...you can't destroy energy, but it does flow in a one way direction...

Hence the stupidity of the term "renewable energy." Elements recycle energy doesn't. Yet you can't get these facts thru to what passes for the brains of these "renewable energy" advocates. Same for the fact that EROEI analysis needs to include ALL inputs, in order to be meaningful. Since all inputs aren't known or can't be quantified, EROEI analysis can't be meaningful. This fact doesn't prevent 'em from making multitudes of colorful grafts w/ the chart wizard. There they sit at their computers as the house (oikos) burns down.

Perhaps renewable fuels is more accurate but is the wind considered a fuel and the thermal mass of a passive solar house also a fuel? Is the water behind a hydropower dam a fuel? Wood is a renewable fuel only if the land is properly managed. Ethanol could be a renewable fuel if the fossil fuel inputs were eliminated. Getting hung up on semantics with writers who are scientific illiterates doesn't help the cause of eliminating fossil carbon fuels.

Getting hung up on semantics with writers who are scientific illiterates doesn't help the cause of eliminating fossil carbon fuels.

Yeah, I agree, but we aren't exactly talking about quantum physics or the theory of relativity here. I would think one could reasonably expect a little more precision in the use of the Anglo Saxon vernacular by such writers.

It's really quite simple, the water behind a dam, for example, has static potential energy that can be released to produce usable kinetic energy, when the gates are opened and the water flows through a turbine and generates electricity. While fuel containing hydrocarbons can be combusted in the presence of oxygen in a chemical reaction that releases potential energy in the form of heat which in turn can be used to do work. Just basic concepts from high school physics and chemistry,based on the laws of conservation of mass and energy. This isn't exactly E=MC2,since we are leaving nuclear energy out of this for now ;-)

Just basic concepts from high school physics and chemistry,based on the laws of conservation of mass and energy. This isn't exactly E=MC2

Like the rest of us nerds here at TOD, you were probably sitting in the front row of Mr. Kotter's science class, raising your hand, and saying, "Ooh ooh, Mista Kotta, I know the answer to that question. It's simple, energy and mass can neither be created nor ..."

But if you had bothered to turn around and look at the back row, you'd of seen Vinny and the boys dozing off on their desktops (these were not computers back in the old Mr. Kotter days) ... probably they was dozing off on Ludes and stuff.

Anyway, many years later, Vinny and the boys woke up and realized they need to become "professionals" and get a job. "Go to business school," their moms said. And so they did.

There they learned fundamental principles of "economics", like supply, demand and how the bountiful commodities of our society are "produced" (yeah, yeah, "created", whatever) by them who do the "producing" in our society.

But financial types don't have to worry about that techno-nerd stuff. Financial types do the financing. That's their job.

"You want a default derivative swap buddy? I got one right here for you pal."

"Physics? Chemistry? The laws of conservation of mass and energy? E=MC2? Sorry buddy, I don't remember any of that elementary stuff. That's only for Fifth graders. Right?"

I would go along with you in a profound scepticism of most EROEI calculations, but on occasion where it is kept fairly simple then it can have some approximate use, for instance in showing the absurdity of ethanol from corn.

Mostly of course it is used as a polemic to diss whatever energy source the writer dislikes, rather than with any more profound analytic intent.

The term "renewable" is perhaps unfortunate. Perhaps a better term, though somewhat unwieldy, would be "local, current, solar energy, be that photovoltaic or wind or bio or whatever".

the rest [of the energy is] transferred to the rotational momentum of the earth (as I understand it at least)

Well, not exactly. It gets radiated out into outer space as IR radiation emitted by the atmosphere. Energy is constantly outflowing from the Sun to the outer reaches of the solar system. The Earth is like a little pebble caught in the flow of this mighty river. Some of the energy flow gets temporarily trapped here (i.e. as oil plus un-bounded oxygen). But ultimately it is released (when C combines with O2) and the released energy then continues its entropic journey to the outer reaches of the solar system.

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It could be called "sustainable" energy instead of "renewable"

Definition of renew:

To make new, or as new, again; to restore to the same condition as when new, young, or fresh.

Oxford English Dictionary

Hence the term renewable energy because a renewable energy source is constantly renewed/replenished from another (usually the sun). Renewable is completely different to reusable. There is nothing incorrect about the termrenewable energy as this refers to the replenishment of the energy source, not to the constant recycling or reusing of the same energy. Reusable energy would certainly be a stupid term, which is probably why no one uses it.

The sun is ultimately a finite source of energy, but this is not really relevant on a human timescale. The output of the sun is not under human control and the sun is not 'depleted' by human activity as other energy sources (such as fossil fuels) are.

As for EROEI, that fact that it can't be measured exactly does not make it meaningless. The declining EROEI of oil for exmaple, can be shown by reference to increasing rig counts and footage drilled. As a smaller subsystem within a larger one (your 'oikos'), the human economy is subject to the same laws governing energy capture and use as any other smaller system (e.g. ecosystems and individual organisms). Of course EROEI calculations can be biased and manipulated just like any other statistics but this does not make the concept of EROEI meaningless.