12 ms·
I'm not sure the author realized this, but they're actually making a statement about how crazy exponential growth is. Not about the sustainability of tidal powe
by wcoenen 3y ago
I'm not sure the author realized this, but they're actually making a statement about how crazy exponential growth is. Not about the sustainability of tidal power. This becomes obvious once you look closer at what that 2% growth rate (as assumed in the post) implies.
Our global energy consumption in 2008 was estimated to be 474 exajoules. The total energy received by the earth from the sun during a year is about 5 million exajoules, a fraction of which reaches the surface. 5 million is much more than 474. But at a seemingly modest 2% per year growth rate (as it was between 1980 and 2006), our energy consumption will match those 5 million exajoules in less than 500 years!
Think about that: if energy consumption growth continues at the current pace, then in 500 years we'll either be using ALL solar energy received by the earth (leaving none for the biosphere), or we'll have figured out some magic technology to produce 5 million exajoules of energy per year. Assuming the magic technology, where are we going to get rid of all that extra heat? It would effectively be like having a second sun on earth, cooking us in place.
edit: I copied the numbers above from a post I wrote in 2010, so it may be a bit out of date. But Sabine Hossenfelder recently made a video where she talked about a similar timescale, i.e. boiling oceans in 400 years: https://www.youtube.com/watch?v=9vRtA7STvH4 https://www.youtube.com/watch?v=9vRtA7STvH4
- hkt 3y agoWe, or those of us who by chance survive the worst case scenarios, will just end up learning that maybe huge amounts of socially useless investment isn't compatible with life on earth. It is just not possible unless we carefully plan and ration energy - something the market simply won't do.
- PUSH_AX 3y agoIsn't it more likely that demand will just outgrow supply? Energy poverty seems like a classic "planet Earth" kind of thing.
- azernik 3y agoEven more likely is that, as we're already seeing in rich countries, demand does not continue to grow exponentially and economic growth mostly happens in non-energy-intensive sectors.
- thewakalix 3y agoIf we're still around in 500 years and producing that much energy, I don't expect we'd be limited to Earth anymore!
- deleted 3y ago[deleted]
- gcanyon 3y ago“the rotation of the Earth would lock to the Moon in about 1000 years.” — based on unlimited exponential growth. That’s not worthy of a high school term paper, let alone the work of a PhD. Thanks for saving me the read.
- WillPostForFood 3y agoAny sort of straight line extrapolation is useless. Look at the US energy consumed per capita, flat or declining for the last 50 years. Other parts of the world will follow as they develop. Likely the same for population growth. http://insideenergy.org/wp-content/uploads//2017/01/historical-energy-consumption-large.jpg http://insideenergy.org/wp-content/uploads//2017/01/historic... from: https://insideenergy.org/2017/01/12/energy-explained/ https://insideenergy.org/2017/01/12/energy-explained/
- eldaisfish 3y agothe rest of the world still has to catch up to these levels. Granted, they won't get to the absurd wastage levels of north america but they will continue to consume more energy. Just looking at the energy levels in one country doesn't tell you much.
- giantrobot 3y agoDeveloping countries will increase their energy usage but have the benefit of buying things from developed countries. As we've seen developing countries today have been able to jump right to modern technology for infrastructure. They didn't need to build massive lines of analog telecommunications, they just jumped right to cellular and satellite technology. They can jump right to solar and other renewables as they electrify. They can skip incandescent lighting and go right to LEDs.
- deleted 3y ago[deleted]
- wmf 3y agoThis doesn't help much on the demand side but it will help if they go straight to clean energy.
- giantrobot 3y agoThe availability modern high tech items does help on the demand side. With LED lights a house, office, or school can be lit for a few tens of watts. Modern climate control can heat and cool buildings more efficiently than 40 years ago. Jumping to 3-5G cellular gets telecom for a fraction of the energy or resource investment of wired telecom while still providing high performance. Modern medicine reduces infant and maternal mortality and leads to lower birth rates.
- rich_sasha 3y ago> Our global energy consumption in 2008 was estimated to be 474 exajoules. If my maths is right, that's about 40,000 kcal per person per day, or about 15 times the energy consumption of an average adult. I'm trying to figure out if that's a lot or not. On the one hand, not: this ratio is not strictly bounded in any way, and the human energy consumption is an arbitrary denominator. Still, a very rough interpretation is to say, we consume daily, on average, the fruit of work of 15 people. Of course, that is very skewed. I wonder what the ratio looks like for an average American or European - must be much more. It goes to show what a gilded life we live (on average!!!). Before industrial revolution, all energy basically was muscle power, and it's like for every 1 person alive, we have 15 servants turning the generator for us. I suppose some of this number is literal service providers, fed by food produced by powered agriculture. Is there a logical upper bound to this number? Is there some energy amount we can't use given sufficient supply? Ultimately, all energy we produce is spent on humans so our energy consumption is a yardstick for human energy needs. But that's not quite right either; a lot of energy is wasted. I wonder how much of this number is clothes that go straight from factory to landfill, AC left overnight, inefficient engines and energy storage. I don't really have a point, other than I think this is an interesting fraction to look at.
