So what is sEROI anyway? Lets start with what is EROI... Energy Return on Investment is a ratio of how much energy you can get out of an activity versus how much energy you put into that activity. Historically energy feedstocks change as depletion - or the consumption of that resource - results in depletion which typically alters the EROI over time. How does that happen? Well for example, early oil wells produced 100 times the output for each energy unit consumed. In other words, for each gallon of fuel used to dig the well, you got back 100 gallons of oil. Nice - think of that as the good old days but I warn you it was a once and done deal.
Today the EROI ratio for oil has fallen to 15:1 a huge difference, and as oil depletes it will take more exploration, deeper wells and geographic challenges that will make energy in vs energy out converge towards 1:1. Think of this as our worlds gas tank being full in 1930 and down below the one quarter mark - sorta between that last quarter and EMPTY. If you were driving a car and noticed that, you'd be feverishly looking for a gas station. But alas, planet Earth has no cosmic filling station. Hmmmm, maybe we should be paying attention to this.
As a footnote to this topic, no modern civilization can expect to see economic growth with an EROI under 10:1. Stagnation, yes - growth no. De-growth as the ratio moves towards 1:1, with economic collapse occurring somewhere in between.
So that was EROI. sEROI is the broader reality of the system required to produce that energetic thing. Solar panels for example, require consumption of a lot of energy dedicated to mining stuff like Neodymium, Dysprosium, and Terbium, Lanthanum and Yttrium, Cerium Oxide, Indium, Gallium, and Tellurium, which all have to undergo concentration of these mined ores so they can then be made into panels, frames, and don't forget the huge furnaces that burn more fuel so we can make the panel glass, then more mining of low grade copper to make wires and various other components. Then in this example, when the solar panels are no longer efficient, we can recycle the few parts that can actually be recycled at economic EROI and dispose of the toxic waste. In fact it costs about $40 USD to recycle a panel and $5 USD to toss it in a landfill - so guess where they all end up. This is an example of a total life cycle system. For solar panels that are analyzed over a full life cycle which includes, creation, use and toxic waste disposal - an "extended" EROI typically falls near or below 3:1 and that's if you actually get a 20 year life. That's a sketchy number too, many believe 15 years is about right but pay attention to the warranty offered - you very much get what you pay for and degradation is a fact in batteries and photovoltaics*. Statistical life numbers depend on chemistry and long life panels are very expensive. Buyer beware - not all solar panels are the same! If you go further into the system and consider the extended EROI for batteries, grid buffering and back up generation plants that must come on when the sun isn't bright enough, you barely break even, truthfully, we are probably net negative. Certainly well below 3:1 which suggests that this is not a sustaining source, but probably a net energy sink that isn't obvious until you look at the system EROI. By the way both solar panels and wind systems drive an exotic mineral demand/dependency that is 10 times greater than a typical fossil fuel energy source. With a concomitant knock on effect of fueling up the mining, refining and waste remediation just to get the raw materials created and available for manufacture. Both have long supply chain tentacles that are energy hungry and come along with dubious environmental impacts.
The often mis-used phrase of "renewable" is more aptly described as "re-buildable at a cost."
So for example, solar PV extended EROIs look like 2:1 or maybe 3:1 in really favorable locations not the generated number from the finished good. Wind power may be as high as 7:1 but more typically 4:1 or 5:1. By the way, ethanol the magical bio-fuel has an EROI of 0.7:1 lol the definition of an energy sink. Fracked oil - around 5:1. All forward looking energy feedstocks say "holy cow."
So the take-away is: Oil is the whole economy. Green isn't very, and renewables are not. The real question I have for you and the world in general is, why are we not in a serious conservation mode? That is the only strategy that makes much sense to me. Simplify, get regional, reduce your energy needs.
As energy EROI continues its glide towards 1:1 also realize that long before you get there, the energy used to reinvest in making more energy will consume societal needs like infra-structure, road building, steel making, fixing bridges, paving roads and fertilizing farm fields. Energy cannibalism will happen, as competition for the available BTUs increases. Your local data center will eventually be competing for your irrigation water and available power for your home - I'm not kidding. GDP will also decline with disproportionate impacts depending on where you live (helpful to live by a hydro plant) and which government you are a part of (I like Sweden and Norway). This grab for energy dominance appears to be the motivation for many of the bazaar events happening on a global scale right now. But all of that aside, the end game is the same. You can - through conquest - control all of the black gold aka Texas Tea for a while but it is a finite resource and as it is consumed we all share the same fate. Keeping all of your marbles also burns resources, remember once and done. History is a great teacher if you bother to read about it and can comprehend it. Buy a fishing pole and learn how to fish. Plant a garden, get a scooter. Don't forget to laugh often and cherish your loved ones. The world did just fine before 1800. Get to know your neighbors and have that block party. Now as an objective student of history what do you notice about populations? It was about 1 billion souls. Napoleonic Wars were just kicking off because - Europe was looking for resources. As the industrial age supported further growth, there came the Crimean War, the Taiping Rebellion, the Mexican-American War, the Paraguayan War the US Civil War and the Spanish-American War. Every one a resource driven slaughter. Growth is hard, de-growth is too. Take away, albeit gradually but steadily, energy and there will necessarily be battles for resources. Our failure as a population to work things out, share and share alike etc., has never been our strong suit. My own thought about this is that the 5% of our population that has no empathy or remorse and doesn't truly experience love - the sociopaths and psychopaths sprinkled in among us tend to rise to authoritative roles and as they manipulate harm and get what they want they acquire a sycophantic legion of followers who beg for the spoils. Then it all goes side ways as trust and compassion for fellow man is destroyed. My 2 cents.
* Just a little clarification about degradation. It may not sound too bad to read or see numbers like the typical 1% per year loss, but that small percentage has some dire consequences to the system components of the solar power installation. Inverters have a lower life span - maybe 10 to 15 years if all goes well (your array by that time has lost around 15% of its output - if it was made from quality components), but inverters tend to thermally overheat and see fatiguing thermal cycles while trying to deliver demanded power as panel efficiency drops off. Oopsie, nobody told you about that - what happens then? Some inverters just shut down as panel efficiency drops simply to avoid self destruction - then here's what happens next, you get to replace your panel(s) selectively in a high tech game of whack a mole that eventually cascades through the entire array. So expected ROI based on life should really be based on over-sizing which will eventually hit degradation limits associated with demanded power and battery storage as both panels and batteries show efficiency loss over time and charging cycles. Don't forget to add hail damage to your solar array covered in your home owner's insurance policy either - usually a 15% to 20% increase in your premium. Now you know a little more. Keep learning my friends.
Today's alternate energy devices can be thought of a bridge to someplace that looks a lot like the early 1800's. How long 'til we get there? That depends on how civilized we are and if we can work together - globally. I suspect we won't deviate from our historical track record, so looking back is to look forward - just change some names. You can posture yourself well though by just adapting to a more natural life. Really, plant that garden, or join a co-op. Nothing wrong with building your own energy independence, just realize it's finite and expensive. But maybe that's ok for you. Maybe you live in a neighborhood where resources could be pooled. Get that scooter, they're fun and can get 134 mpg. That's amazing. If it fits into your lifestyle consider how significant that would be.
