Comment by suoduandao2 | Hacker News Reader

Comment by suoduandao2 | Hacker News Reader

Parent Full thread

Regarding the question 'what specific thing is it hard to do without fossil fuels', the answer, from what I've seen of that side of the debate, is that the problem isn't technical but economic.

To attempt to steelman the argument AIUI: If we replace the EROI of fossil fuels with the EROI of renewables, a much larger portion of the economy will have to be dedicated to generating energy. This will make everything more expensive, and a lot of activity we take for granted today will be too expensive to be maintained, even though it might still be technically feasible. Even the leisure time to invent new and better energy sources will be displaced by people needing more time to chop their own firewood etc[1], and free capital to invest in new inventions will similarly be much harder to come by than when we were all comparatively rich due to the fossil subsidy. There will be knock-on effects in the complexity of society, which is currently able to maintain a high level of complexity and specialization because the high costs of complexity (e.g. longer supply chains) is being subsidized by the low cost of energy.

It's not a terrible argument, though it clearly is making a doomer assumption at every turn. Currently, google tells me that the EROI of crude oil and solar PV are ~20 and ~10 respectively - which does represent a significant tightening of the total wealth available if we contemplated switching everything today. The more optimistic counterpoint, is that the current EROI of fossils is diminishing, and will meet the EROI of renewables at some point, where by this logic the maintainable complexity of society would stabilize. Hopefully that still allows us to have a microchip foundry somewhere, though I haven't seen anyone reliably crunch the numbers one way or another.

[1]pointing out that Nikola Tesla invented a lot of things while employed digging ditches is not part of a proper steelman.

Naively, if our EROI halves, then we should be at worst half as rich, right? If that's the case then (again, very naively) you might expect that we would "merely" have to accept an average standard of living from when the world was half as rich, which would be about 2003-2004.Now, the world was much more very unevenly developed in 2003, so that doesn't mean rich countries won't have to come down while poor ones come up, but it doesn't sound apocalyptic to return to the Bush years in terms of wealth.

That said, I think the naive interpretation is wrong. IMO most of the wealth we've been creating since the 19th century is mainly about the task of applying cheap energy to new problems: perfecting power looms, artificial fertilizer, transportation, etc. If the energy becomes twice as expensive, it's not clear that we would only be half as rich. We might in fact be much much poorer than our ancestors were before the cheap energy, because the biosphere (our previous primary source of low-entropy raw material) is in far worse shape than it was in 1800 and needs to support many more people.

One hope is that green energy can actually exceed the EROI of fossil energy. If we can get high-efficiency, long-life (don't have to replace it for 100 years or more) PV, then it should be pretty easy to exceed fossil fuels' EROI. You have to dig more coal for every unit of coal-fired work, whereas you can manufacture a solar panel once and let it do unlimited units of work as long as it exists and the sun is shining.

Renewables have been higher ERoEI for a while.

It doesn't get mentioned much because only conspiracy theorists use ERoEI as a metric, because it's nearly totally meaningless, and so you need to find an actual scientist with the time and interest to show conspiracy theorists why their own sums are wrong.

2014 link:

https://bountifulenergy.blogspot.com/2014/07/renewables-have...

2018 update:

https://bountifulenergy.blogspot.com/2018/10/reports-of-low-...

General dunking on the whole concept of ERoEI:

https://bountifulenergy.blogspot.com/2016/06/eroei-is-unimpo...

Yeah, obviously the thing we want to maximize is the energy output per labor input, since the whole point of having this energy is to use as an input to further labor-saving processes. Chopping wood with an axe is bad on this scale. Coal and oil are much better. Renewables have the potential to be even better, if they aren't already.

Thanks for these, they are a good way to voice something that I've always felt was a problem with the EROI crowd's thinking.

> Naively, if our EROI halves, then we should be at worst half as rich,

Interesting question. Not if energy is used to build things that then build things, which it is. Depending on how long that "chain" is on average, the efficiency difference can compound exponentially.

For example, if you have 3 chains of repeated processing, and each link is made 10% more efficient, the total output is increased by 1.1^3, or about 33.1%

I am not sure what kind of a number you could empirically estimate for the "average chain length" of the physical "tool chain" used to produce modern industrial goods, but it's probably at least 2, which would suggest halving efficiency yields cutting final output four-fold!

And yes, I don't actually have a real idea of the answer because it also depends on many other factors like the degree to which energy is the limiting resource for each individual step, how fast capital amortizes (literally how long a factory part lasts between replacement, essentially), etc. I really have no idea either. But my first back of the envelope initial guess would be more pessimistic than "cut efficiency in half, get half the output"

Source: ....got addicted to factorio last week. Please send help.

I believe this particular author admits that the ERoEI of renewables is in fact higher than fossil fuels and unlike them increasing.

Could be wrong on that. He definately mentioned ERoEI which set me twitching as usually that indicates insanity is about to follow. But in this case I think he got ERoEI correct but then just somehow got to the same bad conclusion that people who get it wrong do.

edit: on reflection he wasn't quite as explicitly positive as I recalled:

> That in itself is not particularly problematic. Based on the favorable energy return on energy invested (EROEI) in renewable technologies—well above break-even

But still seems enough to make that complaint irrelevant (depends on whether he buys into the society needs X and renewables and nuclear can only provide Y stuff. Which some of his other comments seem to imply).

Note that ERoEI is a nearly totally useless measure and the vast majority of people quoting it do not even understand what they are saying. So all of this bit of your steelman isn't even wrong, just doesn't really make any sense.

> To attempt to steelman the argument AIUI: If we replace the EROI of fossil fuels with the EROI of renewables, a much larger portion of the economy will have to be dedicated to generating energy. This will make everything more expensive, and a lot of activity we take for granted today will be too expensive to be maintained, even though it might still be technically feasible

Reply on news.ycombinator.com