- messe 3y ago> If my maths is right, that's about 40,000 kcal per person per day, or about 15 times the energy consumption of an average adult. As someone with a physics background... well... it's within an order of magnitude or two, so that sounds close enough to be probably accurate.
- gus_massa 3y agoIt's an interesting comparison. I got some numbers form a random result in google: http://www.ejolt.org/2012/12/human-energy-use-endosomatic-exosomatic/ http://www.ejolt.org/2012/12/human-energy-use-endosomatic-ex... Endosomatic energy (i.e. food): 3.5GJ/year/person Exosomatically energy (i.e. firewood, electricity, solar, fossil fuel, whatever): hunter-gatherers: 20 GJ/year/person (i.e. x6) agriculturalists using animals: 60 GJ/year/person (i.e. x17) industrial society: 200–300 GJ/year/person (i.e. x57-x86)
- deleted 3y ago
- Nition 3y agoHumanity needing that amount of energy seems obviously absurd, but then I suppose a CPU with 100 billion transistors seemed clearly impossible in 1960. Maybe a few hundred years from now, Internet archaeologists will find your comment as one of the first harbingers of the coming World Energy Crisis, much as we see the 1912 Rodney & Otamatea Times "Coal Consumption Affecting Climate" snippet today.[0] Then they'll find this comment... ---- [0] https://paperspast.natlib.govt.nz/newspapers/rodney-and-otamatea-times-waitemata-and-kaipara-gazette/1912/08/14/7 https://paperspast.natlib.govt.nz/newspapers/rodney-and-otam...
- mNovak 3y agoA direct link to the mentioned snippet: https://paperspast.natlib.govt.nz/newspapers/ROTWKG19120814.2.56.5 https://paperspast.natlib.govt.nz/newspapers/ROTWKG19120814....
- littlestymaar 3y ago> one of the first harbingers of the coming World Energy Crisis, It's been well known since at least The limits to growth[1], 51 years ago. [1]: https://en.wikipedia.org/wiki/The_Limits_to_Growth https://en.wikipedia.org/wiki/The_Limits_to_Growth
- hgsgm 3y ago250 years https://en.m.wikipedia.org/wiki/Thomas_Robert_Malthus https://en.m.wikipedia.org/wiki/Thomas_Robert_Malthus
- frind 3y agoIt is interesting to see how little humanity has advanced in the last century. Still unable to keep from being wildy optomistic, pessimistic, and absolutely sure their predictions about the future are going to be more correct than those in the past about the present that they know are proved wrong. If only collective intelligence could rise above it all we might be well on the way to enjoying the creation of a more efficient, less wasteful, and more worthwhile future. . . but that too mentally taxing to engage with. . .so it goes
- 3y ago
- detourdog 3y agoI think the next step is to figure how many exajoules goes to waste heat.
- Baeocystin 3y agoMinus the tiny fraction embodied in global temperature increases, all of it. It's the same reason that the Earth radiates exactly as much energy as it receives from the sun, just a larger number of lower energy, higher entropy photons. What the sun really provides is a source of low entropy.
- detourdog 3y agoWouldn't the earth actually release more energy than it absorbs? My thinking is that the energy that got absorb in other processes such a photosynthesis is a delayed release. The energy released must have some time delay. Maybe it all averages out overtime. Difficult problem I wonder if it is worth answering.
- Baeocystin 3y agoWell, if we wanted to really get in to the details, the Earth is releasing more energy than it receives from the sun simply because it is also cooling. The core grows by about a few mm a year because of this, IIRC. With a brief, 60 million year time frame exception during the Carboniferous, though, the energy stored in life processes is a wash. Assembly and decay are a net balance, and life itself is a strong driver of entropy, so I wouldn't be surprised at all if, on the whole, the biosphere is a net energy sink.
- detourdog 3y ago>>Well, if we wanted to really get in to the details, Of course we want to get into the details. I can see there are many reasons why the earth maybe releasing more than it absorbs.
- 3y ago
- deleted 3y ago[deleted]
- gnfargbl 3y agoHuman energy use isn't going to continue to grow exponentially for the next 500 years. The world population is predicted to peak about 30% above where it is now and then fall back -- maybe to 7 billion people sustained. We seem to need about 200 GJ per person to be really happy [1], so let's assume 300 GJ per person. We should be able to get by, happily, on 2000 EJ per year sustained. By your figures, that's less than 1% of what the sun provides. [1] https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3978 https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2...
- deleted 3y ago[deleted]
- littlestymaar 3y ago> We should be able to get by, happily, on 2000 EJ per year sustained. By your figures, that's less than 1% of what the sun provides. Then at that rate we'd have 100,000 years of Tidal energy available even if we used it for the totality of our energy needs (and 10,000,000 years if we use it for 1% of our needs as taken in the paper). And that was basically the point of the person you're responding to: it's not so much that tidal energy is non-renewable, the problem is that the paper assume exponential consumption growth, and exponential growth is unsustainable no matter what.
