Help me understand the significance of EROI?
According to this guy, societal collapse is imminent because a. entropy and b. the high EROI (energy return on investment) afforded to society by the use of energy dense hydrocarbons such as coal and petroleum will decline dramatically in the near future due to the decreasing economic viability of acquiring them and the lack of a similarly high return alternative (barring nuclear fission, which is VeRy DaNgErOuS (and also practically infeasible politically in most countries that can achieve it), and nuclear fusion, which is, of course, perpetually 20 years away) and because this EROI is (according to him) what makes the complexity of modern civilization possible, it is inevitable that we will soon see a corresponding decline in said complexity (collapse). Now there is a section in the wikipedia article that touches on some of these points (Economic influence) so it's not totally junk science (if you trust Wikipedia, that is). However, I'm still struggling to grasp the significance of this figure. As long as our means of acquiring energy is scalable, why does it matter what the EROI is as long as it is greater than 1? if we need to spend one fifth of the energy we get from solar panels on making more, fixing existing ones, and installation, can't we just make a bunch of them to match our energy needs, even if they're growing? What am I missing here?
You have every reason to be skeptical of any given peak oil claim, because every year that churns by falsifies half a dozen well measured peak oil studies. We have seen hundreds of studies and dozens of models collapsed in the face of new finds, over and over. It would be naive to assume that we won't see peak oil in our lifetimes, but it would be similarly naive to just hop on the next hot model that predicts peak oil is three to five years away.
https://en.wikipedia.org/wiki/Predicting_the_timing_of_peak_oil
I don't think we are going to see a precipitous decline in plastics and petrochemicals any time soon though, and plastics production doesn't release CFCs in the same way that gasoline usage does. I largely agree with you otherwise, but I think eventually oil derived hard goods will drive us to peak oil. In that regard it's not much different from lithium however.
As I understand it, making a bunch more solar panels is (according to this theory) exactly what precipitates the collapse. You end up with proportionately more of your economy devoted to building and maintaining the energy infrastructure, and less devoted to everything else. As the energy needs grow, the equation swings ever further towards that until all other productivity grinds to a halt.
If the change in EROI is rapid, the shock becomes all the worse because it's not just that an extra (say) 3% of the economy that needs to be devoted to the energy sector each year, giving people time to adjust, but that an extra 20% needs to be retooled overnight - and in turn everything that labour and capital was previously supporting must stop.
As for the theory itself, I think that predictions of total collapse are overstated. People will get over their fear of nuclear fission, industries will work out ways to more efficiently do the things they were doing wastefully, yields will improve on renewables, and things will largely continue moving forward.
We've been giving ourselves a century-long free lunch on oil in a lot of ways: ease of access, climate impact, abundance. There's going to be a serious sting as that comes to an end, and many people are going to be worse off for it. Things may well really fucking suck in a lot of ways, perhaps for decades. But we'll adapt.
Complex, modern society can still exists in an energy efficient way, there just hasn't been sufficient pressure to force it to do so yet. On the one hand, paying back the energy debt that got us to this stage will hurt; on the other hand, the tools and infrastructure that humanity bought with that debt - computers, robotics, satellites, the internet - put us in a far stronger position to succeed than we were before this whole experiment began.
I took a course called 'Creative Computation' and one of the homework exercises was to try to compute how many years of different non-renewable resources we had left on earth at current usage rates (this was back ~10 years ago). While oil can’t really be estimated precisely because of different technologies used to locate and extract it, the consensus from the class was that we had at least 300 years of oil at current usage rates and extraction technologies/costs. Presumably that number will only go up as fuel efficiency increases and demand decreases.
It struck me to go find some of my relevant homework (circa 2010) from that course, so I’m going to reply to my own comment here, because it’s rather interesting (the whole course was rather interesting as it was a pilot of a course designed to be part of a general engineering undergraduate curriculum, and it’s rather satisfying to sit down and look up figures and compute your way to interesting results):
Energy Production from Switchgrass
A 10 year study of biomass yields of swtichgrass in test fields in Oklahoma found the average to be roughly 13.5 Mg (megagram) / hectare or ~1.35 Mg / ㎢ (square kilometers) / year. Other sources note that switchgrass is capable of producing up to 15 Mg / hectare / year or ~1.5 Mg / ㎢ / year. During the process of converting the raw biomass to fuel, the lignin fraction of switchgrass can be burned to provide sufficient steam and electricity to operate a biorefinery so this step shouldn’t require additional energy input. At current rates of conversion (circa 2010), dry switchgrass biomass can yield up to 120 gallons of ethanol / dry ton or ~35 L (liters) / Mg. So for the sake of computation, at the higher rate of 1.5 Mg / ㎢ / year, that is ~50 L / ㎢ / year. The total rain-fed arable land in the world is ~4×10⁷ ㎢. Ethanol energy density is ~21 MJ (megajoules) / L. So if all arable land were devoted to ethanol production that would be 50 L / ㎢ / year × 4×10⁷ ㎢ × 21 MJ / L which comes to ~4.2×10¹⁰ MJ / year.
