Bazz (continued)

"Imagine, if you are game, the massive battery or similar device, that
would be needed to store enough electricity for say NSW & Victoria
for perhaps five days plus enough left over to restart the system
after the slow moving front moved out into the Tasman."
The solar output wouldn't drop to zero, and the wind output would be higher than usual in that time, so you wouldn't need enough storage to supply the entire amount of power needed. But if we move to 100% renewable energy, it would make sense to have heavy industry (including fuel synthesis) that would operate when there's excess power and shut down when there's a shortage.

"However, the maintenance staffs truck needed energy to be built and fueled.
He needs energy and energy is used to produce his food."
But he'd need that even if he was working on something else. As I said, it's a societal energy cost, not an energy input.

Aiden, if you are comparing systems the overhead costs have to be counted.
If one system has higher costs then another then that affects the comparison.
I just cannot see how you can avoid it.
The greenies want to count rejuvenation of mining sites and the
hospital costs of those affected by coal dust from passing trains etc.

I agree that in any situation of cloud the output will not be zero.
If however you are designing a system you have to build in some
assumptions and you do have to assume very heavy overcast in winter
at higher latitudes. The system has to work under the most pessimistic
assumptions, but that is not what the authors assumed.
The ERoEI of coal seems to be around 25 to 30 from what I have found
so 2 is pretty dismal.

Bazz,

If you are comparing systems then the overhead costs do indeed have to be counted. But they should be counted as overhead costs. They certainly shouldn't be shouldn't be used to pretend the systems are less energy efficient than they are, under the delusion that viability depends on EROEI reaching some arbitrary value or that the option with the highest EROEI is always best.

In the 20th century the EROEI of solar panels was often below 1, hence they were only useful for niche applications like providing power to very remote areas. But the days when solar panels were an energy sink are long gone. As long as net energy is positive, viability depends on cost not EROEI. And a proper comparison wouldn't use a single cost figure, but would look at the cost structure, how it's affected by different variables and how well suited it is to meeting the market's requirements.

Yet some fools still maintain the ludicrous position that a fudged EROEI figure is a better basis for those decisions.

An EROEI of 2 is indeed pretty dismal. It means there's a high energy investment and/or a low energy return, so it's unlikely to be commercially viable. But these are just two of many factors, and solar may be attractive because of its anticorrelation with wind.

The EROEI of coal may well be around 25 or 30. But of course that doesn't include the energy in the fuel itself; including that would of course bring the figure below 1. Renewables have the great advantage of not needing fuel.

"Renewables have the great advantage of not needing fuel", Aidan.

Don't be so silly Aidan, of course they need heaps of fuel, much more per Kilowatt hour produced than any traditional fuels.

The real difference is much of their fuel has to be expended in making the things, long before any positive return is received. Many of them will never actually produce in their lifetime, the energy/fuel expended in their manufacture.

Traditional fuels on the other hand only have to be harvested & supplied when power is required. These fuel costs are not required up front, but only as the power they supply is needed.

Well, Hasbeen, if you want to be ultrapedantic, fuel is also needed to build the fossil fuelled power plants.

And there's a great irony here in that you tell me not to be silly when you yourself in the same sentence are being absolutely idiotic!

Including construction, the output from renewables is much higher than the input, whereas when generating electricity from fossil fuels, the output is never as high as the energy in the fuel.

Back in the 20th century, solar cells took more energy to manufacture than they the electricity they produced. But those days are long gone, and even at high latitudes the conclusion that solar's a net energy sink can only be arrived at by fudging the figures (as the study Bazz linked to did by assigning energy values to non energy inputs).

And though you claim wind power is a net energy sink, all the figures I've seen show a much higher EROEI (typically between 15 and 20, but varying according to location and size of turbine, with bigger ones giving higher values). Try looking at the facts instead of basing your opinion on you prejudices!

hasbeen: Traditional fuels on the other hand only have to be harvested & supplied when power is required. These fuel costs are not required up front, but only as the power they supply is needed

And there are no costs in fuel to manufacture an enormous coal fire power station, the rail to feed it with coal, the excavation of the mine, the machinery to run the mine,
The accommodation and transport for the mine workers, the accommodation and transport for the power station operators.
Come off the grass hasbeen, you are doing a bit of cherry picking as usual.