Hacker News Reader

>Thus, the maximum, long-term sustainable pace of energy consumption is equal to what we can extract from the Sun. And, yet, we consume that much every year by August 1! While the trend has flattened out in recent years, it shows no sign of declining [0].

This is misleading and not what they link supports. The linked calculation is not tied to the possible power extraction from the sun. This estimate is based on CO2 currently produced per person and the earth's ability to sequester the CO2.

Global electricity consumption is is about 2.6 Terrawatts [1]

Global total potential for technically feasible PV solar has been estimated at ~ 613 389 PWh/y or 70 Terawatts [2]

https://en.wikipedia.org/wiki/List_of_countries_by_electrici...

https://www.researchgate.net/publication/292991459_Estimatio...

"Energy from the Sun" is not just "energy from solar power." It includes wind and biomass as well. Biomass is probably the most efficient way to sequester carbon. So, yes, it is accounted for.

Put another way: you can't use fossil fuels to sequester carbon, and nuclear is a drop in the bucket. So, guess where the energy necessary to do it comes from?

I'm not following your rebuttal here. s1artibartfast says that the sun can provide much more power than we currently consume. The limit from your link from earlier is not a limit on how much power the sun can provide, but rather a limit on how much power we can produce before we produce too much CO2. With power production methods that produce less CO2, we won't run into that limit, and we obviously won't run into the solar energy limit.

The average power that the sun shines on the Earth is a huge amount and more than enough to cover all of our current energy needs, even using the technology and efficiency of today, and leaving land for other uses.

You can use solar to reduce or eliminate the carbon emitted. You can use solar electricity to sequester carbon if you want. You could even make oil and pump it back into the ground.

While not readily available everywhere now, there's abundance of geothermal power beneath our feet, and not from the sun either.

>Malthus was right!

Oh no he wasn't in his main hypothesis, roughly what wikipedia has as

>Populations had a tendency to grow until the lower class suffered hardship, want and greater susceptibility to famine and disease, a view that is sometimes referred to as a Malthusian catastrophe.

It ignores that people can think and fix things. Re the current situation, world population is predicted to peak shortly and solar is cracking along.

> hardship, want and greater susceptibility to famine and disease

Have you been awake for any part of the last 50 years? Two of those things are happening right in front of you, with the third on the horizon.

Yeah but not really caused by a population explosion and mostly not getting worse. The UK for example went from 10m people when he wrote that to 66m now but has more food, money etc per capita.

It's not that hard to imagine scenarios over the next few decades in which we find ways to use resources far more efficiently (e.g., improved battery technology, improved factory-made meats/foods), find ways to extract far greater resources from space (e.g., improved solar technology, asteroid mining), and/or find ways to expand the resources available to us (e.g., establishing colonies on Mars, or in space).

Improving efficiency doesn't address the problem at all. If you only improve efficiency then consumption grows to negate any gains.

Improving efficiency means we can at least potentially retain current levels of consumption. Not that this is a particularly good idea but it shows why it is relevant.

Except the entire problem is that current levels of consumption are unsustainable.

They are unsustainable at current efficiency levels. If things got more efficient, they wouldn't necessarily be unsustainable.

No.... the amount of energy consumption is unsustainable at any efficiency level.

But, what I think you're saying is that if we can increase efficiency by X%, then we can still sustain current economic output, yes? Well, considering we're 70% over the sustainable level, that means we'd need to get 58% more efficient, with no increase in consumption, in less than 20 years.

How likely do you think that is?

Citation needed.

Our current energy needs could be harvested from the sun exclusively. Cover sahara in solar collection and you satisfying energy requirements of all of humanity, several times over.

Extracting resources from space, and expanding to Mars or space colonies are likely non-starters due to simple physics. No matter how you do it, it takes around 100 MJ/kg to get something into orbit, which translates into about 28kWh of electricity per kg, to offer a more relatable comparison [0]. It costs roughly the same amount to land the equivalent amount of mass on Earth without making an impact crater.

One single, average human weighs somewhere around 65kg. So, not counting the mass of the fuel and vehicle necessary to do so, evacuating one human costs the energy equivalent of around 1820kWh of electricity. The average American household uses just over 10000kWh per year [1], just for comparison.

Now, let's get to the bad news. Remember the weight of the vehicle and fuel that we just conveniently forgot about? Let's not forget about it anymore.

Falcon 9 weighs around 550,000 kg [2]. So, just to put it in orbit, empty, costs the equivalent of over 1.5x10^6 kWh of electricity, or, roughly the yearly consumption of 1500 years worth of the average American household's energy consumption. That energy has to come from somewhere.

Tell me, how is space going to save us again?

On the other end, in less than 20 years, we need to not only offset the trend of 50% increase in global energy consumption, but also cut back an additional 50% from where we are today. In other words, in 20 years, in order to simply break even in terms of sustainability, we need to become 3x more efficient than we ever have over any 20 year period, if we want to maintain current levels of economic growth.

And you don't find that hard to imagine?

Edit: Alternatively, do you see us supporting 2 billion more people on this planet in 2050 with lower levels of economic growth than we've had the past few decades?

See https://en.wikipedia.org/wiki/Projections_of_population_grow... for population growth estimates.

---

[0]: https://space.stackexchange.com/questions/4330/how-much-ener...

[1]: https://www.eia.gov/tools/faqs/faq.php?id=97&t=3

[2]: https://www.spacex.com/vehicles/falcon-9/

I don't think "space" is a short term solution in the slightest. It's more an eventual, partial solution.

Wouldn't the general idea be to put things like solar cells into space, to increase the amount of harvestable energy we can use, not humans?

Very long-term projects like space elevators, mass drivers etc. can help reduce the amount of energy (from Earth) that is required to efficiently launch something.