By contrast, 42 gallons / barrel of oil can be refined to ~19.5 gallons of gasoline which is ~74 liters. The energy density of low octane gasoline is roughly 30 MJ / L so that would be 2.22×10³ MJ / barrel of oil. In 2006, 8.524×10⁷ barrels of oil / day were produced so that would be ~1.892×10¹¹ MJ / day or ~6.907×10¹³ MJ / year total energy from oil. This is ~1.645×10³ times as much energy on a yearly basis than could be produced from switchgrass even if all arable land were devoted to bioenergy conversion. I haven’t taken into account the energy cost of refining the crude into gasoline, though, so one would have to subtract that from the total energy from oil production. The energy from switchgrass couldn’t even reach this theoretical value, however, as much of available arable land is required for food crops to sustain people and livestock.
It’s likely that with further genetic modification and improvements in ethanol bioconversion techniques that the energy per area of switchgrass could improve, but it seems unlikely to me that a ten fold increase in efficiency could be squeezed out. At this point, though, it would seem quite unrealistic to expect to maintain current energy consumption through bioconversion of switchgrass into ethanol fuel. The largest gain in efficiency of bioconversion might be obtained through engineering bacteria which would break down the entire switchgrass plant, including the lignin, into biofuel, unlike current refinement processes which only convert a fraction of the total biomass to fuel as the lignin/woody parts are not converted.
Solar Energy Production
Wikipedia cites that photovoltaic arrays (PV) can achieve ~1 kWh (kilowatt hour) / ㎡ (square meter) / day under average conditions. Wikipedia further suggests that a 150 watt solar panel ~1 ㎡ in size can be expected to produce this 1 kWh /㎡ / day based on average latitude and weather conditions. Under optimal conditions, such as in a desert with no cloud cover facilitating uninterrupted sunlight, a panel may reach up to ~8.3 kWh / ㎡ / day. Across Europe and the U.S. the value is closer to ~5 kWh /㎡ / day.
In 2008, total worldwide energy consumption was some ~4.74×10² EJ (exajoules) (~4.74×10¹⁹ J (joules)) or ~1.5×10¹ TW (terrwatts) (~1.5×10¹³ W (watts)). Taking the value of energy output of an available PV at ~5 kWh/㎡/day for the U.S. and Europe and the conversion from kWh / day to W is ~42 W then a PV can generate ~2.1×10² W / ㎡ or ~7.7×10⁴ W / ㎡ / year. In the desert where optimal conditions may allow up to ~8.3 kWh / ㎡ / day then a PV could generate ~3.5×10² W / ㎡ / day or ~1.3×10⁵ W / ㎡ / year. To fulfill the world’s energy needs this would require some ~1.9×10⁵ ㎢ of PV in the U.S. or Europe or equivalent and some ~7.9×10⁴ ㎢ of PV in, say, the Sahara Desert. This would mean covering some ~2% of the land area of the U.S. or less than ~1% of the area of the Sahara with PVs.
The issue with PVs, however, lie not with their total energy production capabilities or scalability. For instance, the Sarnia PV power plant in Ontario, consisting of over 10⁶ panels, is, as of September 2010, the world’s largest PV plant and is producing 8.0×10⁷ W of energy. The trouble with PVs lies in maintenance costs and the fact that the energy (like wind power) can be inconsistent and peaks during daylight hours. As the technology develops further, greater efficiencies will increase the wattage per area for PV, but the infrastructure for storing and transporting energy garnered from PV would need to be significantly ramped up for PV to feasibly supply for the world’s continuously growing energy demands. Technologies that may assist in this effort include large batteries, such as molten salt batteries.
I can't address everything, but it doesn't seem realistic to me that society would collapse due to changes in EROI. One reason for this is that our society is very inefficient with our energy, this provides us flexibility. You can relate this to the supply chains we saw failing during the pandemic. Efficiency is optimization for how things currently are. However, we aren't very efficient and so if EROI drops we can be forced to be more efficient with our energy usage to make up for that change.
That isn't to say that a dramatic change in EROI wouldn't cause panic and change, but it by itself wouldn't lead to collapse IMO.
I'm no expert and I didn't watch the video, but as you describe it, it doesn't make much sense to me either.