Chances are that if you're reading this you probably live in an economically advantaged country. There's lots of paved roads, the food choices are abundant, the arts proliferate, leisure opportunities abound around nearly every corner, health care is available to all (unless you're in the US), retirement is the norm (although once again becoming not so), and there's a sizeable enough military to back it all up with.
Conventionally, we're led to believe that the existence of all these necessities and luxuries is the product of generals, politicians, an educated class, superior economic systems, advanced political systems, and so on. However, nothing could be further from the truth.
Because the fact of the matter is that our modern civilization, and all of human history in fact, is the result of exploiting energy supplies and the technologies that allow us to harness those energies. Whether it be a gatherer-hunter gambolling about to procure food, or an urban sophisticate dining at a destination wedding in some exotic corner of the world, what makes our lives possible is the pre-condition of available energy. And more specifically, the pre-condition of a surplus of energy.
Energy surpluses are required for the simple fact that without them we'd all start to expire: if a band of gatherer-hunters spent more energy collecting and chasing after energy (in the form of food) than what they got back in return, they'd soon start to starve. But while the gatherer-hunter's supply of energy has a relatively direct route of sunlight → plant (via photosynthesis) → (possibly) animal → human, the predominant source of the modern-day human's supply of energy instead takes the indirect and rather circuitous route of coming in the form of highly concentrated and ancient sunlight – fossil fuels.
Without exception it is the abundance of fossil fuels that makes modern civilization possible, and what makes fossil fuels so different from the gatherer-hunter's energy source(s) is their energy return. First of all, it takes energy to get energy – the gatherer-hunter must expend energy (walking and running around) to collect energy (food), and as mentioned, must come up with a surplus of energy. But while plants and seeds and the occasional woolly mammoth could pull in a fair-sized energy surplus, fossil fuels can provide such an enormous energy surplus that they allow for the descendants of gatherer-hunters to drive to restaurants in enormously heavy steel boxes, have their meals prepared for them by other descendants of gatherer-hunters, and be doted upon by yet even more descendants of gatherer-hunters whose access to energy surpluses are almost guaranteed to be less than those doted upon, but still enormously high compared to their ancient ancestors who lacked the table manners for the proper use of cutlery. (And flush toilets! One can't possibly dismiss those wonderful flush toilets!)
To differentiate and measure the energy surpluses that various sources of energy supply is where the metric devised by systems ecologist Charles A.S. Hall comes in, Energy Return Over Energy Invested, commonly known as EROEI. Focusing singularly on energy, EROEI assessments are a measurement immune to financial vagaries of tax credits, resource subsidies, and other market fluctuations that distort data. EROEI levels are stated as a ratio, where a 5:1 ratio means you get back five units of energy for every one that you put in. That these ratios can differ widely between energy sources – and have been significantly dropping in recent years – has significant importance to our high-levelled energy dependent modern civilization.
Moreover, there is also the issue of which factors should be taken into account when calculating EROEI levels. Should the electricity used in the manufacture of photovoltaics be counted? Of course. But what about the diesel necessary to mine the necessary rare earth metals? What about the energy required to heat the factory for the comfort of the factory workers? What about the energetic costs of benefits like health care plans (which differ from country to country, therefore affecting EROEI calculations from country to country)? What about labour costs? What about the energy needed for decommissioning? Suffice to say this can get rather contentious, and seeing how some energy sources have rather low EROEI levels (as will be described shortly) and that higher numbers obviously look better, it should come as no surprise that certain vested interests have been known to adjust the variables in order to get the answers they desire.
That all being said, in the late 19th century when oil fields began to be tapped, crude oil supplies were under such pressure that EROEI levels were often in the high 100:1 range. But since the most accessible and highest returning fields were tapped into first (rationally, of course!), oil fields have been yielding progressively shrinking EROEI levels since what's left is becoming harder and harder to reach, requiring ever more and newer energy-intensive technologies for extraction. What used to be an average (in the United States) of about 100:1 saw a drop down to about 36:1 by the 1970s, and then down to about 18:1 by 2008. (Saudi Arabian crude oil remains much higher for the time being, in the 40:1 range.) Furthermore, coal and natural gas have also been seeing their EROEIs dropping over the past several decades.
What does all this mean, if anything?
Simply put, with less energy surpluses we're not able to do as much stuff. A good descriptor of this is Charles Hall's "Hierarchy of Energetic Needs," which points out that the lower EROEI levels get, the less activities a civilization is able to partake in. Energy is required not only to grow and harvest food, but to process that food, maintain the retail outlets to sell that food, power delivery and commuter vehicles, maintain public transport systems, provide education, healthcare, and welfare, build and maintain all the infrastructure, and quite possibly defend it all with a strong enough military and government.
