Posted By: Ed Daviespayback in 44 months over a 25 year life

Ed, I think you ought to rigorously add 'in Energy terms' in case people confuse what you're saying with the widespread concept of financial payback.

44 months payback seems pretty good in financial terms but is horribly low in EROEI terms - far far lower than the assumptions that Western society is built upon. The Romans, the Easter Islanders, and many more collapsing civilisations didn't see it coming either.

Posted By: HalcyonRichardFooled me for a bit as well. It states power then liters/day. So I would think that 250 kW for a day for 600 litres of fuel. i.e. 250 x 24 kWh/ 600 litres This gives 10 kWh/litre.

Yes, that was the bit.

Tom, if you take into account the amount of energy and time (generally solar, thousands of years) to create a kg of coal or oil, how does that affect your figures?

So you have put some bounds at the very start.

So taking the PV example, if you make a solar farm that take say 5 MWh to manufacure, and delivers 1 MWh a year, then with that 1 MWh a year you start making more solar farms, how do you calculate that EROEI?

Posted By: SteamyTeaSo taking the PV example, if you make a solar farm that take say 5 MWh to manufacure, and delivers 1 MWh a year, then with that 1 MWh a year you start making more solar farms, how do you calculate that EROEI?

That's EROEI = 1. All of the output from the first solar farm is 100% consumed by the energy-production industry - there's none left over for useful use by anyone or anything out side of that industry. That is exactly what's happening at the point of collapse of a civilisation.

Please re-design the proposition!

I figure that if some countries are concerned about energy independence in the future then they may well use this technology with nuclear power as the source of electricity rather than renewables.

Hmm, I don't think it has been clearly shown why an advanced civilisation needs a high EROEI or what the lower bound is other than 1, much less that 6.8 should be catastrophic. It is not even generally agreed why civilisations such as that of Easter Island fell - the resource depletion explanation is by no means universally accepted.

And payback time seems pretty meaningless taken out of context. If I planted a crop and it took 44 months to grow and be harvested and it paid back only the energy I put in, that would be terrible. If I was building a hydro-electric dam I think I'd be pretty pleased if it only took 44 months to pay back the energy invested and then had another hundred or two hundred years of life in it.

Ed

Hi Tom,
I agree that we need the improvements. But they are happening as we speak. What target do we need to hit. Offshore Wind is currently better than 20 and onshore is even better. PV is improving all the time this article talks about EROEI of 15 to 60. That's a fantastic improvement on the 1970's. And the improvements are still happening. I think the low EROEI in past declines was probably a result of the decline rather than the cause. Every body apart from the few know coal tar sands are a bad deal. And what about Germany ? Thay are heading for 100% renewables. Will that mean that all their EROEI's will be infinite ?

"However, today’s PVs return far more energy than that embodied in the life cycle of
a solar system (see Figure 1).Their energy payback times (EPBT)—the time it takes to produce
all the energy used in their life cycles—currently are between six months to two years, depending on the location/solar irradiation and the technology. And with expected life times of 30 years, their
ERRs are in the range of 60:1 to 15:1, depending on the location and the technology, thus returning 15 to 60 times more energy than the energy they use."

If you look at the chart of EROEI then we have been moving to the left of the chart with lower EROEI. But recentley it's been going the other way with renewables. PV is increasing EROEI all the time. The cheap oil times are nearly over the cheap renewable times are just getting started.

Richard

Posted By: HalcyonRichardwhat about Germany ? Thay are heading for 100% renewables. Will that mean that all their EROEI's will be infinite ?

The point is, Renewables are very far from 'infinite' EROEI - that's a confusion.

Posted By: HalcyonRichardThe cheap oil times are nearly over the cheap renewable times are just getting started.

Let's hope. Of course you know it's nothing to do with 'cheap' i.e. in money terms. The lowest of EROEI processes can be superb financial investment - in fact that's what's driving hideous tar sands etc.

EROEI (and don't forget, more broadly, RORI) is Economics without mention of money - for the first time, absence of higher-EROEI alternatives breaks the usual theory of substitution of one monetarised commodity with another one.

If the Renewable installation was there as a 'given' before calculations began, and if all the energy produced was available for useful use outside of the energy industry, without environmental or other continuing cost, then yes, infinite EROEI.

A good place to start from - because it ain't like that, and the calculated EROEI figure is the measure of how far the Renewable source, in a full accounting of all its intersections with the world, declines from that ideal, in reality.

It turns out that the installation produces energy, but that a fair bit of it is consumed by the energy industry, not just in distributing the energy produced, but in maintaining and eventually modernising or replacing the installation, in building more installations, in ameliorating the installation's impact on the environment - and those are only skimming the surface of the installation's fullest-accounting cost to the planet and to society. If we don't account for all those - and same for every other 'thing' that humans do, then we're fooling ourselves. But the planet isn't fooled, and sooner or later faces us with reality.

One of the 'costs' that the Renewable installation has to carry its share of, is the growing Security measures that arise from the kind of society that the sum-total of human activity creates. As EROEI falls, and the surplus that's left for useful use by the rest of us contracts even faster, 'essentials' like Security, Military etc will take first priority, leaving even faster contraction of what's left for 'us'.

Posted By: fostertomTherefore put in suitably large fudge factors.

to be absolutely sure there's no self-deception going on.

Posted By: fostertomAn IPHS (Intergovernmental Panel on Human Sustainability) should be able, over few decades, to get on top of that, to 95% certainty, if anyone was interested.

Audi opened a 6 MW power-to-gas facility more than a year ago not sure how well it is performing or how the costing has worked out but it was a major investment and we can only hope it works out and is replicated.
https://www.youtube.com/watch?v=6TX82PRxHvI

Posted By: bxmanbut not that much Gas Storage at the moment

The NIMBYs put paid to that years ago.

Lets hope all progresses rapidly , it seems that the Germans are certainly leading this technology.
As far as I can see Sunfire are not associated with the Audi project .

However what we need is a catalyst that will produce Propane rather than Methane.

LPG is an excellent road fuel.
I can recommend it to anyone having used it for 8 or so years.

Posted By: SteamyTea

Posted By: SeretAll data is incomplete. The question is whether it's accurate

The Laws of Thermodynamics seem pretty complete, accurate and precise.

I meant actual data. By definition data points only approximate reality, as they're a discrete approximation of a continuous phenomenon. This is what the Butterfly Effect is about, since a model can't simulate reality with full accuracy it'll eventually diverge.