Ok, I tried... I couldn't stay out of this thread for very long.
Quote:
Originally Posted by Tinordi
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This might be exciting if you're arguing against people that make claims that panels don't produce as much energy as it takes to produce them. An EROI of 7-15x is nothing to celebrate. I will explain.
Quote:
Originally Posted by Bownesian
Unfortunately, much of that article is behind a paywall, but I'll retract my statement.
In the bit I could read for free, the authors made a good point in that as oil becomes more scarce, the EROI has dropped from more than 100 in the 30's to more like 10 now (which is about where the authors place solar in an ideal location).
Notable is that that EROI drops significantly when solar energy is buffered (i.e. stored in batteries for sustained use), and notabe as well, is that higher EROI is for PV-cells in low latitudes in a desert, where if they are in a place like Canada, the return becomes much less (similar to the Germany numbers below).
Also, the EROI returns are much lower than other sources and are thus only minimally profitable. The paper and figure below have similar numbers to the one you quoted (which had a high EROI of 12 for PV-sources) and illustrate the problem.
http://energytransition.de/2014/09/r...es-ko-by-eroi/
CCGT = Combined Cycle Gas Turbine (nat. gas) |
That weisbach study that you quote has been
debated and there are certainly arguements that suggest some versions of solar PV in ideal conditions may have an EROI as high as 20-25. But
other studies have been performed that suggest the Weisbach work is not far from the truth.
And THAT is the key: EROI.
Healthy EROI is essential in sustaining an economy. Every economy requires a different EROI on it's energy mix to remain viable, depending on how advanced it is. Without sufficient excessive EROI, a society cannot sustain it's activities, and it will recess to the point where it is at risk of collapse.
Societies face a great many number of pressures, and abundant energy supply is one of the aces up our sleeves to ensure continued vitality and expansion.
The work performed by researchers Homer-Dixon and
Hall established the term EROI in academia, it is a relatively new concept. These gentlemen suggest that the minimum threshold EROI to prevent the entire collapse of a society is around 3, by analyzing past societies that did indeed collapse. Anything less than 8, and an economy is sitting precipitously close to the edge of a cliff where a society will rapidly tumble down a cliff towards investing far too much energy to get it's energy to make it sustainable. The relationship is asymptotic.
From Hall, quoted in an interview in Scientific American (2013):
"What happens when the EROI gets too low? What’s achievable at different EROIs?
If you've got an EROI of 1.1:1, you can pump the oil out of the ground and look at it. If you've got 1.2:1, you can refine it and look at it. At 1.3:1, you can move it to where you want it and look at it. We looked at the minimum EROI you need to drive a truck, and you need at least 3:1 at the wellhead. Now, if you want to put anything in the truck, like grain, you need to have an EROI of 5:1. And that includes the depreciation for the truck.
But if you want to include the depreciation for the truck driver and the oil worker and the farmer, then you've got to support the families. And then you need an EROI of 7:1. And if you want education, you need 8:1 or 9:1. And if you want health care, you need 10:1 or 11:1.
Civilization requires a substantial energy return on investment. You can't do it on some kind of crummy fuel like corn-based ethanol [with an EROI of around 1:1].
A big problem we have facing the alternatives is they're all so low EROI. We'd all like to go toward renewable fuels, but it's not going to be easy at all. And it may be impossible. We may not be able to sustain our civilization on these alternative fuels. I hope we can, but we've got to deal with it realistically."
Here is an
interesting interview with Hall himself, if you'd like to hear more. His book Energy and the Wealth of Nations is very, VERY good.
A troubling trend, when plotting EROI of various energy sources throughout recent history can be witnessed here:
EROI is declining rapidly, even for oil. This is what people mean when they say "the easy oil is gone". It takes more money, but more importantly, more energy to harvest and use what is still available. We cannot keep doing this and expect it to be good for our now global society.
You can see that solar is already on the sh*t end of the spectrum and this is after a century of research and effort to get it to the point that it is marginally viable. We can't move from an energy supply that was 100 or greater on an EROI scale, and replace it with something that is 10 on average (worse when we use batteries), and expect that the way we live will not be SIGNIFICANTLY impacted.
Any country that builds it's base on energy with low EROI like biomass, solar, wind... it will be in energy poverty. If anything like drought, or famine, or disease or war ever came to stress this nation, it would be like putting a malnourished hobo in the ring against Mike Tyson in his prime. Lights out.
I repeat, we need to be moving on from hydrocarbons if we expect ourselves to sustain (or dare I say grow) our populations and conserve (or dare I say stimulate) our environment. But it is clear when you analyze this data that solar is worse than hype, it is signing on to a global death sentence. It is unacceptable, and we need to be looking for the next best solution that can set us up to provide an abundant existence for every life form on the planet.