For example, to maintain an art industry requires an EROEI of 14:1, a health care system requires 12:1, an education system requires 10:1, and so forth, all the way down to the point where you're devoting what few energy supplies you have to simply moving energy around, leaving nothing to actually produce any good and/or services. Go below a 3:1 level and it's not really worth pulling it up out of the ground, implying that there's going to be a large quantity of leftover crude supplies that will simply go unextracted. In short, the lower that EROEI levels get, the less that modern-day societies will be able to maintain their taken-for-granted institutions brought about by fossil fuels and industrial civilization. It should go without saying then that since none of this gels with the continuance of business-as-usual (and agriculture-as-ususal and art-as-usual, etc.), EROEI gets virtually no play in public policy and has very minimal public awareness.
Regardless, since all the easiest to reach (and thus higher energy bearing) fossil fuels have already been extracted, this is increasingly leaving us with less and less of the "good stuff" and more and more of the dirtier and more (energetically) costly to extract and refine stuff – such as Canadian tar sands oil (which at an EROEI of about 4:1 can't even maintain a modern education system, never mind the lauded Canadian health care system). So-called "renewable" energies aren't all that much better either. Wind energy can have an EROEI of around 15:1, but that doesn't take into account the cost of a backup energy system for when the wind isn't blowing. Meanwhile, solar photovoltaics have an abysmal EROEI of about 2.45:1 (according to Charles Hall's book Spain's Photovoltaic Revolution: The Energy Return on Investment). And even worse, many biofuels continue to be dogged with the argument of whether they are a net energy loss or gain, the range of many of their EROEI assessments being between 0.8:1 and 1.3:1. But as we have seen, an EROEI of 1.3:1 is so negligible that it's a virtually pointless endeavour, and the only thing keeping most biofuel ventures going is government subsidies which give them the sheen of respectability. In short, biofuels are a project that should never have been undertaken in the first place, but the pockets they've lined of investors getting in (and presumably out) of the sham before the bubble pops, along with those of their political lackeys, have seen differently.
Furthermore, there's the whole problem with so-called "renewable" energy sources not being all that renewable in the first place. First of all, to mine all the rare earth metals necessary for the innards of windmills and photovoltaic panels requires massive machinery – all of which is powered by diesel – to extract said materials from the earth. Secondly, to construct photovoltaic panels and the massive windmills requires a fossil fuel-based infrastructure. And last of all, since batteries only have a life-span of about 10 years, and with photovoltaic panels and windmills lasting about two or three times as long, when replacement time comes along, the energy supplied by "renewables" isn't enough to create a new generation of "renewables," never mind the even greater optimistic expectance of powering industrial civilization in the first place.
This is partly because what "renewable" energies produce is electricity, which only makes up about 18% of worldwide energy usage, the rest coming from fossil fuels. With virtually all of our airplanes, trucks, and automobiles being powered by liquid fossil fuels, the problem we have isn't so much one of electricity, but of liquid fuels. To think that "renewables" could power our liquid-fueled transportation system is already enough of a stretch of the imagination, but to think that we have the energy – the high EROEI energy – to replace our entire liquid fuel-based infrastructure is a gargantuan folly.
To aid our understanding of all this is the depiction devised by Euan Mearns, the Net Energy Cliff, an assessment of the amount of energy needed to extract energy. With high EROEI ratios, the amount of energy required for extraction is rather low, and changes very little: an EROEI of 50:1 has a net energy availability of 98%; 33:1 a 97% energy availability; 20:1 a 95% energy availability. Past 10:1 the net energy availability starts to plummet though – 10:1 has a 90% energy availability, 5:1 an 80% energy availability, and 2:1 a 50% energy availability. And again, at 1:1 you're simply using a unit of energy to get back exactly what you put in.
As it so happens, the world now has an overall EROEI of about 14:1, and is drifting precariously close to that sharp bend of the Net Energy Cliff. Not only then will the death knell of industrial civilization become more and more pronounced as it goes over the Net Energy Cliff, but as EROEI levels slip past 10:1 and then further, more and more people will be required to busy themselves with energy procurement activities rather than those now offered by industrial civilization. This will therefore ultimately entail a significant amount of people working in harvesting energy from humanity's oldest and most indispensible source of energy – food. As industrial civilization comes to a close, and be they more on the altruistic side or more on the slavery-based side, the people, communites and societies that make it through the bottleneck of a drastically reduced population will be those that have somehow learned how to function with significantly reduced EROEI levels.
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