- dduugg 3y agoWhat's the theoretical max energy for other sources of energy, such as nuclear (fission) power?
- sjducb 3y agoI think we’ll have colonized space by then, maybe even starting to build a Dyson sphere.
- cornel_io 3y agoI was super skeptical of this article, because I was trying to imagine how we'd have to arrange extractors in the oceans to pull any meaningful amount of energy out of the rotation of the earth based on tides, and only at the end of the article did I see that assumption of 2% compounding multiplied out as far as needed...ugh. The implausibly is staggering, we'd run out of resources to build extractors way before causing any meaningful shift in the rotation: if the monstrous land barriers of the continents take millions of years to drain a small percentage of the energy, we have zero hope of achieving much more with the solid mass available to us on Earth, short of a Dyson sphere-level breakthrough in "moving mass around", oh, and by the way it has to happen deep underwater as well, and we need to channel all the energy somewhere useful! Way harder than just making a ginormous but thin solar array in space, which is almost certainly what we'd do instead from a "energy cost to arrange matter" optimization POV.
- arnaudsm 3y agoYour idea sounds similar to the Kardashev scale [1], and we seem to be at 0.733. The concept of the Dyson sphere emerged from that theory. [1] https://en.wikipedia.org/wiki/Kardashev_scale https://en.wikipedia.org/wiki/Kardashev_scale
- graypegg 3y agoWouldn't energy available to be consumed become a limiting factor in our rate of using that energy?
- giantg2 3y ago"Think about that: if energy consumption growth continues at the current pace, then in 500 years we'll either be using ALL solar energy received by the earth (leaving none for the biosphere), or we'll have figured out some magic technology to produce 5 million exajoules of energy per year." So nuclear?
- deleted 3y ago[deleted]
- empath75 3y agoWhile this is true, a lot of economists build their models assuming unlimited exponential growth. It does seem that we're going to hit a brick wall in growth in a few hundred years if that doesn't stop. There seems to be some idea that we can continue exponential growth if we can just figure out renewable energy and we can't. There is _no such thing_ as renewable energy in a regime with unlimited exponential economic growth.
- Aerroon 3y agoEconomic growth doesn't necessarily require energy expenditure growth. Figuring out how to do something more efficiently (for half the energy) is also economic growth.
- golem14 3y agoI found the Hans Rosling series of talks quite good and a bit reassuring. If we survive the next 100 years, we'll probably do OK for a while longer.
- deleted 3y ago[deleted]
- uoaei 3y agoSci-fi idea: binary star system is really the remnants of an advanced civilization, originally orbiting a single (much larger) star on their own planet, that collapsed in on itself from the consequences of its energy generation technology.
- Aerroon 3y agoTo extrapolate further on the silliness of 2% growth. Let's convert the entire Earth into pure energy: Earth's mass is 10^24 kg. E_earth = mc^2 = 9 * 10^40 J E_current * 1.02^x = E_earth 474 * 10^18 * 1.02^x = 9 * 10^40 x = 2357.91 years At a modest 2% growth we would be using up the entire Earth's mass in energy per year in only 2358 years.
- cryptonector 3y agoHuman population growth is set to reach a peak in just two+ decades, and then will start declining for some time. Where we've seen fertility drop below replacement rate we've also seen that drop be persistent for decades, which means that population declines will accelerate before they arrest (if they arrest). So this is a bit of much ado about nothing. We're not going to exceed low single digits percentage points of the energy reaching the planet from the Sun. Heat dissipation is relatively easy if we use 1% equivalent of Solar energy on Earth: the water cycle can speed up in response to positive forcings and slow down in response to negative forcings. This is why the planet's climate has been so stable in the sense of being a random walk centered on an optimum that supports the sort of life that we have on the planet. Similar observations explain Mars' and Venus' inhospitability: there's not enough atmosphere, much less liquid water on Mars to drive a similar thermostatic system, while Venus' climate is pegged at a maximum, with albedo as high as it can reasonably go, and it can't cool itself significantly with anything like a water cycle.
- f33d5173 3y agoSuppose we put solar panels in space. Then we would be entirely unconstrained by the amount of energy received by the earth. Heat dissipation would also no longer affect earth. Given our current trajectory with regards to spaceflight, it seems plausible we will be doing large projects of that scale in space in say 300 years, enough time to meet such exponential growth targets.
- wcoenen 3y agoGoing to space still cannot outrun an exponential function. Extrapolating exponential growth always leads to catastrophe. Imagine the sphere of a civilization expanding in space at some speed, in all directions. The volume of this sphere would equal time cubed (t^3) times some constant. Now suppose this civilization has a magical power source that allows them to keep growing power consumption exponentially. So power consumption would equal 2^t (where time unit = one doubling time, 35 years in the case of 2% growth) times some constant. 2^t will always overtake t^3 no matter the constants, so power density of the sphere trends to infinity, so the civilization will cook itself in waste heat.
- deleted 3y ago[deleted]