld.com/2012/03/12/world-energy-consumpti... No idea how good the source is, however it looks like we have a nice exponential there. Lets see what the envelope says for an exponent of 2: Using numbers from parent commentors, log2(6.6 x 10^13) is about 45.9, so we are in our 46th doubling period. A guess on the graph says its 25 years to double. > The total heat content of the Earth is of the order of 12.6 x 10^24 MJ, and that of the crust the order of 5.4 x 10^21 MJ (Dickson and Fanelli, 2004). so that's end of crust energy usefulness at the start of the 72nd period and end of Earth energy less than halfway through the 84th period. So that gives us 500-1000 years of energy from now if we solely use the planets heat. Whether we soley use it or not becomes largely irrelevant due to the exponent, we can stretch it as a major source a few hundred more years or so. Of course, if in 1000 years we aren't only using this planet we should be good. How many years to the next system again?
- iaw 10y ago
  Not a good analogy, 100 years ago not only was the population lower but there was no electrical infrastructure.
  - dman 10y ago
    You are successfully making the point I was trying to. We are willing to concede that usage patters from 100 years ago are unrealistic current realities. However we would simultaneously like to use the current reality to project future realities that are much farther away (in some cases 19 million years away).
    - dpark 10y ago
      It doesn't actually matter much if our usage projections are good. What matters is 1) that the energy store is so massive that it's hard to imagine how we could possibly exhaust it, and 2) the current dominant alternative (i.e. fossil fuel) is known to be terrible for us. If we switched to geothermal and set the world up to end humanity in a thousand years, we'd still be better off than continuing our desperate use of fossil fuels and ending humanity even sooner.
      - jsudhams 10y ago
        The issue is we use up fossil fuels we could still continue for more years, I don't see any reason for it to end much before that. If we make mistake with earth core we would mostly surely setup end of humanity atleast. I would rather focus on getting the world to a place where willno borders and safe religion etc.. which would get lot more runtime for humans than this. If we optimize food production find a better alternative for capatalism we may live better with or with out need for fuel
        dpark 10y ago
        Our food production is driven by fossil fuels. Everything from the farm equipment to the fertilizers we spread to the trucks we ship it in are powered by fossil fuels. When we run out of fossil fuels, we better have a back up energy source (or sources) ready, because our food production will plummet if not. So will basically every industry, since they all depend on cheap transport and automation at this time. So we'll all starve while the economy collapses around us and our infrastructure falls apart as we have neither the money nor the energy supplies to fix it. Yeah, our dependence on fossil fuels is a huge problem, and not just because of climate change (which might also kill us).
    - eggy 10y ago
      I agree somewhat, but even though more devices are electrical or electronic and attached to the grid, they are more efficient. My 42" LED TV is using 95W, less than a 100W light bulb, whereas my old 19" tube color TV in 1978 used more. Mobile phones didn't exist when I was young, and there are certainly a lot of them now even if they are low power devices, so it would be interesting to see electrical usage patterns pre-mobile phones vs. today. The same goes for cars. Cars were using leaded gasoline in the US and getting 8 to 12 mpg, and now 30 to 35 mpg or greater on the highway, but do people drive more frequently, and with single riders? Another question is would any cooling of the total Earth's heat energy be offset by global warming? The thermal differential would be less thereby slowing the migration of heat to the surface?
dsp1234 10y ago
Since the magnetic field of the earth, which protects us from the solar winds among other things, is generated by spinning of the molten outer core, do you happen to know how much of that energy would be available before adverse effects happen? It's obvious that the answer is less than 100%, since a completely solid core would provide no magnetic field. Is there some way to tell whether it's closer to 0.1%, 1% or 10%?
- dpark 10y ago
  Let's assume it's not just 0.1% but 0.001%. That still leaves us a comfortable runway of 19 million years at our current levels. But also let's hope it's not 0.001% because I'm pretty sure the core will cool more than that on its own over a shorter timespan than 19 million years.
  - nitrogen 10y ago
    Won't thorium decay keep it warm for a good long while?
    - dpark 10y ago
      I'm honestly not sure. I don't know how much energy is being created inside the Earth and how much is just residual. It's my understanding that the Earth is slowly cooling, though, so radioactivity isn't replenishing heat as rapidly as we're losing it.
  - drivebyneatfact 10y ago
    Wikipedia suggests cooling of 100 degrees C every billion years. 19 million years is 1.9% of the billion year rate. So it suggests the core should lose 1.9C in 19 million years. That's about 0.035% of the total temp, using Wikipedia's 5700C as the temp estimate. That's a great initial guess, given how much uncertainty is (i've recently heard core temp could be 4x the wiki number, and some people estimate the earth's core only has lost a few degrees since it formed, rather than nearly 500 degrees). Neat stuff, thanks for providing the opportunity to look in to this.
- 10y ago

...and "80 million". Fine, let's quadruple consumption – we're good for 20 million years. Ok, okay, let's go to 100x consumption – we're good for 800,000 years. I think we're ok.

dman 10y ago

Can we do the same math for electricity consumption from 100 years ago? :)

Normal_gaussian 10y ago
https://ourfiniteworld.com/2012/03/12/world-energy-consumption-since-1820-in-charts/ https://ourfiniteworld.com/2012/03/12/world-energy-consumpti... No idea how good the source is, however it looks like we have a nice exponential there. Lets see what the envelope says for an exponent of 2: Using numbers from parent commentors, log2(6.6 x 10^13) is about 45.9, so we are in our 46th doubling period. A guess on the graph says its 25 years to double. > The total heat content of the Earth is of the order of 12.6 x 10^24 MJ, and that of the crust the order of 5.4 x 10^21 MJ (Dickson and Fanelli, 2004). so that's end of crust energy usefulness at the start of the 72nd period and end of Earth energy less than halfway through the 84th period. So that gives us 500-1000 years of energy from now if we solely use the planets heat. Whether we soley use it or not becomes largely irrelevant due to the exponent, we can stretch it as a major source a few hundred more years or so. Of course, if in 1000 years we aren't only using this planet we should be good. How many years to the next system again?
iaw 10y ago
Not a good analogy, 100 years ago not only was the population lower but there was no electrical infrastructure.
- dman 10y ago
  You are successfully making the point I was trying to. We are willing to concede that usage patters from 100 years ago are unrealistic current realities. However we would simultaneously like to use the current reality to project future realities that are much farther away (in some cases 19 million years away).
  - dpark 10y ago
    It doesn't actually matter much if our usage projections are good. What matters is 1) that the energy store is so massive that it's hard to imagine how we could possibly exhaust it, and 2) the current dominant alternative (i.e. fossil fuel) is known to be terrible for us. If we switched to geothermal and set the world up to end humanity in a thousand years, we'd still be better off than continuing our desperate use of fossil fuels and ending humanity even sooner.
    - jsudhams 10y ago
      The issue is we use up fossil fuels we could still continue for more years, I don't see any reason for it to end much before that. If we make mistake with earth core we would mostly surely setup end of humanity atleast. I would rather focus on getting the world to a place where willno borders and safe religion etc.. which would get lot more runtime for humans than this. If we optimize food production find a better alternative for capatalism we may live better with or with out need for fuel
      - dpark 10y ago
        Our food production is driven by fossil fuels. Everything from the farm equipment to the fertilizers we spread to the trucks we ship it in are powered by fossil fuels. When we run out of fossil fuels, we better have a back up energy source (or sources) ready, because our food production will plummet if not. So will basically every industry, since they all depend on cheap transport and automation at this time. So we'll all starve while the economy collapses around us and our infrastructure falls apart as we have neither the money nor the energy supplies to fix it. Yeah, our dependence on fossil fuels is a huge problem, and not just because of climate change (which might also kill us).
  - eggy 10y ago
    I agree somewhat, but even though more devices are electrical or electronic and attached to the grid, they are more efficient. My 42" LED TV is using 95W, less than a 100W light bulb, whereas my old 19" tube color TV in 1978 used more. Mobile phones didn't exist when I was young, and there are certainly a lot of them now even if they are low power devices, so it would be interesting to see electrical usage patterns pre-mobile phones vs. today. The same goes for cars. Cars were using leaded gasoline in the US and getting 8 to 12 mpg, and now 30 to 35 mpg or greater on the highway, but do people drive more frequently, and with single riders? Another question is would any cooling of the total Earth's heat energy be offset by global warming? The thermal differential would be less thereby slowing the migration of heat to the surface?

dsp1234 10y ago

Since the magnetic field of the earth, which protects us from the solar winds among other things, is generated by spinning of the molten outer core, do you happen to know how much of that energy would be available before adverse effects happen? It's obvious that the answer is less than 100%, since a completely solid core would provide no magnetic field. Is there some way to tell whether it's closer to 0.1%, 1% or 10%?

dpark 10y ago
Let's assume it's not just 0.1% but 0.001%. That still leaves us a comfortable runway of 19 million years at our current levels. But also let's hope it's not 0.001% because I'm pretty sure the core will cool more than that on its own over a shorter timespan than 19 million years.
- nitrogen 10y ago
  Won't thorium decay keep it warm for a good long while?
  - dpark 10y ago
    I'm honestly not sure. I don't know how much energy is being created inside the Earth and how much is just residual. It's my understanding that the Earth is slowly cooling, though, so radioactivity isn't replenishing heat as rapidly as we're losing it.
- drivebyneatfact 10y ago
  Wikipedia suggests cooling of 100 degrees C every billion years. 19 million years is 1.9% of the billion year rate. So it suggests the core should lose 1.9C in 19 million years. That's about 0.035% of the total temp, using Wikipedia's 5700C as the temp estimate. That's a great initial guess, given how much uncertainty is (i've recently heard core temp could be 4x the wiki number, and some people estimate the earth's core only has lost a few degrees since it formed, rather than nearly 500 degrees). Neat stuff, thanks for providing the opportunity to look in to this.
10y ago